Extent Of Microvascular Obstruction Research Articles

Association of stress hyperglycemia ratio with left ventricular function and microvascular obstruction in patients with ST-segment elevation myocardial infarction: a 3.0 T cardiac magnetic resonance study.

Stress hyperglycemia, which is associated with poor prognosis in patients with acute myocardial infarction (AMI), can be determined using the stress hyperglycemia ratio (SHR). Impaired left ventricular function and microvascular obstruction (MVO) diagnosed using cardiac magnetic resonance (CMR) have also been proven to be linked to poor prognosis in patients with AMI and aid in risk stratification. However, there have been no studies on the correlation between fasting SHR and left ventricular function and MVO in patients with acute ST-segment elevation myocardial infarction (ASTEMI). Therefore, this study aimed to investigate the additive effect of fasting SHR on left ventricular function and global deformation in patients with ASTEMI and to explore the association between fasting SHR and MVO. Consecutive patients who underwent CMR at index admission (3-7 days) after primary percutaneous coronary intervention (PPCI) were enrolled in this study. Basic clinical, biochemical, and CMR data were obtained and compared among all patients grouped by fasting SHR tertiles: SHR1: SHR < 0.85; SHR2: 0.85 ≤ SHR < 1.01; and SHR3: SHR ≥ 1.01. Spearman's rho (r) was used to assess the relationship between fasting SHR and left ventricular function, myocardial strain, and the extent of MVO. Multivariable linear regression analysis was performed to evaluate the determinants of left ventricular function and myocardial strain impairment in all patients with AMI. Univariable and multivariable regression analyses were performed to investigate the correlation between fasting SHR and the presence and extent of MVO in patients with AMI and those with AMI and diabetes mellitus (DM). A total of 357 patients with ASTEMI were enrolled in this study. Left ventricular ejection fraction (LVEF) and left ventricular global function index (LVGFI) were significantly lower in SHR2 and SHR3 than in SHR1. Compared with SHR1 and SHR2 groups, left ventricular strain was lower in SHR3, as evidenced by global radial (GRS), global circumferential (GCS), and global longitudinal (GLS) strains. Fasting SHR were negatively correlated with LVEF, LVGFI, and GRS (r = - 0.252; r = - 0.261; and r = - 0.245; all P<0.001) and positively correlated with GCS (r = 0.221) and GLS (r = 0.249; all P <0.001). Multivariable linear regression analysis showed that fasting SHR was an independent determinant of impaired LVEF, LVGFI, GRS, and GLS. Furthermore, multivariable regression analysis after adjusting for covariates signified that fasting SHR was associated with the presence and extent of MVO in patients with AMI and those with AMI and DM. Fasting SHR in patients with ASTEMI successfully treated using PPCI is independently associated with impaired cardiac function and MVO. In patients with AMI and DM, fasting SHR is an independent determinant of the presence and extent of MVO.

Effect of Cangrelor on Infarct Size in ST-Segment Elevation Myocardial Infarction Treated By Primary Percutaneous Coronary Intervention: A Randomized Controlled Trial (The PITRI Trial).

Background: The administration of intravenous cangrelor at reperfusion achieves faster onset of platelet P2Y12 inhibition than oral ticagrelor and has been shown to reduce myocardial infarct (MI) size in the pre-clinical setting. We hypothesized that the administration of cangrelor at reperfusion will reduce MI size and prevent microvascular obstruction (MVO) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Methods: This was a Phase 2, multi-center, randomized, double-blind, placebo controlled clinical trial conducted between November 2017 to November 2021 in six cardiac centers in Singapore (NCT03102723). Patients were randomized to receive either cangrelor or placeboinitiated prior to the PPCI procedure on top of oral ticagrelor. The key exclusion criteria included: presenting <6 hours of symptom onset, prior MI and stroke or transient ischemic attack; on concomitant oral anticoagulants; and a contraindication for cardiovascular magnetic resonance (CMR). The primary efficacy endpoint was acute MI size by CMR within the first week expressed as percentage of the left ventricle mass ( %LVmass). MVO was identified as areas of dark core of hypoenhancement within areas of late gadolinium enhancement. The primary safety endpoint was Bleeding Academic Research Consortium (BARC)-defined major bleeding in the first 48 hours. Continuous variables were compared by Mann-Whitney U test [reported as median (1st quartile- 3rd quartile)] and categorical variables were compared by Fisher's exact test. A 2-sided P<0.05 was considered statistically significant. Results: Of 209 recruited patients, 164 patients (78% ) completed the acute CMR scan. There were no significant differences in acute MI size [placebo: 14.9 (7.3 - 22.6) %LVmass versus cangrelor: 16.3 (9.9 - 24.4)%LVmass, P=0.40] or the incidence [placebo: 48% versus cangrelor: 47%, P=0.99] and extent of MVO [placebo:1.63 (0.60 - 4.65)%LVmass versus cangrelor: 1.18 (0.53 - 3.37)%LVmass, P=0.46] between placebo and cangrelor despite a two-fold decrease in platelet reactivity with cangrelor. There were no BARC-defined major bleeding events in either group in the first 48 hours. Conclusions: Cangrelor administered at time of PPCI did not reduce acute MI size or prevent MVO in STEMI patients given oral ticagrelor despite a significant reduction of platelet reactivity during the PCI procedure.

