Mitral Regurgitation Fraction Research Articles

Association of Secondary Mitral Regurgitation and Right Ventricular Dysfunction among Patients with Non-Ischemic Cardiomyopathy.

The association between secondary mitral regurgitation (MR) and right ventricular (RV) dysfunction in heart failure patients with non-ischemic cardiomyopathy (NICM) is unclear. Hence, our objective was to study the association between secondary MR and the occurrence of RV dysfunction among patients with NICM using cardiac magnetic resonance (CMR). Patients with NICM were enrolled in a prospective observational registry between 2008-2019. CMR was used to quantify MR severity along with RV function. RV dysfunction was defined as RV ejection fraction <45%. The outcome of the study was a composite event of all-cause death, heart transplantation, or left ventricular assist device implantation at follow-up. In the study cohort of 241 patients, RV dysfunction (RVEF < 45%) was present in 148 (61%). In comparison to patients without RV dysfunction, those with RV dysfunction had higher median MR volume (23 ml [IQR 16-31ml] vs 18 ml [IQR 12-25 ml], P=0.002) and MR fraction (33% [IQR 25-43%] vs 22% [IQR 15-29%], P<0.001). Furthermore, secondary MR was independently associated with RV dysfunction: MR volume ≥ 24ml (OR 3.21, 95% CI 1.26-8.15, P= 0.01) and MR fraction≥ 30% (OR 5.46, 95% 2.23-13.35, P=0.002). Increasing RVEF (every 1% increase) was independently associated with lower risk of adverse events (HR 0.98, 95% 0.95, 1.00, P=0.047). In patients with NICM, the severity of secondary MR is associated with an increased prevalence of RV dysfunction. RV dysfunction is not only associated with the severity of LV dysfunction, but also with the severity of secondary MR.

Renal function improvement correlates with 3D echocardiographic findings: Effect of surgical mitral valve repair.

The association between surgical treatment of mitral regurgitation (MR) and renal function is not sufficiently well-known. We tried to evaluate renal function before and after the procedure of surgical mitral valve repair (SMVR) in degenerative severe MR. Patients with primary severe (4+) MR and normal left ventricular ejection fraction (LVEF) that underwent SMVR, examined by a cutting-edge 3-dimensional (3D) echocardiographic probe were enrolled in this study. We took three CKD-EPI equations to measure estimated glomerular filtration rate (eGFR) before SMVR and shortly before patients discharge. A total of 40 patients with baseline lower mean eGFR were evaluated. Measurements substantiated statistically significant improvements in eGFR (p < 0.001), multivariable linear regression modeling indicating prominent associations between increase in eGFR and decrease of MR (p = 0.003), decline of pulmonary arterial systolic pressure (p = 0.018), as well as increment of forward stroke volume (p = 0.02), in spite of LVEF reduction, left ventricular global longitudinal strain worsening and left atrial ejection fraction impairment. Renal function improves after SMVR in patients with degenerative significant MR and preserved LVEF, regardless of cardiac functional worsening.

Novel contouring method for optimizing MRI flow quantification in patients with aortic valve disease.

Optimizing MRI aortic flow quantification is crucial for accurate assessment of valvular disease severity. In this study, we sought to evaluate the accuracy of a novel method of contouring systolic aortic forward flow in comparison to standard contouring methods at various aortic levels. The study included a cohort of patients with native aortic valve (AoV) disease and a small control group referred to cardiac MRI over a 1-year period. Inclusion criteria included aortic flow quantification at aortic valve and one additional level, and no or trace mitral regurgitation (MR) documented both by the MRI AND an echocardiogram done within a year. In addition to flow quantification with standard contouring (SC), a novel Selective Systolic Contouring (SSC) method was performed at aortic valve level, contouring the area demarcated by the AoV leaflets in systole. The bias in each technique's estimate of aortic forward flow was calculated as the mean difference between aortic forward flow and left ventricular stroke volume (LV SV). 98 patients (mean age 56, 71% male) were included: 33 with tricuspid and 65 with congenitally abnormal (bicuspid or unicuspid) AoV. All methods tended to underestimate aortic forward flow, but the bias was smallest with the SSC method (p < 0.001). Therefore, SSC yielded the lowest estimates of mitral regurgitant volume (4.8 ml) and regurgitant fraction (3.9%) (p < 0.05). SSC at AoV level better approximates LV SV in our cohort, and may provide more accurate quantitative assessment of both aortic and mitral valve function.

Prognostic Power of Quantitative Assessment of Functional Mitral Regurgitation and Myocardial Scar Quantification by Cardiac Magnetic Resonance.

