Detection Of Myocardial Ischemia Research Articles

Dobutamine stress cardiac magnetic resonance-feature tracking in assessment of myocardial ischemia and viability

BackgroundCardiovascular magnetic resonance-feature tracking (CMR-FT) is a novel quantitative objective noninvasive technique in the assessment of myocardial deformation. The purpose of that study was to assess the capability of the CMR-FT in the detection of myocardial ischemia and viability. We investigated 30 patients (n = 480 myocardial segments), with known or suspected coronary artery disease (CAD). Dobutamine stress cardiovascular magnetic resonance (DS-CMR) and late gadolinium enhancement (LGE) were used to identify the viable non-ischemic, ischemic, and non-viable myocardial segments. Cine images at rest were used to calculate the segmental radial (Err), circumferential (Ecc), and longitudinal (Ell) strain parameters by manual contouring of endocardial and epicardial borders using Segment Software.ResultsOf the 480 myocardial segments and based on the DS-CMR and LGE results, 338 segments were defined as viable non-ischemic (remote), 101 segments were viable ischemic, and 41 segments were non-viable. Rest segmental Ecc, Err, and Ell values were significantly impaired in the non-viable (mean ± SD = − 3.94 ± 4.99%, 11.81 ± 12.55%, and − 7.50 ± 6.96%, respectively) compared to both viable groups, p < 0.001. Ecc and Err significantly differentiated between the non-ischemic and ischemic groups (mean ± SD = − 19.14 ± 7.20% vs − 13.18 ± 8.57% and 44.03 ± 19.56% vs 32.79 ± 17.91% respectively), p < 0.001. However, Ell showed no statistical significance between them (mean ± SD = − 16.44 ± 8.78% vs − 16.12 ± 10.00%, p = 0.945).ConclusionsCMR-FT can differentiate between viable and non-viable as well as ischemic and non-ischemic myocardial segments. So, such a noninvasive technique has a promising additional objective diagnostic role in conjunction with CMR in ischemia and viability assessment or even may replace stress and LGE studies in the future.

Value of Dynamic Computed Tomography Myocardial Perfusion in CAD: A Systematic Review and Meta-analysis.

Dynamic stress computed tomography (CT) perfusion is a non-invasive method for quantifying myocardial ischemia by assessing myocardial blood flow (MBF). In this meta-analysis, we evaluated the diagnostic accuracy of dynamic CT perfusion for the detection of significant coronary artery disease (CAD) across various CT scanners, obese patients, and its prognostic value. We systematically searched PubMed, Embase, Web of Science, and Cochrane library for published studies evaluating the accuracy of CT myocardial perfusion in diagnosing functional significant ischemia by invasive fractional flow reserve. The diagnostic performance of dynamic CT perfusion in detecting ischemia was evaluated using a summary receiver operating characteristic (sROC) curve. A total of 23 studies underwent meta- analysis. In myocardial region without ischemia, MBF was measured at 1.44 ml/min/g (95% confidence interval [CI]: 1.13-1.75), while in region with ischemia, it was 0.94 ml/min/g (95% CI: 0.80-1.08) (p<0.001). On the patient-based analysis, the area under the sROC curve of CT-MBF was 0.93, with a sensitivity of 0.84 and specificity of 0.88. Differences in CT type (dual source vs. single source), and body mass index (BMI) did not significantly affect the diagnostic performance. The pooled hazard ratio of dynamic CT perfusion for predicting adverse events was 4.98 (95%CI: 2.08-11.93, p=<0.001, I2=61%, p for heterogeneity = 0.07). Dynamic CT perfusion has high diagnostic performance in the quantitative assessment of ischemia and detection of functional myocardial ischemia as defined by invasive FFR, and may be useful in risk stratification of CAD patients.

Seizure and regadenoson: An underestimated concern

For 15 years, regadenoson, a selective adenosine 2A (A2A) receptor agonist, has been largely used as a pharmacologic stress agent in myocardial perfusion studies. It acts by increasing coronary blood flow. It has been shown to be non-inferior to adenosine for the detection of reversible myocardial ischemia. Regadenoson has several advantages, including less serious adverse effects, better tolerance and easier practical administration. However, specific adverse effects on the central nervous system, although rarely reported, can provocoke seizure through A2A receptor activation. We report here a case of regadenoson-associated-seizure and review the relevant literature. A 73-year-old male with a past medical history of hypertension, atrial fibrillation, stroke, hemodialysis and type 2 diabetes was referred for evaluation of hypokinesia of the apical segments. He had an unique episode of epilepsia in 2008. Less than one minute after regadenoson injection, he had a partial tonic-clonic seizure of the right upper and lower limbs, which lasted for 30seconds and resolved spontaneously. This case report is a reminder that this under-diagnosed adverse effect must be taken into consideration when using regadenoson for cardiac stress testing.