Microvascular Obstruction in Patients With Anterior STEMI Treated With Supersaturated Oxygen

BackgroundSupersaturated oxygen (SSO2) delivered into the left anterior descending coronary artery after percutaneous coronary intervention (PCI) for anterior ST-segment elevation myocardial infarction (STEMI) has been shown to reduce infarct size, but its effects on microvascular obstruction (MVO) are unknown. The aim of this study was to compare MVO in patients with anterior STEMI treated with SSO2 after successful primary PCI from 2 studies (the optimized SSO2 pilot and IC-HOT) with similar patients from 7 randomized trials who underwent primary PCI without SSO2 treatment. MethodsA total of 874 patients with anterior STEMI who underwent MVO assessment using cardiac magnetic resonance imaging within 10 days after primary PCI were included, of whom 90 patients (10.3%) were treated with SSO2. The primary end point was the extent of MVO as a continuous measure in a weighted multivariable model. The secondary end point was the presence of MVO. ResultsSSO2 therapy was independently associated with a lower extent of MVO compared with no SSO2 therapy (coefficient, −1.35; 95% CI, −2.58 to −0.11; P = .03). SSO2 therapy was also associated with a borderline lower risk of any MVO (adjusted odds ratio, 0.56; 95% CI, 0.31-1.00; P = .051). ConclusionsIn the present individual patient data pooled analysis from 9 studies, SSO2 therapy was associated with less MVO after successful primary PCI for anterior STEMI.

Growth differentiation factor-15 as a negative predictor for microvascular obstruction in ST-segment elevation myocardial infarction after primary percutaneous coronary intervention.

Growth differentiation factor-15 (GDF-15) is an anti-inflammatory cytokine with cardioprotective effects, but circulating GDF-15 concentration predicts adverse cardiovascular outcomes in clinical settings. Microvascular obstruction (MVO) formation contributed to poor prognosis in patients with ST-segment elevation myocardial infarction (STEMI) after primary percutaneous coronary intervention (pPCI). We aimed to investigate GDF-15 concentration in relation to cardiac magnetic resonance (CMR)-derived MVO in STEMI patients after pPCI, which might help better understand the role of GDF-15 in STEMI. GDF-15 levels at 6h after pPCI and MVO extent at day 5 ± 2 after pPCI were measured in 74 STEMI patients (mean age 60.3 ± 12.8years, 86.5% men). The adjusted association of GDF-15 with MVO was analyzed with MVO treated as a categorized variable (extensive MVO, defined as MVO extent ≥ 2.6% of left ventricular (LV)) and a continuous variable (MVO mass, % of LV), respectively, in multivariate logistic and linear regression models. 41.9% of the patients developed extensive MVO after pPCI. In multivariate analysis, the odds ratio (95% confidential interval (CI)) of each standard deviation (SD) increase in GDF-15 for developing extensive MVO was 0.46 (0.21, 0.82), p = 0.02). Consistently, when MVO was used a continuous variable, each SD increase in GDF-15 was associated with a substantially lower MVO mass (β - 0.42, standard error 0.19, p = 0.03). GDF-15 was a negative predictor for MVO in STEMI patients after pPCI. The observation was consistent with results from experiment studies, suggesting a potential protective effect of GDF-15 against cardiac injury.

Time of day dependent symptom onset is not associated with left ventricular function and myocardial damage after ST-segment elevation myocardial infarction

Abstract Background Circadian processes are suggested to influence ischemic injury in ST-segment elevation myocardial infarction (STEMI). Observational data suspect a circadian dependence of the occurrence of microvascular obstruction (MVO) in patients with STEMI. However, these observations derive from a small sample size and circadian variations in left ventricular function and myocardial damage after STEMI are still a matter of controversy. Purpose We aimed to investigate the association of time of day dependent symptom onset with left ventricular ejection fraction (LVEF), infarct size (IS) and MVO in a large cohort of STEMI patients treated with primary percutaneous coronary intervention (PCI). Methods This observational study investigated acute STEMI patients treated with primary PCI. Cardiac magnetic resonance (CMR) imaging was performed within 1 week after the index event for the determination of left ventricular function and infarct characteristics. The time of symptom onset was used to discriminate patients according to LVEF, IS as well as MVO occurrence and extent over a 24 hours cycle to evaluate circadian behavior. Results In final analysis, 889 acute STEMI patients treated with primary PCI with a delay of 189 [120-315] minutes were included. Median age of the overall cohort was 57 [51-66] years and 17% were female. Median LVEF was 49 [42-55]%, IS assumed 15.5 [8.0-24.7]% of left ventricular myocardial mass (LVMM) and MVO occurred in 57% of STEMI patients. No hourly differences between symptom onset and MVO occurrence (p=0.108), MVO extent (p=0.735), LVEF (p=0.644) and IS (p=0.722) have been evaluated. When comparing 3 hourly segments of symptom onset, no variations in MVO occurrence (p=0.114), MVO extent (p=0.308), LVEF (p=0.547) and IS (p=0.405) were observed. Conclusions No circadian variations in symptom onset and the occurrence and extent of MVO, LVEF and IS were observed in this large cohort of STEMI patients treated with primary PCI. Further research is needed to investigate the complex interplay between circadian processes and ischemic injury in this patient population.