The severity classification of functional mitral regurgitation (FMR) remains controversial despite adverse prognosis and rapidly evolving interventions. Furthermore, it is unclear if quantitative assessment with cardiac magnetic resonance can provide incremental risk stratification for patients with ischemic cardiomyopathy (ICM) or non-ICM (NICM) in terms of FMR and late gadolinium enhancement (LGE). We evaluated the impact of quantitative cardiac magnetic resonance parameters on event-free survival separately for ICM and NICM, to assess prognostic FMR thresholds and interactions with LGE quantification. Patients (n=1414) undergoing cardiac magnetic resonance for cardiomyopathy (ejection fraction<50%) assessment from April 1, 2001 to December 31, 2017 were evaluated. The primary end point was all-cause death, heart transplant, or left ventricular assist device implantation during follow-up. Multivariable Cox analyses were conducted to determine the impact of FMR, LGE, and their interactions with event-free survival. There were 510 primary end points, 395/782 (50.5%) in ICM and 114/632 (18.0%) in NICM. Mitral regurgitation-fraction per 5% increase was independently associated with the primary end point, hazards ratios (95% CIs) of 1.04 (1.01-1.07; P=0.034) in ICM and 1.09 (1.02-1.16; P=0.011) in NICM. Optimal mitral regurgitation-fraction threshold for moderate and severe FMR were ≥20% and ≥35%, respectively, in both ICM and NICM, based on the prediction of the primary outcome. Similarly, optimal LGE thresholds were ≥5% in ICM and ≥2% in NICM. Mitral regurgitation-fraction×LGE emerged as a significant interaction for the primary end point in ICM (P=0.006), but not in NICM (P=0.971). Mitral regurgitation-fraction and LGE are key quantitative cardiac magnetic resonance biomarkers with differential associations with adverse outcomes in ICM and NICM. Optimal prognostic thresholds may provide important clinical risk prognostication and may further facilitate the ability to derive selection criteria to guide therapeutic decision-making.

Total regurgitant fraction to predict aortic valve surgery in patients with concomitant aortic and mitral regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Both aortic regurgitation (AR) and mitral regurgitation (MR) produce left ventricular (LV) volume overload (1). Current prognostic assessment of AR does not include the presence and magnitude of MR. Therefore, in patients with concomitant AR and MR we might be underestimating the future need of valve replacement surgery. Cardiac magnetic resonance (CMR) is a very precise tool to quantify LV volumes together with aortic and mitral regurgitant volumes. Combining data from cine and phase contrast sequences it is possible to obtain a set parameter: total regurgitant fraction (TRF). Purpose To describe the prognostic value of TRF in patients with concomitant AR and MR. Methods Patients with concomitant AR and MR with CMR studies were retrospectively recruited in three tertiary hospitals. Cases of at least moderate AR and any grade of MR were included in the analysis. Patients with indication of aortic valve surgery (symptoms, severe LV dilatation or reduced LV eyection fraction) in the moment of the CMR were excluded. Aortic regurgitant fraction (ARF) was calculated from the phase constrast data as the ratio of AR volume and LV forward volume. Mitral regurgitant Fraction (MRF) was calculated from the cine sequences as the ratio of the MR volume and the LV stroke volume (LVSV) . TRF was calculated as the ratio of mitral plus aortic regurgitant volumes and the LVSV (MRV+ARV/LVSV) Results 35 cases were analyzed, with a mean follow up period of 40 months. 9 patients developed indications of aortic valve surgery. TRF had an area under curve (AUC) to predict aortic valve surgery of 0.82, in opposite to aortic regurgitant fraction (ARF) which had an AUC of 0.75 (Figure 1) The optimum cutoff value of TRF and ARF to predict the need of surgery in our series were 38% and 27%, respectively. After 3 years of follow up 53% of patients with TRF &amp;gt; 38% had to be intervened (Figure 2A). In contrast, 32% of patients with ARF &amp;gt;27% had to be intervened (Figure 2B) Conclusion MR presence increases volume overload in patients with moderate or severe AR. TRF is a promising parameter to predict the need of aortic valve surgery in this patients

Evaluation and implications of mitral regurgitation using cMRI in patients with hypertrophic cardiomyopathy.

Mitral regurgitation (MR) represents an important feature in patients with hypertrophic cardiomyopathy (HCM) due to left ventricular outflow tract (LVOT) obstruction and mitral valve systolic anterior motion (SAM). Mitral valve anatomical variants associated with HCM also contribute to the severity of MR. The aim of this study is to evaluate MR severity and its correlation with different parameters in patients with HCM using cardiac magnetic resonance imaging (cMRI). 130 patients with HCM underwent cMRI. Parameters assessed for the quantification of MR severity were mitral regurgitation volume (MRV) and mitral regurgitation fraction (MRF). cMRI was also used to characterize LV function, left atrium volume (LAV) index, filling pressures and structural abnormalities associated with HCM, all in correlation to MR. Patients with HCM had mild (26.9%), moderate (52.3%) or severe (20.7%) MR. Most relevant parameters related to MR severity were MRV and MRF; other parameters with strong correlation with MR were LAV index and E/E' ratio, both increasing with its severity. Patients with LVOT obstruction had more severe MR (70.3%), 79% of them due to SAM. LV ejection fraction (LVEF) increased proportionally with the severity of MR, while LV strain (LAS) was inversely correlated with it. Independent predictors for quantifying the severity of MR, after the adjustment for covariates, were MRV, MRF, SAM, LAV index and E/E'. cMRI can accurately assess MR in patients with HCM, especially by using novel indicators, MRV and MRF respectively, along with LAV index and E/E' ratio. Severe MR, due to SAM, is more frequent in the obstructive form of HCM (HOCM). Also, the severity of MR is significantly associated with significantly associated with MRV, MRF, LAV index and E/E' ratio.