Myocardial perfusion in patients with diabetes mellitus according to stress CMR with adenosine triphosphate

Aim. To evaluate the features of myocardial perfusion according to stress CMR with adenosine triphosphate (ATP) in patients with type 2 diabetes mellitus (DM) and obstructive and non-obstructive coronary arteries (CA).Materials and Methods. Stress СMR with ATP was provided in 55 patients with a suspected or known ischemic heart disease. 39 patients of them had DM type 2. All patients were provided with invasive coronary angiography or non-invasive CT angiogram to evaluate lesions of CA. Study protocol included providing myocardial perfusion in a rest and stress with ATP in dose 160 mkg/ kg/min during 3-6 min.Results. The detection of stress-induced perfusion defects was statistically significantly associated with the obstructive CA lesions of more than 50% (p&lt;0,001). With non-obstructive CA lesions less than 50%, perfusion defects were found more often in patients with DM (36.4%) than in patients without DM (16.7%). Furthermore, the detection of stress-induced myocardial ischemia of patients with DM was not statistically significantly associated with obstructive CA (p=0,071) In case of positive result of stress CMR, patients with DM had a more widespread zone of stress-induced ischemia in the form of increase involved segments (6,45±3,78 (4,78-8,13) than patients without DM (3,17±1,60 (1,49-4,85), p=0,050).Conclusion. Patients with DM and non-obstructive CA are more likely to have a myocardial perfusion disorder than patients without DM due to coronary microvascular dysfunction.

Cardiovascular Computed Tomography in the Diagnosis of Cardiovascular Disease: Beyond Lumen Assessment.

Cardiovascular CT is being widely used in the diagnosis of cardiovascular disease due to the rapid technological advancements in CT scanning techniques. These advancements include the development of multi-slice CT, from early generation to the latest models, which has the capability of acquiring images with high spatial and temporal resolution. The recent emergence of photon-counting CT has further enhanced CT performance in clinical applications, providing improved spatial and contrast resolution. CT-derived fractional flow reserve is superior to standard CT-based anatomical assessment for the detection of lesion-specific myocardial ischemia. CT-derived 3D-printed patient-specific models are also superior to standard CT, offering advantages in terms of educational value, surgical planning, and the simulation of cardiovascular disease treatment, as well as enhancing doctor-patient communication. Three-dimensional visualization tools including virtual reality, augmented reality, and mixed reality are further advancing the clinical value of cardiovascular CT in cardiovascular disease. With the widespread use of artificial intelligence, machine learning, and deep learning in cardiovascular disease, the diagnostic performance of cardiovascular CT has significantly improved, with promising results being presented in terms of both disease diagnosis and prediction. This review article provides an overview of the applications of cardiovascular CT, covering its performance from the perspective of its diagnostic value based on traditional lumen assessment to the identification of vulnerable lesions for the prediction of disease outcomes with the use of these advanced technologies. The limitations and future prospects of these technologies are also discussed.

Diagnostic performance of angiography-derived fractional flow reserve and CT-derived fractional flow reserve: A systematic review and Bayesian network meta-analysis.

Accumulating evidence has demonstrated that fractional flow reserves (FFRs) derived from invasive coronary angiograms (CA-FFRs) and coronary computed tomography angiography-derived FFRs (CT-FFRs) are promising alternatives to wire-based FFRs. However, it remains unclear which method has better diagnostic performance. This systematic review and meta-analysis aimed to compare the diagnostic performances of the two approaches. The Cochrane Library, PubMed, Embase, Medline (Ovid), the Chinese China National Knowledge Infrastructure Database (CNKI), VIP, and WanFang Data databases were searched for relevant studies that included comparisons between CA-FFR and CT-FFR, from their respective database inceptions until January 1, 2023. Studies where both noninvasive FFR (including CA-FFR and CT-FFR) and invasive FFR (as a reference standard) were performed for the diagnosis of ischemic coronary artery disease and were designed as prospective, paired diagnostic studies, were pulled. The diagnostic test accuracy method and Bayesian hierarchical summary receiver operating characteristic (ROC) model for network meta-analysis (NMA) of diagnostic tests (HSROC-NMADT) were both used to perform a meta-analysis on the data. Twenty-six studies were included in this NMA. The results from both the diagnostic test accuracy and HSROC-NMADT methods revealed that the diagnostic accuracy of CA-FFR was higher than that of CT-FFR, in terms of sensitivity (Se; 0.86vs. 0.84), specificity (Sp; 0.90vs. 0.78), positive predictive value (PPV; 0.83vs. 0.70), and negative predictive value (NPV; 0.91vs. 0.89) for the detection of myocardial ischemia. A cumulative ranking curve analysis indicated that CA-FFR had a higher diagnostic accuracy than CT-FFR in the context of this study, with a higher area under the ROC curve (AUC; 0.94vs. 0.87). Although both of these two commonly used virtual FFR methods showed high levels of diagnostic accuracy, we demonstrated that CA-FFR had a better Se, Sp, PPV, NPV, and AUC than CT-FFR. However, this study provided only indirect comparisions; therefore, larger studies are warranted to directly compare the diagnostic performances of these two approaches.