A pilot randomized controlled trial of novel reperfusion method in patients of acute st elevation myocardial infarction during primary percutaneous coronary intervention

Abstract Objectives This study was conducted to explore the feasibility, clinical safety and potential effects of a novel reperfusion method, Volume-Controlled Reperfusion (VCR) in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Background Reperfusion injury is associated with larger infarct size (IS) and drawback of long-term overcome. Microvascular obstruction (MVO) as detected on late gadolinium-enhanced cardiovascular magnetic resonance (LGE-CMR) is the most used index for assessment of reperfusion injury. To date, there is no feasible gradual reperfusion method in primary PCI setting. VCR is an original reperfusion method feasible in primary PCI for both accurate gradual reperfusion and intermittent flow. Methods A total of 60 patients with STEMI presenting within 12 h of symptom onset undergoing PPCI were randomized enrolled, 30 patients in VCR group and 30 patients in control group with routine PCI only. VCR was performed with the dual catheter technique, 10ml of artery blood diluted with10ml of heparin saline infused via manual aspiration catheter at speed of 20ml/min for 10 rounds after suspending the antegrade flow using a prophylactic inflated balloon. Then, routine PCI procedure as usual. The primary endpoint was major adverse cardiac events (MACE) during hospitalization, the main second endpoint was the MVO extent difference measured on day 5-7 post-procedure. Results Baseline characteristics were well matched between two groups. No major adverse cardiac events (MACE) found in-hospital or 30 days followed up. There were no complications associated with VCR procedure. 43 patients had LGE-CMR exam (22 in Control group, 21 in VCR group, among them, 14/22 were anterior wall control and 14/21 VCR). There was no significant difference in infarct size, MVO or CMR-LVEF in total patients between VCR and control. However, significant difference in CMR-LVEF was noted between control and VCR anterior wall subgroup (40.53 ± 7.39 vs50.55 ± 7.55; P=0.002), the average of MVO and MVO of infarct size were smaller in VCR group while no significant difference. Conclusions This is the pilot RCT study showed VCR method was feasibility and clinical safe among patients with acute STEMI during PPCI and 30 days followed up, indicated potential attenuate effect in reperfusion injury as well. Staged II study is needed to verify clinical benefit.VCR illustrationLGE-CMR figure

Microvascular Obstruction in Acute Myocardial Infarction, a Potential Therapeutic Target.

Microvascular obstruction (MVO) is a recognised phenomenon following mechanical reperfusion in patients presenting with ST-segment elevation myocardial infarction (STEMI). Invasive and non-invasive modalities to detect and measure the extent of MVO vary in their accuracy, suggesting that this phenomenon may reflect a spectrum of pathophysiological changes at the level of coronary microcirculation. The importance of detecting MVO lies in the observation that its presence adds incremental risk to patients following STEMI treatment. This increased risk is associated with adverse cardiac remodelling seen on cardiac imaging, increased infarct size, and worse patient outcomes. This review provides an outline of the pathophysiology, clinical implications, and prognosis of MVO in STEMI. It describes historic and novel pharmacological and non-pharmacological therapies to address this phenomenon in conjunction with primary PCI.

Coronary No-Reflow after Primary Percutaneous Coronary Intervention-Current Knowledge on Pathophysiology, Diagnosis, Clinical Impact and Therapy.

Coronary no-reflow (CNR) is a frequent phenomenon that develops in patients with ST-segment elevation myocardial infarction (STEMI) following reperfusion therapy. CNR is highly dynamic, develops gradually (over hours) and persists for days to weeks after reperfusion. Microvascular obstruction (MVO) developing as a consequence of myocardial ischemia, distal embolization and reperfusion-related injury is the main pathophysiological mechanism of CNR. The frequency of CNR or MVO after primary PCI differs widely depending on the sensitivity of the tools used for diagnosis and timing of examination. Coronary angiography is readily available and most convenient to diagnose CNR but it is highly conservative and underestimates the true frequency of CNR. Cardiac magnetic resonance (CMR) imaging is the most sensitive method to diagnose MVO and CNR that provides information on the presence, localization and extent of MVO. CMR imaging detects intramyocardial hemorrhage and accurately estimates the infarct size. MVO and CNR markedly negate the benefits of reperfusion therapy and contribute to poor clinical outcomes including adverse remodeling of left ventricle, worsening or new congestive heart failure and reduced survival. Despite extensive research and the use of therapies that target almost all known pathophysiological mechanisms of CNR, no therapy has been found that prevents or reverses CNR and provides consistent clinical benefit in patients with STEMI undergoing reperfusion. Currently, the prevention or alleviation of MVO and CNR remain unmet goals in the therapy of STEMI that continue to be under intense research.