Computational fluid dynamics as a novel method to predict haemodynamic changes and guide transcatheter edge-to-edge repair.

A 78-year-old female with severe mitral regurgitation (MR) presented with heart failure. Due to the high risk of surgery, transcatheter mitral valve edge-to-edge repair (TEER) was introduced. Computational fluid dynamics (CFD) has been widely used for cardiac function assessment. Here, we investigated the haemodynamic changes by using CFD and its predictive values in TEER. The left heart system (LHS) was constructed from computed tomography and transoesophageal echocardiographic (TEE) images (Mimics 19.0, Leuven, Belgium; 3D Slicer software). The haemodynamics of LHS was calculated and visualized by 3D streamlines using the finite volume method and the combination of pressure-Implicit with splitting of operators and semi-Implicit method for pressure linked equations (PIMPLE) algorithm (OpenFOAM software) before the procedure, indicating perfect matching with the TEE view (Panel A). The reverse flow could be observed in the left atrium, and the MR fraction (MRF) calculated by CFD was 52%, similar to the echocardiographic diagnosis (MR 4+). The CFD-simulated mean mitral valve pressure gradient (MVPG) was 1.77 mmHg, consistent with echocardiography (2 mmHg).

Impact of transcatheter edge-to-edge mitral valve repair on central sleep apnoea

AimsSleep-disordered breathing (SDB) and its subtype central sleep apnoea (CSA) are highly prevalent in patients with heart failure and associated with worse prognosis. Whereas pharmacological therapy of heart failure has been shown to ameliorate CSA, results from previous studies on the effect of mitral regurgitation therapy on SDB are contradicting. The aim of this study was to assess the impact of transcatheter edge-to-edge mitral valve repair (TEER) on prevalence and severity of CSA.Methods and resultsWe enrolled 47 patients undergoing TEER for symptomatic mitral regurgitation in a prospective study. Secondary mitral regurgitation and left ventricular ejection fraction < 50% were present in 79% and 68% of patients, respectively. Respiratory polygraphy was performed before TEER in a compensated condition and four weeks after the procedure. 34 patients completed the follow-up. At baseline, 19 (56%) patients showed moderate-to-severe SDB, of whom 13 (68%) were classified as CSA. Both apnoea-hypopnoea index and percentage of recorded time spent in Cheyne-Stokes respiration strongly decreased from baseline to follow-up (median [IQR] 16 [7–30] vs. 7 [4–15] /h, p = 0.007; 6 [0–34] vs. 0 [0–8] %, p = 0.008). Median relative reduction of central apnoea index was 75% (p = 0.023), while obstructive apnoea index did not change significantly. Increase in stroke volume after TEER and high systolic pulmonary artery pressure at baseline predicted a > 50% reduction of both Apnoea-hypopnoea index and Cheyne-Stokes respiration.ConclusionTEER is associated with a significant short-term reduction of CSA and Cheyne-Stokes respiration in high-risk patients, strengthening its value as an effective treatment option for advanced heart failure.Graphical abstract

Paramètres cliniques et échocardiographiques associés à l'altération du strain longitudinal global dans l'insuffisance mitrale secondaire

IntroductionLeft ventricular systolic function may be overestimated in patients with secondary mitral regurgitation when using left ventricle ejection fraction. The Global longitudinal strain is a measure less dependent on left ventricle load. However, the clinical and echocardiographic parameters associated with the alteration of Global longitudinal strain in secondary mitral regurgitation have not been evaluated. Material and methodsA total of 96 patients (mean age 62.3 ± 12.1 years, 59.3% male) with secondary mitral regurgitation and low left ventricle ejection fraction < 50% were included. The study population was subdivided according to the Global longitudinal strain value with which an increased risk of all-cause mortality was associated (Global longitudinal strain < 7.0%, left ventricle systolic function impaired compared to Global longitudinal strain ≥ 7.0%, in absolute value). The clinical and echocardiographic endpoints are analysed in both groups of patients. ResultsThe strong and clear correlation between Global longitudinal strain (mean ± standard deviation: 7,2 ± 2,7) and parameters of systolic function (left ventricle ejection fraction mean ± standard deviation: 32,4 ± 8,0%) and contractility (dp/dt mean ± standard deviation: 682,5 ± 204,7 mmHg/s). the mean of left ventricle ejection fraction = 26.4 ± 5.3% in the Global longitudinal strain < 7 group, and the bivariate study using the 30% threshold shows that the Global longitudinal strain < 7 group presents a more altered left ventricle ejection fraction with odds ratio = 12, 5 (CI: 4.7–33.0) p < 0.001. In multivariate analysis of ultrasound parameters and linear regression shows a significant correlation between Global longitudinal strain and left ventricle ejection fraction (p < 0.001). The dp/dt analysis found a mean of 509.3 ± 99.1 mmHg/s in the Global longitudinal strain < 7 group and of 822.9 ± 154.1 in the Global longitudinal strain ≥ 7 group with significant difference (p < 0.001). In bivariate and multivariate analysis, the alteration of Global longitudinal strain is associated with a significantly lower dp / dt p < 0.001. ConclusionA Global longitudinal strain < 7 (in absolute value) reflects a severe impairment of left ventricle function. In addition, several parameters were associated with this severe alteration of the Global longitudinal strain, namely a lower left ventricle ejection fraction, a lower dp/dt and more severe symptoms permitting to characterized this group of patients in addition to an integration in a multiparametric evaluation of the secondary mitral regurgitation.