Electrophysiological mechanisms underlying T wave pseudonormalisation on stress ECGs in hypertrophic cardiomyopathy

BackgroundPseudonormal T waves may be detected on stress electrocardiograms (ECGs) in hypertrophic cardiomyopathy (HCM). Either myocardial ischaemia or purely exercise-induced changes have been hypothesised to contribute to this phenomenon, but the precise electrophysiological mechanisms remain unknown. MethodsComputational models of human HCM ventricles (n = 20) with apical and asymmetric septal hypertrophy phenotypes with variable severities of repolarisation impairment were used to investigate the effects of acute myocardial ischaemia on ECGs with T wave inversions at baseline. Virtual 12-lead ECGs were derived from a total of 520 biventricular simulations, for cases with regionally ischaemic K+ accumulation in hypertrophied segments, global exercise-induced serum K+ increases, and/or increased pacing frequency, to analyse effects on ECG biomarkers including ST segments, T wave amplitudes, and QT intervals. ResultsRegional ischaemic K+ accumulation had a greater impact on T wave pseudonormalisation than exercise-induced serum K+ increases, due to larger reductions in repolarisation gradients. Increases in serum K+ and pacing rate partially corrected T waves in some anatomical and electrophysiological phenotypes. T wave morphology was more sensitive than ST segment elevation to regional K+ increases, suggesting that T wave pseudonormalisation may sometimes be an early, or the only, ECG feature of myocardial ischaemia in HCM. ConclusionsIschaemia-induced T wave pseudonormalisation can occur on stress ECG testing in HCM before significant ST segment changes. Some anatomical and electrophysiological phenotypes may enable T wave pseudonormalisation due to exercise-induced increased serum K+ and pacing rate. Consideration of dynamic T wave abnormalities could improve the detection of myocardial ischaemia in HCM.

The Utility of a Novel Electrocardiogram Patch Using Dry Electrodes Technology for Arrhythmia Detection During Exercise and Prolonged Monitoring: Proof-of-Concept Study.

Accurate detection of myocardial ischemia and arrhythmias during free-living exercise could play a pivotal role in screening and monitoring for the prevention of exercise-related cardiovascular events in high-risk populations. Although remote electrocardiogram (ECG) solutions are emerging rapidly, existing technology is neither designed nor validated for continuous use during vigorous exercise. In this proof-of-concept study, we evaluated the usability, signal quality, and accuracy for arrhythmia detection of a single-lead ECG patch platform featuring self-adhesive dry electrode technology in individuals with chronic coronary syndrome. This sensor was evaluated during exercise and for prolonged, continuous monitoring. We recruited a total of 6 consecutive patients with chronic coronary syndrome scheduled for an exercise stress test (EST) as part of routine cardiac follow-up. Traditional 12-lead ECG recording was combined with monitoring with the ECG patch. Following the EST, the participants continuously wore the sensor for 5 days. Intraclass correlation coefficients (ICC) and Wilcoxon signed rank tests were used to assess the utility of detecting arrhythmias with the patch by comparing the evaluations of 2 blinded assessors. Signal quality during EST and prolonged monitoring was evaluated by using a signal quality indicator. Additionally, connection time was calculated for prolonged ECG monitoring. The comfort and usability of the patch were evaluated by a web-based self-assessment questionnaire. A total of 6 male patients with chronic coronary syndrome (mean age 69.8, SD 6.2 years) completed the study protocol. The patch was worn for a mean of 118.3 (SD 5.6) hours. The level of agreement between the patch and 12-lead ECG was excellent for the detection of premature atrial contractions and premature ventricular contractions during the whole test (ICC=0.998, ICC=1.000). No significant differences in the total number of premature atrial contractions and premature ventricular contractions were detected neither during the entire exercise test (P=.79 and P=.18, respectively) nor during the exercise and recovery stages separately (P=.41, P=.66, P=.18, and P=.66). A total of 1 episode of atrial fibrillation was detected by both methods. Total connection time during recording was between 88% and 100% for all participants. There were no reports of skin irritation, erythema, or pain while wearing the patch. This proof-of-concept study showed that this innovative ECG patch based on self-adhesive dry electrode technology can potentially be used for arrhythmia detection during vigorous exercise. The results suggest that the wearable patch is also usable for prolonged continuous ECG monitoring in free-living conditions and can therefore be of potential use in cardiac rehabilitation and tele-monitoring for the prevention of exercise-related cardiovascular events. Future efforts will focus on optimizing signal quality over time and conducting a larger-scale validation study focusing on both arrhythmia and ischemia detection.