Impact of Persistent Microvascular Obstruction Late After STEMI on Adverse LV Remodeling: A CMR Study

BackgroundLittle is known about the occurrence and implications of persistent microvascular obstruction (MVO) after reperfused ST-segment elevation myocardial infarction (STEMI). ObjectivesThe authors used cardiac magnetic resonance (CMR) to characterize the impact of persistent MVO on adverse left ventricular remodeling (ALVR). MethodsA prospective registry of 471 STEMI patients underwent CMR 7 (IQR: 5-10) days and 198 (IQR: 167-231) days after infarction. MVO (≥1 segment) and ALVR (relative increase >15% at follow-up CMR) of left ventricular end-diastolic index (LVEDVI) and left ventricular end-systolic volume index (LVESVI) were determined. ResultsOne-week MVO occurred in 209 patients (44%) and persisted in 30 (6%). The extent of MVO (P = 0.026) and intramyocardial hemorrhage (P = 0.001) at 1 week were independently associated with the magnitude of MVO at follow-up CMR. Compared with patients without MVO (n = 262, 56%) or with MVO only at 1 week (n = 179, 38%), those with persistent MVO at follow-up (n = 30, 6%) showed higher rates of ALVR-LVEDVI (22%, 27%, and 50%; P = 0.003) and ALVR-LVESVI (20%, 21%, and 53%; P < 0.001). After adjustment, persistent MVO at follow-up (≥1 segment) was independently associated with ΔLVEDVI (relative increase, %) (P < 0.001) and ΔLVESVI (P < 0.001). Compared with a 1:1 propensity score–matched population on CMR variables made up of 30 patients with MVO only at 1 week, patients with persistent MVO more frequently displayed ALVR-LVEDVI (12% vs 50%; P = 0.003) and ALVR-LVESVI (12% vs 53%; P = 0.001). ConclusionsMVO persists in a small percentage of patients in chronic phase after STEMI and exerts deleterious effects in terms of LV remodeling. These findings fuel the need for further research on microvascular injury repair.

Pre-stenting residual thrombotic volume assessed by dual quantitative coronary angiography predicts microvascular obstruction in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Microvascular obstruction (MVO) is a frequent occurrence after primary percutaneous coronary intervention (pPCI), and is associated with adverse left ventricular remodeling and worse clinical outcome. Distal embolization of thrombotic material is one of the most important underlying mechanisms. The aim of this study was to investigate the relation between the thrombotic volume evaluated by dual quantitative coronary angiography (QCA) prior to stenting and the occurrence of MVO as assessed by cardiac magnetic resonance (CMR). Forty-eight patients with ST-segment elevation myocardial infarction (STEMI) undergoing pPCI and receiving CMR within 7 days from admission were included. Pre-stenting residual thrombus volume at the site of the culprit lesion was measured by applying automated edge detection and video-assisted densitometry techniques (i.e., dual-QCA), and patients were categorized into tertiles of thrombus volume. The presence of delayed-enhancement MVO, as well as its extent (MVO mass), were assessed by CMR. Pre-stenting dual-QCA thrombus volume was significantly greater in patients with MVO than in those without (5.85 mm3 [2.05-16.71] vs. 1.88 mm3 [1.03-6.92], P=0.009). Patients in the highest tertile showed greater MVO mass compared to those in the mid and lowest tertiles (113.3 gr [0.0-203.8] vs. 58.5 g [0.00-144.4] vs. 0.0 g [0.0-60.225], respectively; P=0.031). The best cut-off value of dual-QCA thrombus volume for prediction of MVO was 2.07 mm3 (AUC: 0.720). The addition of dual-QCA thrombus volume to the traditional angiographic indices of no-reflow enhanced the prediction of MVO by CMR (R=0.752). Pre-stenting dual-QCA thrombus volume is associated with the presence and extent of MVO detected by CMR in patients with STEMI. This methodology may aid the identification of patients at higher risk of MVO and guide adoption of preventive strategies.

Impact of persistent MVO late after STEMI on adverse left ventricular remodelling: a CMR study

Abstract Background Despite successful revascularization at the epicardial level, microvascular obstruction (MVO) appears soon after reperfusion in up to 50% of cases. Early MVO has been solidly associated with adverse resulting cardiac structure and heightened risk of future cardiovascular events. Although clinical and experimental studies demostrated the spontaneous repair of MVO, little is known about the occurrence and implications of persistent MVO late after infarction. Purpose We used cardiovascular magnetic resonance (CMR) to characterize the impact of persistent MVO late after reperfused ST-segment elevation myocardial infarction (STEMI) on adverse left ventricular (LV) remodelling (ALVR). Methods A prospective registry of 471 STEMI patients underwent CMR 7 [5–10] and 198 [167–231] days post infarction, and MVO (&amp;gt;1 segment) and ALVR (relative increase &amp;gt;15% at follow-up CMR) of LV end-diastolic (LVEDVI) and end-systolic volume indices (LVESVI) were determined. Results One-week MVO occurred in 209 patients (44%) and persisted in 30 of these (6%). Most patients with persistent MVO (22/30, 73%) displayed extensive (&amp;gt;2.5% of LV mass) MVO at 1 week. Compared with patients without MVO (n=262, 56%) or with MVO only at 1 week (n=179, 38%), those with persistent MVO at follow-up (n=30, 6%) showed higher rates of ALVR-LVEDVI (22%, 27%, 50% p=0.003) and ALVR-LVESVI (20%, 21%, 53% p&amp;lt;0.001). After adjustment, the extent (% of LV mass) of MVO at follow-up was independently associated with ΔLVEDVI (relative increase, %) (p=0.01) and ΔLVESVI (p=0.03). Compared to a 1:1 matched population of 30 patients with MVO only at 1 week, patients with persistent MVO more frequently displayed ALVR-LVEDVI (12% vs. 50%, p=0.003) and ALVR-LVESVI (12% vs. 53%, p=0.001). Conclusion MVO persists in a small percentage of patients in chronic phase after STEMI and exerts deleterious effects in terms of LV remodelling. These findings fuel the need for further research on microvascular injury repair. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by “Instituto de Salud Carlos III” and “Fondos Europeos de Desarrollo Regional FEDER” [grant numbers PI20/00637, PI15/00531, FI18/00320, and CIBERCV16/11/00486] and by Conselleria de Educaciόn – Generalitat Valenciana (PROMETEO/2021/008).