Abstract 13337: Left Atrial Ejection Fraction by Cardiac Magnetic Resonance Imaging as a Predictor of Adverse Outcomes in Patients With Advanced Ischemic Cardiomyopathy

Background: The prognostic significance of cardiac magnetic resonance (CMR) based left atrial ejection fraction (LAEF) is not well defined in the ischemic cardiomyopathy (ICM) cohort.We assess the additive effect of LAEF in a model to predict outcomes in patients with ICM. Methods: Patients with ICM, who underwent CMR between April 2001 and March 2019 were retrospectively included. Clinical characteristics and CMR parameters were collected and analyzed and LAEF was calculated in addition to myocardial infarct size (MIS) using late gadolinium enhancement (LGE) and CMR based mitral regurgitant fraction (MRF). The primary clinical endpoint was a composite of all-cause mortality and cardiac transplant. A multiple-variable Cox proportional hazards regression model which included established predictors of outcome was constructed, followed by the addition of LAEF. Four pre-specified interactions of LAEF with left ventricular end systolic volume index (LVESVi), MIS and mitral regurgitant fraction (MRF) were tested at a significance level of 0.05. RESULTS: LA functional data was measured in 718 patients. There were 416 deaths and/or transplants, with a median duration of follow up of 1763 days (4.8 years) The mean LA EF was 36 [2 ,74]. In univariate analysis, lower LAEF and higher LAVI were significant predictors of worse outcome, HR= 0.12, 95% CI [0.06, 0.25], p&lt;0.001; HR 1.008, (1.003-1.014) p = 0.003. After addition to the multivariable model, a normal LAEF was highly predictive of reduced risk, HR 0.24, (0.12, 0.48), p&lt;0.001. In the interaction between LAEF and MIS with MR Fraction, the highest risk was observed in patients with an LAEF &lt; 20% and an MIS of &gt; 30%, with MR Fraction of &gt;35%, HR of 3.2 (1.73-5.93), p= 0.009. The lowest risk was in patients with an LAEF of &gt;50% with an MIS of &lt;15 and MR Fraction of &lt;35%, HR 1.07 (0.81-1.42), p=0.009. Figure 1. CONCLUSION: Reduced LAEF is an important predictor of increased mortality in patients with ICM and additive to MIS and MR Fraction.

Abstract 10337: Early Adaptation of the Mitral Valve After St-Elevation Myocardial Infarction

Introduction: Ischemic mitral regurgitation (IMR) is associated with worse outcomes and higher mortality after myocardial infarction (MI). Clinical observations and experimental data have shown that mitral valve leaflets have the potential to enlarge over time to compensate left ventricular remodeling and prevent IMR. Previous animal studies have demonstrated that MI is associated with fibrotic changes in the mitral valve leaflets and prevent this adaptive compensation. However, the timing of mitral valve geometric changes are not well described. While previous data shows an increase in leaflet size at 6 and 12 months after MI, its short-term evolution after an ischemic event is not well documented. Methods: Twenty-two patients with ST-elevation myocardial infarction and initial left ventricular ejection fraction ≤ 45% were enrolled in Quebec Heart and Lung Institute. Participants had 3D transthoracic echocardiography (TTE) at baseline and 3 months, as well as cardiac magnetic resonance (CMR) at 3-month follow-up. Mitral valve leaflet size was measured from the 3D TTE using a custom software (Omni4D). CMR was used to derive left ventricular volumes, function and mitral regurgitant volume. Significant IMR was defined as a mitral regurgitant fraction ≥ 15% derived from the 3-month CMR. Results: Twenty-one of the 22 patients completed the imaging follow-up. Left ventricular ejection fraction at 3 months was 53 ± 10% (range from 37 to 69%). Eight patients (38%) had mild IMR at 3 months. Mitral valve surface area was significantly increased at 3 months compared with baseline for patients without IMR (10.96 ± 1.78 cm 2 vs 9.51 ± 1.62 cm 2 ; p = 0.001). Valve enlargement vs baseline was significantly greater in patients without IMR (+17 ± 13% vs -5 ± 4% for those with IMR at follow-up, p=0.0007). Conclusions: Mitral valvular surface increases within the first few months after MI, but not in all patients. Adequate valve enlargement seems related to the absence of IMR at 3 months.