Abstract 14203: Speckle Tracking Analysis During Dobutamine Stress Echocardiography in Patients Undergoing Percutaneous Coronary Intervention for Chronic Total Occlusion

Background: Dobutamine stress echocardiography (DSE) is often used as a non-invasive diagnostic modality for detection of myocardial ischemia and viability. A “biphasic response” in DSE can occur, in which contractility improves in dysfunctional segments with low dose stage and then becomes dysfunctional again at higher doses due to ischemia. We investigated if speckle tracking analysis during DSE can evaluate patients undergoing percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). Methods: DSE was performed one day before CTO-PCI in consecutive 30 patients (18 female, age=71±11 years). Since 27 patients had 1 vessel, and 3 patients had 2 vessel CTO lesions, total of 33 regions were analyzed. Global (GLS) and regional longitudinal strain (RLS) were calculated as an averaged value of peak longitudinal strain in the apical 4-, 2-chamber, and long axis views at baseline echo, at low-dose, at high-dose DSE, and 6 months after CTO-PCI using available software (QLAB, Philips Medical Systems). Results: CTO-PCI was successfully done in all patients. GLS and RLS were feasible in all regions. Overall, GLS (-15.5±2.8 at baseline v.s. -17.3±3.8, p&lt;0.001) and left ventricular ejection fraction (LVEF) (56±6% v.s. 58±7%, p&lt;0.01) significantly improved 6 months after CTO-PCI. There was also significant improvement of RLS for the obstructed CTO regions (-13.8±3.6 v.s. -16.5±4.2, p&lt;0.005). Although in 24 patients (26 regions) with biphasic response during DSE (Figure), GLS (-15.7±2.5 v.s. -17.9±3.6, p&lt;0.01), LVEF (54±6% v.s. 56±7%, p&lt;0.05), and RLS (-13.8±3.5 v.s. -16.8±4.0, p&lt;0.01) improved significantly, GLS (-14.9±4.2 v.s. -15.8±5.0, p=n.s.), LVEF (59±3% v.s. 60±3%, p=n.s.), and RLS (-13.9±4.5 v.s. -15.5±5.7, p=n.s.) didn’t change in 6 patients (7 regions) without biphasic response. Conclusion: Speckle tracking analysis is feasible during DSE. CTO-PCI may improve both global and regional cardiac functions in patients with myocardial viability.

Stress-only versus rest-stress SPECT MPI in the detection and diagnosis of myocardial ischemia and infarction by machine learning.

Rest-stress SPECT myocardial perfusion imaging (MPI) is widely used to evaluate coronary artery disease (CAD). We aim to evaluate stress-only versus rest-stress MPI in diagnosing CAD by machine learning (ML). A total of 276 patients with suspected CAD were randomly divided into training (184 patients) and validation (92 patients) cohorts. Variables extracted from clinical, physiological, and rest-stress SPECT MPI were screened. Stress-only and rest-stress MPI using ML were established and compared using the training cohort. Then the diagnostic performance of two models in diagnosing myocardial ischemia and infarction was evaluated in the validation cohort. Six ML models based on stress-only MPI selected summed stress score, summed wall thickness score of stress%, and end-diastolic volume of stress as key variables and performed equally good as rest-stress MPI in detecting CAD [area under the curve (AUC): 0.863 versus 0.877, P = 0.519]. Furthermore, stress-only MPI showed a reasonable prediction of reversible deficit, as shown by rest-stress MPI (AUC: 0.861). Subsequently, nomogram models using the above-stated stress-only MPI variables showed a good prediction of CAD and reversible perfusion deficit in training and validation cohorts. Stress-only MPI demonstrated similar diagnostic performance compared with rest-stress MPI using 6 ML algorithms. Stress-only MPI with ML models can diagnose CAD and predict ischemia from scar.