Índice de resistencia microcirculatoria y obstrucción microvascular en la resonancia magnética cardiaca tras un IAMCEST

Introduction and objectivesThe index of microcirculatory resistance (IMR) measured after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is associated with microvascular obstruction (MVO) and adverse clinical events. To evaluate MVO after successful primary PCI for STEMI without pressure wires or hyperemic agents, we investigated the feasibility and usefulness of functional angiography-derived IMR (angio-IMR). MethodsThe current study included a total of 285 STEMI patients who underwent primary PCI and cardiac magnetic resonance (CMR). Angio-IMR of the culprit vessel after successful primary PCI was calculated using commercial software. MVO, infarct size, and myocardial salvage index were assessed using CMR, which was obtained a median of 3.0 days [interquartile range, 3.0-5.0] after primary PCI. ResultsAmong the total population, 154 patients (54.0%) showed elevated angio-IMR (> 40 U) in the culprit vessel. MVO was significantly more prevalent in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (88.3% vs 32.1%, P <.001). Infarct size, extent of MVO, and area at risk were significantly larger in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (P <.001 for all). Angio-IMR showed a significantly higher discriminatory ability for the presence of MVO than thrombolysis in myocardial infarction flow grade or myocardial blush grade (area under the curve: 0.821, 0.504, and 0.496, respectively, P <.001). ConclusionsAngio-IMR was significantly associated with CMR-derived infarct size, extent of MVO, and area at risk. An elevated angio-IMR (> 40 U) after primary PCI for STEMI was highly predictive of the presence of MVO in CMR.This trial was registered at ClnicalTrialsgov (Identifier: NCT04828681).

Functional angiography-derived index of microcirculatory resistance validated with microvascular obstruction in cardiac magnetic resonance after STEMI

Introduction and objectivesThe index of microcirculatory resistance (IMR) measured after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is associated with microvascular obstruction (MVO) and adverse clinical events. To evaluate MVO after successful primary PCI for STEMI without pressure wires or hyperemic agents, we investigated the feasibility and usefulness of functional angiography-derived IMR (angio-IMR). MethodsThe current study included a total of 285 STEMI patients who underwent primary PCI and cardiac magnetic resonance (CMR). Angio-IMR of the culprit vessel after successful primary PCI was calculated using commercial software. MVO, infarct size, and myocardial salvage index were assessed using CMR, which was obtained a median of 3.0 days [interquartile range, 3.0-5.0] after primary PCI. ResultsAmong the total population, 154 patients (54.0%) showed elevated angio-IMR (> 40 U) in the culprit vessel. MVO was significantly more prevalent in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (88.3% vs 32.1%, P <.001). Infarct size, extent of MVO, and area at risk were significantly larger in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (P <.001 for all). Angio-IMR showed a significantly higher discriminatory ability for the presence of MVO than thrombolysis in myocardial infarction flow grade or myocardial blush grade (area under the curve: 0.821, 0.504, and 0.496, respectively, P <.001). ConclusionsAngio-IMR was significantly associated with CMR-derived infarct size, extent of MVO, and area at risk. An elevated angio-IMR (> 40 U) after primary PCI for STEMI was highly predictive of the presence of MVO in CMR.This trial was registered at ClnicalTrialsgov (Identifier: NCT04828681).

Post-ST-Segment-Elevation Myocardial Infarction Platelet Reactivity Is Associated With the Extent of Microvascular Obstruction and Infarct Size as Determined by Cardiac Magnetic Resonance Imaging.