Abstract 15631: Predictors of Functional Mitral Regurgitation Progression vs Regression in Patients With Non-Ischemic Cardiomyopathy: A Multi-Modality Study

Background: Functional mitral regurgitation (FMR) is associated with poor prognosis, however the determinants of FMR progression are not well understood. We aimed to determine clinical and cardiac magnetic resonance imaging (CMR) factors associated with FMR progression in patients with non-ischemic cardiomyopathy (NICM) who underwent baseline and follow-up echocardiography. Methods: NICM patients undergoing CMR between 12/2002-12/2017 with baseline (within 90 days of CMR) and follow-up echocardiography were evaluated. Progressive FMR was assessed by echocardiography based on reported FMR severity (none, mild, moderate, moderate-severe, severe). Associations between clinical and CMR parameters (left ventricular and left atrial (LA) size and function, late gadolinium enhancement, and mitral valve (MV) geometry quantification) and progressive FMR were assessed by univariable and stepwise multivariable linear regression. Results: Amongst 311 NICM patients (age 53±15.7 years, female 121 (38.9%)). A total of 17 patients (5.5%) had at least 1-grade of deterioration in FMR, while 66 patients (21.2%) had at least 1-grade of improvement. Univariable and multivariable analyses results are listed in the table. Mean baseline mitral regurgitant fraction by CMR was 14% ± 13%, while the mean of mitral regurgitation severity by echo was in the mild range (1.28 ±1). Baseline FMR grade by TTE (P&lt;0.001), CMR-LA volume indexed (P=0.003), sphericity ratio (P=0.005), MV annular mean indexed (P=0.027), and BMI (P=0.044) were independently associated with significant change in FMR. Conclusion: CMR-derived remodeling, LA and MV geometry parameters predicted progressive vs regression in FMR. Further studies are needed to determine if CMR predictors of FMR progression vs regression can improve selection criteria for procedural intervention vs guideline-directed medical therapy.

Abstract 15216: Right Ventricular Dysfunction Predictors and Prognostic Value in Ischemic and Non-Ischemic Cardiomyopathies: A Cardiac Magnetic Resonance Study

Background: Cardiac magnetic resonance imaging (CMR) is the reference standard for right ventricle (RV) quantification, however predictors and prognosis of RV dysfunction in cardiomyopathy patients, including differences between ischemic (ICM) and non-ischemic (NICM) cardiomyopathies, remain not well understood. We evaluated the factors and outcomes associated with CMR-derived reduced RV systolic function, and compared by type of cardiomyopathy. Methods: Adult cardiomyopathy patients undergoing CMR with RV quantified during 2002-2017 were retrospectively studied. Multivariable linear and Cox regression were used to identify factors associated with reduced RV ejection fraction (RVEF) and the primary endpoint (all-cause death, heart transplant or LVAD) during follow-up. Results: Amongst 771 ICM and 624 NICM patients (mean ages 62.3±11.2 and 52.8±15.9 years, 190 (24.6%) and 253 (40.5%) were female respectively), mean RVEFs were 43±14% and 43±13% respectively. The primary endpoint occurred in 455 (59.0%) ICM and 113 (18.1%) NICM patients over mean follow-up of 5.3±4.5 years. Predictors of lower RVEF in ICM were younger age, lower eGFR, lower left ventricular ejection fraction, higher right ventricular end-diastolic volume indexed and higher mitral regurgitant fraction; and in NICM were male sex, NYHA class III-IV, right bundle branch block, lower left ventricular ejection fraction, higher right ventricular end-diastolic volume and higher mitral regurgitation fraction. Reduced RVEF was associated with the primary endpoint in univariable analysis in both ICM and NICM, but only remained so for NICM in multivariable analysis of the primary endpoint as shown in the table. Conclusion: Reduced RVEF is associated with adverse prognosis, however was only independently associated with the primary endpoint in NCIM but not ICM. Key predictors of RV dysfunction in both ICM and NICM were identified, with some similar and some different predictors between them.

The value of T1 mapping in patients with chronic mitral regurgitation

Abstract Introduction The management of asymptomatic patients with severe mitral regurgitation (MR) and normal left ventricular (LV) ejection fraction (EF) remains controversial. Progressive fibrosis secondary to volume overload may explain irreversible LV dysfunction post mitral valve surgery, even in patients in which the current guidelines for intervention are applied. Considering the limitation of the LV EF as a measurement of systolic function, cardiac magnetic resonance emerges as a new technique that can detect and quantify left ventricular fibrosis before irreversible decline in LV function occurs. Late gadolinium enhancement (LGE) is a recognised method of assessing replacement fibrosis. Native T1 and post contrast administration T1 mapping provide a useful tool for measuring extracellular volume (ECV) – a marker of interstitial fibrosis. The purpose of this study was to assess the presence of myocardial fibrosis by LGE and T1 mapping in patients with moderate and severe mitral regurgitation and normal ejection fraction. Method The study group consisted of 128 consecutive patients with moderate and severe mitral regurgitation with no indication of surgery, compared with a control group of 120 patients with mild MR, studied between 2018 and 2021. Patients with contraindications to CMR were excluded. Electrocardiogram, transthoracic echocardiography and cardiac magnetic resonance, including LGE and T1 mapping were performed in all patients. Circle CVi 42 was used for image post processing and ECV calculation. Statistical analysis was performed with SPPSS 21.0. A p value &amp;lt;0.05 was considered statistically significant. Results 37 patients with MR presented with different nonischemic patterns of LGE versus 8 controls. Precontrast administration T1 mapping showed significantly higher global T1 time in patients with MR (1178±129 ms) versus controls (974±115). Mean ECV was significantly higher in patients with MR versus controls (36% vs 22%). A comparison between patients with moderate and severe MR revealed significantly higher T1 values and ECV in patients with severe MR despite normal LV EF. During the followup 15 patients required intervention. Conclusion Our study has shown that patients with moderate and severe MR that do not meet the current guidelines criteria for surgery have significantly higher T1 times and ECV compared with those with mild MR. The assessment of interstitial fibrosis using CMR T1 mapping techniques may provide an important tool in selecting patients who may benefit from early surgery before irreversible myocardial fibrotic changes occur, thus improving long term prognosis. Funding Acknowledgement Type of funding sources: None.