BackgroundDespite optimized medical management and techniques of primary percutaneous coronary intervention, a substantial proportion of patients with ST‐segment–elevation myocardial infarction (STEMI) display significant microvascular damage. Thrombotic microvascular obstruction (MVO) has been implicated in the pathogenesis of microvascular and subsequent myocardial damage attributed to distal embolization and microvascular platelet plugging. However, there are only scarce data regarding the effect of platelet reactivity on MVO.Methods and ResultsWe prospectively evaluated 105 patients in 2 distinct periods (2012–2013 and 2016–2018) who presented with first ST‐segment–elevation myocardial infarction and underwent primary percutaneous coronary intervention. All patients were treated with dual antiplatelet therapy (DAPT). Blood samples were analyzed for platelet reactivity, and cardiac magnetic resonance imaging scans were evaluated for late gadolinium enhancement and MVO. DAPT suboptimal response was defined as hyporesponsiveness to either aspirin or P2Y12 receptor inhibitor agents and demonstrated in 31 patients (29.5%) of the current cohort. Suboptimal platelet response to DAPT was associated with a significantly greater extent of MVO when expressed as a percentage of the left ventricular mass, left ventricular scar, and the number of myocardial left ventricular segments showing MVO (P<0.01 for each). Adjusted multivariable logistic regression model revealed that suboptimal response to DAPT is significantly associated with both greater late gadolinium enhancement (P<0.01) and MVO extent (odds ratio, 3.7 [95% CI, 1.3–10.5]; P=0.01). Patients with a greater extent of MVO were more likely to sustain major adverse cardiovascular events at a 1‐year follow‐up (37% versus 11%; P<0.01).ConclusionsIn patients undergoing primary percutaneous coronary intervention for ST‐segment–elevation myocardial infarction, platelet reactivity in response to DAPT is a key predictor of the extent of both myocardial and microvascular damage.

Evolution of myocardial tissue injury over a decade after ST-elevation myocardial infarction: a cardiac magnetic resonance study

Abstract Background In patients with first ST-elevation myocardial infarction (STEMI), the evolution of myocardial tissue injury parameters over a decade as assessed by cardiac magnetic resonance (CMR) has not yet been described. Purpose This study examined long-term myocardial tissue injury dynamics in STEMI patients treated with primary percutaneous coronary intervention (PCI), as well as its association with patient characteristics. Methods A total of 104 patients with STEMI were included in this observational study. Sequential late gadolinium enhanced CMR studies (after 3 days [interquartile ranges (IQR) 2–4], 4 months [IQR 4–5] and 9 years [IQR 8–10]) were conducted to assess left ventricular (LV) dimensions and function, infarct size and microvascular obstruction (MVO). T2* mapping was added at 9 year scan to assess the presence of persistent iron within the infarct core. Results Infarct size decreased progressively from 13% of LV myocardial mass [IQR 7–21] to 10.2% [IQR 5.2–16.1] to 8% [IQR 2.4–12.3] (p&amp;lt;0.001), with an average reduction rate of 6.4% ± 3.4 per year. Relative reduction of infarct size from baseline to 9y follow-up was 43% [IQR 18–66], 21% [IQR 3–42] during the first 4m and 33% [IQR 8–54] between 4m and 9y after STEMI. Decrease of infarct size was associated with greater baseline infarct size (p&amp;lt;0.004) and extent of MVO (p=0.01). MVO was present in 60% (60/104) of patients at baseline, but in none of the follow-up examinations. Sixteen patients had persistent iron within the infarct core at 9 year CMR. Clinical and imaging associates of persistent iron included younger age at study inclusion (p=0.036), higher peak hs troponin T (p&amp;lt;0.001), higher peak creatine kinase (p&amp;lt;0.001) and higher peak CRP (p=0.036) as well as greater infarct size at any occasion (all p&amp;lt;0.001) and greater MVO (p&amp;lt;0.001). Patients with persistent iron showed less relative infarct size regression (51% [IQR 41–79] versus 46% [IQR 32–54], p=0.009). Conclusion In patients with STEMI, the evolution of infarct size is a dynamic process that extends well beyond the first few months after the acute event. MVO vanishes in the first few weeks after the index event in all patients. However, persistence of iron within the infarct core occurs up to a decade after reperfused STEMI, reflecting its irreversibility and is associated with the initial infarct severity and worse infarct healing. Funding Acknowledgement Type of funding sources: None. Central Illustration.Evolution of STEMI over a decade.

Cardio-pulmonary transit-time by cardiac magnetic resonance imaging: associates to infarct severity and adverse events after reperfused STEMI