A preliminary analysis regarding functional mitral regurgitation grading with echocardiography and CMR: in search of similarities and resolving discordances

Abstract Background Functional mitral regurgitation (fMR) severity grading by 2D transthoracic echocardiography (TTE) can be a complex task, especially in patients where PISA assumptions are not met (eg. non-circular orifice or multiple jets). Cardiac magnetic resonance (CMR) can provide further insight on the hemodynamic burden of fMR by accurately determining mitral regurgitant fraction (RegFrac). Our goal was to investigate the concordance and disagreement between the two modalities in assessing fMR. Methodology Single-center prospective study of fMR patients performing same-day TTE and CMR from Feb to Dec 2021. MR severity was classified according to 2020 ACC consensus: grade I (mild; EROA &amp;lt;0.20 cm2), grade II (moderate; EROA 0.20–0.29 cm2), grade III (moderate-to-severe; EROA 0.30–0.39 cm2) and grade IV (severe; EROA ≥0.40 cm2). MR assessment by CMR was determined through regurgitant volume (RVol) and RegFrac quantification. A RegFrac ≥35% (recently shown as the best cut-off for prognostication) was considered hemodynamically significant. Results A total of 36 patients were included (age 65±14y; 74% male; left ventricle [LV] ejection fraction by TTE and CMR 35±13% and 34±11%, respectively). Mean RVol and EROA by TTE were 28±11mL and 0.18±0.8 cm2. Mean RVol and Regfrac by CMR were 20±13 mL and 25±12%, respectively. A moderate correlation between RVol by TTE and CMR was found (Pearson's R 0.58, p=0.001). According to TTE, there were 20 patients (56%) with grade I fMR, 12 patients (33%) with grade II fMR and 4 patients (11%) with grade III fMR. All patients considered to have mild (grade I) fMR by TTE had a RegFrac &amp;lt;35% at CMR. However, amongst those with moderate and moderate-to-severe (grades II and III) fMR, there were 8 patients (50%) with hemodynamic significant fMR (RegFrac ≥35%) at CMR – see Figure 1. Those with RegFrac ≥35% by CMR had higher indexed LV diastolic (165±24 vs 139±48 mL/m2) and systolic (116±31 vs 95±48 mL/m2) volumes and higher pulmonary artery systolic pressures (48±14 vs 41±16 mmHg) when compared with patients whose RegFrac was &amp;lt;35%, even though statistically significance was not reached. Conclusion Using the criterion of RegFrac ≥35%, CMR re-classifies (half for each side) the patients with moderate and moderate-to-severe regurgitations by TTE. Recognizing, overcoming and resolving the disagreements between the techniques is the way forward to reach excellence. Funding Acknowledgement Type of funding sources: None.

Effects of Cyproheptadine on Mitral Valve Remodeling and Regurgitation After Myocardial Infarction

BackgroundIschemic mitral regurgitation (MR) is primarily caused by left ventricle deformation, but leaflet thickening with fibrotic changes are also observed in the valve. Increased levels of 5-hydroxytryptamine (5-HT; ie, serotonin) are described after myocardial infarction (MI); 5-HT can induce valve fibrosis through the 5-HT type 2B receptor (5-HT2BR). ObjectivesThis study aims to test the hypothesis that post-MI treatment with cyproheptadine (5-HT2BR antagonist) can prevent ischemic MR by reducing the effect of serotonin on mitral biology. MethodsThirty-six sheep were divided into 2 groups: inferior MI and inferior MI treated with cyproheptadine (0.5 mg/kg/d). Animals were followed for 90 days. Blood 5-HT, infarct size, left ventricular volume and function, MR fraction and mitral leaflet size were assessed. In a complementary in vitro study, valvular interstitial cells were exposed to pre-MI and post-MI serum collected from the experimental animals. ResultsIncreased 5-HT levels were observed after MI in nontreated animals, but not in the group treated with cyproheptadine. Infarct size was similar in both groups (11 ± 3 g vs 9 ± 5 g; P = 0.414). At 90 days, MR fraction was 16% ± 7% in the MI group vs 2% ± 6% in the cyproheptadine group (P = 0.0001). The increase in leaflet size following MI was larger in the cyproheptadine group (+40% ± 9% vs +22% ± 12%; P = 0.001). Mitral interstitial cells overexpressed extracellular matrix genes when treated with post-MI serum, but not when exposed to post-MI serum collected from treated animals. ConclusionsCyproheptadine given after inferior MI reduces post-MI 5-HT levels, prevents valvular fibrotic remodeling, is associated with larger increase in mitral valve size and less MR.