Abstract Background Cardiac magnetic resonance (CMR) data on cardiopulmonary-transit-time (cpTT) and its associates with infarct characteristics and clinical outcome after reperfused ST-elevation myocardial infarction (STEMI) are lacking so far. Purpose cpTT may serve as surrogate parameter for integrative cardiac performance and has been linked to heart failure. Methods A total of 207 patients (179 men [87%], median age 55 [interquartile range (IQR) 49–64] with acute STEMI underwent CMR on day 3 [IQR 2–4] and 4 months (m) [IQR 4–5] after primary percutaneous coronary intervention. cpTT was taken as the time between the peaks of time-intensity curves of gadolinium contrast to pass from the right ventricle (RV) to the left ventricle (LV). Infarct size, extent of microvascular obstruction (MVO), RV and LV dimensions and function were assessed at both occasions. Results cpTT decreased significantly between baseline and 4m CMR scan (8.6 seconds [IQR 7.5–9.6] to 7.8 sec [IQR 7–8.7], respectively, p&amp;lt;0.0001). Patients with presence of MVO had significantly prolonged cpTT at baseline and 4m follow-up (all p&amp;lt;0.022). According to Cox regression analysis (“functional model”) baseline cpTT (hazard ratio (HR) 1.5, 95% confidence interval (CI) 1.1–2.2; p=0.008) remained significantly associated to the occurrence of major adverse cardiac events (MACE) after adjustment for LV ejection fraction (EF) and cardiac index. According to Cox regression analysis (“tissue model”) baseline cpTT (HR 1.462, 95% CI 1.02–2.09, p=0.039) as well as extent of MVO (HR 1.196, 95% CI 1.081–1.324, p=0.001) remained significantly associated to MACE after adjustment for infarct size. Baseline cpTT (area under the curve [AUC]: 0.725, 95% confidence interval [CI] 0.57–0.88; p&amp;lt;0.009) was significantly higher for the prediction of MACE compared to LV ejection fraction (AUC: 0.686, 95% CI 0.51–0.87; p=0.031. AUC difference: 0.039, p&amp;lt;0.03). In Kaplan-Meier analysis, cpTT ≥9 sec was associated with clinical adverse cardiovascular events (p=0.008). Conclusion Following reperfused STEMI, cpTT predicts prognosis independently of infarct size and systolic function. Moreover, cpTT provides significantly higher prognostic implication in comparison with LV ejection fraction. Funding Acknowledgement Type of funding sources: None. cpTT over the cardiac cycle.Computation of cpTT in 2 STEMI patients.

Impact of blood pressure on the extent of microvascular damage in the setting of reperfusion injury in STEMI asessed with magnetic resonance imaging

Abstract Hypertension is a poor prognostic factor following STEMI, however the impact of blood pressure (BP) on the extent of microvascular damage in the setting of acute ischemia -reperfusion injury has not yet been fully evaluated and this evaluation is the purpose of the present study. Methods A cohort of patients with acute STEMI referred to primary percutaneus intervention were prospectively included. Angiographic analysis were performed according to standard clinical practice and decision regarding type of stent and antiplatelet drugs was left to the discretion of cardiologist. Information about high blood pressure needing drug therapy before acute event and also BP levels at catheterization laboratory during reperfusion procedures were assessed. All patients underwent cardiac MRI during the first week post reperfusion with a standardized protocol including 8–10 short axis slices in order to asses: area of myocardium at risk (AR) as an area of signal hyperintensity &amp;gt;2sd with respect to the remote one in TSE-T2 sequences, necrosis size (NS) as signal hyperintensity &amp;gt;5 SDs relative to the remote in IR-FGE sequences, microvascular obstruction (MVO) as signal hypointensity in the infarct core in IR-FGE sequences and intra-infarct haemorrhage (IIH) as an area with T2*&amp;lt;20msec in T2* mapping sequences. The extent was quantified using a semi-automatic approach and expressed as a percentage of left ventricular mass. Results 94 patients,mean age 62,SD 13, 67% males were included. Hypertensive patients were more likely to have diabetes mellitus 43 vs 28% (p&amp;lt;0.05) while smoking was more frequent in non-hypertensive patients 41% vs 80%. (p&amp;lt;0.05). No differencies were found in extent of AR o rmyocardial salvage between groups, nevertheless hypertensive patients had significantly lower extent of NS, MVO and IIH. Regarding microvascular damage, hypertension showed a protective effect and presence of IIH was observed in 35% of hypertensive patients vs. 65% of non-hypertensive patients (p=0.019 OR: 0.9, p=0.04, CI: 0.1–0.9) and MVO in 40% vs 70% (OR: 0.2, p=0.02, CI: 0.1–0.6). Furthermore patients with BP levels below 120mmhg at cathetherization laboratory showed higher percentage of MVO (62% vs 36%, p&amp;lt;0.05) and IIH (36 vs 15%, p&amp;gt;0.05). Conclusions 1. Hypertension is associated with lower extent of necrosis and microvascular damage without differences in myocardial salvage and area of myocardium at risk. 2. Low BP levels at catheterization laboratory were associated with a significantly higher extent of microvascular damage, so maintaining systolic blood pressure over 120mmhg during reperfusion procedures should be advised. Funding Acknowledgement Type of funding sources: None. Typical CMR sequences: T2w, T2*, IR-FGRCMR segmental analysis with T2* mapping

Evaluation of myocardial reperfusion in patients undergoing cangrelor supported primary PCI for STEMI

Abstract Background Optimal myocardial reperfusion is the main goal of pharmaco-invasive treatment in STEMI patients. Cangrelor is a new intravenous P2Y12 inhibitor, mainly used in intra-procedural PCI setting of STEMI patients. Intracoronary cangrelor bolus application results in high local drug concentrations and may be more effective than a standard intravenous bolus. Aim This study aims to investigate the potential benefits of intracoronary versus intravenous cangrelor bolus in STEMI patients undergoing to primary PCI (p-PCI). Materials and methods Overall, 71 consecutive STEMI patients undergoing p-PCI were treated with intracoronary (n=37) or intravenous (n=34) bolus cangrelor administration with subsequent 2-hour intravenous infusion. The primary end point was ST-elevation reduction (STR) ≥50% at 30 minutes and at 24 hours after p-PCI. Secondary end points were STR ≥70% at 30 min after p-PC, TIMI frame count, and the QT dispersion (QTd). Moreover, stent thrombosis, bleeding events according to BARC classification, and 30-day mortality have been evaluated as safety explorative end points. Results STEMI patients treated with intravenous Cangrelor bolus had a higher rate of STR ≥50% either at 30 minutes (72% vs. 45%; p=0.033) or at 24 hours after p-PCI (87.1% vs. 63.6%; p=0.030) as compared to patients treated with intracoronary Cangrelor bolus; similarly, STR ≥70% at 30 minutes was more frequent in the intravenous bolus group as compared to intracoronary one (67% vs. 29% p=0.02). Furthermore, multivariable analysis demonstrated that intravenous Cangrelor bolus administration was an independent predictor of STR ≥50% (OR 3.586; 95% CI 1.134 to 11.335; p=0.030). No differences according to the TIMI frame count and the QTd were found. No stent thrombosis were observed at 30 days. The incidence of mortality and bleeding events (BARC 3–5) were comparable among study groups (30 days-death: 2.9% vs 5.4%, p=0.606; BARC 3–5 bleedings: 17.6% vs 13.5% p=0.630). Conclusion Intravenous coronary bolus administration of cangrelor in primary PCI is superior to intracoronary treatment with respect to extent of microvascular obstruction, and perfusion. Funding Acknowledgement Type of funding sources: None.

Impact of COVID-19 pandemic restrictions on ST-elevation myocardial infarction: a cardiac magnetic resonance imaging study.

AimsThe severity of myocardial tissue damage following ST-elevation myocardial infarction (STEMI) strongly determines short- and long-term prognosis. This study explored the impact of the coronavirus disease 2019 (COVID-19) pandemic and associated public health restrictions on infarct severity.Methods and resultsSTEMI patients treated with primary percutaneous coronary intervention (PCI) and included in the prospective Magnetic Resonance Imaging in Acute ST-Elevation Myocardial Infarction (MARINA-STEMI) cohort study from 2015- 2020 (n = 474) were categorized according to (i) timeframes with and without major public health restrictions in 2020, and (ii) timeframes of major public health restrictions during 2020 and during the corresponding timeframes between 2015-2019. Myocardial damage was evaluated by cardiac magnetic resonance imaging. During major public health restrictions in 2020 (n = 48), there was an increase in infarct size (22 [IQR 12-29] vs. 14 [IQR 6-23]%, P < 0.01), a higher frequency (77% vs. 52%, P < 0.01) and larger extent of microvascular obstruction (1.5 [IQR 0.1-11.4] vs. 0.2 [IQR 0.0-2.6]%, P < 0.01) and a higher rate of intramyocardial haemorrhage (56% vs. 34%, P = 0.02) as compared to the phases without major restrictions in 2020 (n = 101). These findings were confirmed in adjusted analysis and were consistent when comparing patients admitted in 2020 versus patients admitted in the “pre-pandemic” era (2015-2019). Patient characteristics were comparable between groups, except for a significantly longer total ischemia time (P < 0.01) and higher frequency of pre-PCI Thrombolysis in Myocardial Infarction (TIMI) flow 0 during times of major restrictions (P = 0.03).ConclusionThis study provides novel mechanistic insights demonstrating a significant increase in myocardial damage in STEMI patients admitted during the COVID-19 pandemic with a temporal relation to major public health restrictions.

Cardiac MRI to Visualize Myocardial Damage after ST-Segment Elevation Myocardial Infarction: A Review of Its Histologic Validation.

Cardiac MRI is a noninvasive diagnostic tool using nonionizing radiation that is widely used in patients with ST-segment elevation myocardial infarction (STEMI). Cardiac MRI depicts different prognosticating components of myocardial damage such as edema, intramyocardial hemorrhage (IMH), microvascular obstruction (MVO), and fibrosis. But how do cardiac MRI findings correlate to histologic findings? Shortly after STEMI, T2-weighted imaging and T2* mapping cardiac MRI depict, respectively, edema and IMH. The acute infarct size can be determined with late gadolinium enhancement (LGE) cardiac MRI. T2-weighted MRI should not be used for area-at-risk delineation because T2 values change dynamically over the first few days after STEMI and the severity of T2 abnormalities can be modulated with treatment. Furthermore, LGE cardiac MRI is the most accurate method to visualize MVO, which is characterized by hemorrhage, microvascular injury, and necrosis in histologic samples. In the chronic setting post-STEMI, LGE cardiac MRI is best used to detect replacement fibrosis (ie, final infarct size after injury healing). Finally, native T1 mapping has recently emerged as a contrast material-free method to measure infarct size that, however, remains inferior to LGE cardiac MRI. Especially LGE cardiac MRI-defined infarct size and the presence and extent of MVO may be used to monitor the effect of new therapeutic interventions in the treatment of reperfusion injury and infarct size reduction. © RSNA, 2021 Online supplemental material is available for this article.