Hemodynamic Modeling for Mitral Regurgitation

<h3>Purpose</h3> Mitral regurgitation (MR) is a serious valvular pathology that impacts over 2% of the total population. Despite evidence that MR poses potentially significant risks of RV dysfunction and failure, the risks of MR are mainly assessed based on left heart parameters, including the mitral regurgitant fraction (MRF) and effective regurgitant orifice area (EROA). To elucidate the links between MR and RV dysfunction, we propose a computational fluid dynamic (CFD) modeling pipeline aimed at providing a deeper understanding of the interplay between MR and RV function. <h3>Methods</h3> Dynamic CT data of a spatiotemporal motion of the patient's heart were segmented using a 3D U-Net based neural network. Meshed segmentations were propagated through time using IRTK non-rigid registration and volume preserving surface motion interpolation to recreate the motion of the patient's heart over the cardiac cycle. The 3D model was coupled to a closed loop 0D model that represents the remaining cardiovascular system and provides continuous feedback to the 3D model. This also allows the relationship between the complicated hemodynamics in the left heart and the state of the RV to be modeled. The functionality of the RV is prescribed by defining the stroke volume over the cardiac cycle. Mild, moderate, and severe MR was prescribed by defining the EROA's based on clinical parameters. <h3>Results</h3> We looked at how different MR jet areas (EROA) and RV functions pose risks to the cardiovascular system. Results from this study show that a high RV function reduces MRF at the expense of much higher right ventricle stroke work index (RVSWI) - which is strongly correlated with RV failure (Fig. 1). Variation in EROA has a lower impact on the RF and RVSWI than the RV functionality, but it does change the local hemodynamics (Fig. 2). <h3>Conclusion</h3> This process makes it possible to further understand the effect that MR has on right heart function. This is particularly important for patients who require a left ventricular assist device in which right heart failure, linked with MR, is a recognized complication.

Ex vivo biomechanical analysis of flexible versus rigid annuloplasty rings in mitral valves using a novel annular dilation system

BackgroundMitral annuloplasty rings restore annular dimensions to increase leaflet coaptation, serving a fundamental component in mitral valve repair. However, biomechanical evaluations of annuloplasty rings are lacking. We aim to biomechanically analyze flexible and rigid annuloplasty rings using an ex vivo mitral annular dilation model.MethodsJuvenile porcine mitral valves (n = 4) with intercommissural distance of 28 mm were dilated to intercommissural distances of 40 mm using a 3D-printed dilator and were sewn to an elastic mount. Fiber bragg grating sensors were anchored to native chordae to measure chordal forces. The valves were repaired using size 28 rigid and flexible annuloplasty rings in a random order. Hemodynamic data, echocardiography, and chordal force measurements were collected.ResultsMitral annular dilation resulted in decreased leaflet coaptation height and increased mitral regurgitation fraction. Both the flexible and rigid annuloplasty rings effectively increased leaflet coaptation height compared to that post dilation. Rigid ring annuloplasty repair significantly decreased the mitral regurgitation fraction. Flexible annuloplasty ring repair reduced the chordal rate of change of force (7.1 ± 4.4 N/s versus 8.6 ± 5.9 N/s, p = 0.02) and peak force (0.6 ± 0.5 N versus 0.7 ± 0.6 N, p = 0.01) compared to that from post dilation. Rigid annuloplasty ring repair was associated with higher chordal rate of change of force (9.8 ± 5.8 N/s, p = 0.0001) and peak force (0.7 ± 0.5 N, p = 0.01) compared to that after flexible ring annuloplasty repair.ConclusionsBoth rigid and flexible annuloplasty rings are effective in increasing mitral leaflet coaptation height. Although the rigid annuloplasty ring was associated with slightly higher chordal stress compared to that of the flexible annuloplasty ring, it was more effective in mitral regurgitation reduction. This study may help direct the design of an optimal annuloplasty ring to further improve patient outcomes.

Mobitz Type I as the Initial Presentation of Multisystem Inflammatory Syndrome in Children.

To The Editors: Since the emergence of the novel coronavirus SARS-CoV-2, great attention was drawn to the multisystem inflammatory syndrome in children (MIS-C) – a life-threatening complication. Although conduction disorders are uncommon in childhood, a growing number of mild cases address these abnormalities with MIS-C.1 Usually they include prolonged QTc interval, first-degree atrioventricular block (AVB), right bundle branch block, ST-segment changes and tachyarrhythmias.1 This report illustrates the importance of cardiovascular monitoring in patients with MIS-C admitted to the pediatric intensive care unit (PICU). A previously healthy 9-year-old boy presented with a high fever of 39.4°C and vomiting lasting for 4 days. He tested positive for SARS-CoV-2 by RT-PCR from a nasopharyngeal swab. On physical examination, the patient was hypotensive (blood pressure of 90/50 mm Hg) and tachycardic (heart rate of 103 beats per minute). Initial laboratory tests revealed a WBC count of 6.3 × 109/L with relative neutrophilia (85%), elevated inflammatory markers (procalcitonin of 0.949 mcg/L, C-reactive protein of 165.6 mg/L, ferritin of 280.3 mcg/L, interleukin-6 of 352.8 ng/L, fibrinogen of 7.6 g/L and D-dimers of 4.45 mg/L) and elevated cardiac markers (troponin of 0.970 mcg/L and NT-pro-BNP of 6092 ng/L). Upon sudden development of bradycardia (heart rate of 45 beats per minute), electrocardiogram (ECG) revealed Mobitz type I second-degree AVB. Echocardiography documented moderate mitral regurgitation and normal left ventricular ejection fraction without pericardial effusion. Treatment in the PICU included empiric antimicrobial therapy with ceftriaxone and clindamycin, intravenous immunoglobulins, glucocorticoids, vasopressor support and diuretics. The fever receded after 7 days. The blood cultures were negative. However, ECG raised suspicion of possible progression to more advanced blocks with a P:QRS ratio of 3:1 while the cardiac markers were still elevated (troponin of 0.062 mcg/L and NT-pro-BNP of 4110 ng/L). Serial ECG revealed spontaneous conversion to normal sinus rhythm within 3 days, confirmed by the 24-hour ECG monitoring. The patient was discharged after 14 days. At the 3- and 6-months follow-up, a 24-hour ECG recording and ergometric testing showed normal rhythm without any signs of AVB. Mobitz type I second-degree AVB secondary to MIS-C is clinically difficult to recognize due to the predominant development of hypotension and tachycardia upon admission, whereas low and irregular heart rate would be indicative of such conduction disorder in a child without MIS-C.2 Several studies explored acute cardiovascular manifestations in MIS-C where Valverde et al included 286 cases and Regan et al described serial ECGs in 63 cases with a median of 5 ECGs per patient.1,3 Neither study reported a second-degree AVB. All patients with severe MIS-C require PICU admission due to possible rapid hemodynamic deterioration. Furthermore, all patients with Mobitz type I second-degree AVB should be admitted and monitored due to possible progression to bradycardia, hypotension and/or higher degree AVB.2 In conclusion, MIS-C cases started having unique presentations, including cardiac conduction disorders. Second-degree AVB can be a presenting finding of MIS-C and high clinical suspicion must be held for patients presenting with signs of shock.

665 Longitudinal strain impairment in organic mitral regurgitation: look beyond the valve

Abstract Aims Global longitudinal strain (GLS) is a hallmark of cardiac damage in mitral regurgitation (MR). GLS &amp;gt; −18% in patients with severe organic MR (OMR) and normal LV ejection fraction (LVEF) is an independent predictor of postoperative LV dysfunction. While it is known that GLS is impaired in less than severe functional ischaemic MR (FMR), the value of GLS in less than severe OMR is not known. We aimed to determine prevalence and determinants of any GLS impairment in OMR, in comparison to FMR. Methods We retrospectively evaluated 51 consecutive patients (33 OMR and 18 FMR) with mild-to-moderate, moderate and moderate-to-severe MR (Table*). Overall, GLS was higher in OMR than FMR (17.9±4.5 vs. 10.3±5.3, P&amp;lt;0.001), with rate of impairment of 45% in OMR and 89% in FMR (P= 0.0024). Results However, no significant difference was found in GLS between mild-to-moderate, moderate and moderate-to-severe MR patients within OMR (17.7±4.7 vs. 16.9±3.9 vs. 22.4±3, respectively, P&amp;gt;0.05), as well as FMR (9.8±6.6 vs. 10.7±5.3 vs. 10.4±5.3, respectively, P&amp;gt;0.05) groups. GLS correlated directly with left ventricular (LV) ejection fraction (EF) in both OMR (r=0.69, P&amp;lt;0.001) and FMR (r=0.90, P&amp;lt;0.001), and inversely with LV mass indexed for body surface area (LVMi) in both OMR (r = −0.50, P=0.005) and FMR (r = −0.48, P=0.042). While correlation with LVEF was better for FMR than OMR (Z − 1.95, P=0.026), correlation with LVMi was similar for OMR and FMR groups (Z − 0.082, P&amp;gt;0.05). Conclusions In patients with OMR, GLS may be reduced, despite normal LVEF, in less than severe MR. Prevalence and degree of GLS impairment in OMR is less than in FMR. In OMR, as well as in FMR, GLS impairment is independent of entity of MR, but rather correlates with LVMi, maybe reflecting impact of myocardial fibrosis derived by increased LVMi on GLS.