Instantaneous detection of acute myocardial infarction and ischaemia from a single carotid pressure waveform in rats.

Myocardial infarction (MI) is one of the leading causes of death worldwide. It is well accepted that early diagnosis followed by early reperfusion therapy significantly increases the MI survival. Diagnosis of acute MI is traditionally based on the presence of chest pain and electrocardiogram (ECG) criteria. However, around 50% of the MIs are without chest pain, and ECG is neither completely specific nor definitive. Therefore, there is an unmet need for methods that allow detection of acute MI or ischaemia without using ECG. Our hypothesis is that a hybrid physics-based machine learning (ML) method can detect the occurrence of acute MI or ischaemia from a single carotid pressure waveform. We used a standard occlusion/reperfusion rat model. Physics-based ML classifiers were developed using intrinsic frequency parameters extracted from carotid pressure waveforms. ML models were trained, validated, and generalized using data from 32 rats. The final ML models were tested on an external stratified blind dataset from additional 13 rats. When tested on blind data, the best ML model showed specificity = 0.92 and sensitivity = 0.92 for detecting acute MI. The best model's specificity and sensitivity for ischaemia detection were 0.85 and 0.92, respectively. We demonstrated that a hybrid physics-based ML approach can detect the occurrence of acute MI and ischaemia from carotid pressure waveform in rats. Since carotid pressure waveforms can be measured non-invasively, this proof-of-concept pre-clinical study can potentially be expanded in future studies for non-invasive detection of MI or myocardial ischaemia.

Ultra-High-Resolution Electrocardiography Enables Earlier Detection of Transmural and Subendocardial Myocardial Ischemia Compared to Conventional Electrocardiography.

The sensitivity of exercise ECG is marginally sufficient for the detection of mild reduction of coronary blood flow in patients with early coronary atherosclerosis. Here, we describe the application of a new technique of ECG registration/analysis-ultra-high-resolution ECG (UHR ECG)-for early detection of myocardial ischemia (MIS). The utility of UHR ECG vs. conventional ECG (C ECG) was tested in anesthetized rats and pigs. Transmural MIS was induced in rats by the ligation of the left coronary artery (CA). In pigs, subendocardial ischemia of a variable extent was produced by stepwise inflation of a balloon within the right CA, causing a 25-100% reduction of its lumen. In rats, a reduction in power spectral density (PSD) in the high-frequency (HF) channel of UHR ECG was registered at 60 s after ischemia (power 0.81 ± 0.14 vs. 1.25 ± 0.12 mW at baseline, p < 0.01). This was not accompanied by any ST segment elevation on C ECG. In pigs, PSD in the HF channel of UHR ECG was significantly decreased at a 25% reduction of CA lumen, while the ST segment on C ECG remained unchanged. In conclusion, UHR ECG enabled earlier detection of transmural MIS compared to C ECG. PSD in the HF channel of UHR ECG demonstrated greater sensitivity in the settings of subendocardial ischemia.

Changes in circulating ApoJ-Glyc levels in patients with suspected acute coronary syndrome: The EDICA trial

BackgroundMyocardial ischemia induces intracellular accumulation of non-glycosylated apolipoprotein J that results in a reduction of circulating glycosylated ApoJ (ApoJ-Glyc). The latter has been suggested to be a marker of transient myocardial ischemia. ObjectiveThis proof-of-concept clinical study aimed to assess whether changes in circulating ApoJ-Glyc could detect myocardial ischemia in patients attending the emergency department (ED) with chest pain suggestive of acute coronary syndrome (ACS). MethodsIn suspected ACS patients, EDICA (Early Detection of Myocardial Ischemia in Suspected Acute Coronary Syndromes by ApoJ-Glyc a Novel Pathologically based Ischemia Biomarker), a multicentre, international, cohort study assessed changes in 2 glycosylated variants of ApoJ-Glyc, (ApoJ-GlycA2 and ApoJ-GlycA6), in serum samples obtained at ED admission (0 h), and 1 h and 3 h thereafter, blinded to the clinical diagnosis (i.e. STEMI, NSTEMI, unstable angina, non-ischemic). Results404 patients were recruited; 291 were given a clinical diagnosis of “non-ischemic” chest pain and 113 were considered to have had an ischemic event. ApoJ-GlycA6 was lower on admission in ischemic compared with “non-ischemic” patients (66 [46–90] vs. 73 [56–95] μg/ml; P = 0.04). 74% of unstable angina patients (all with undetectable hs-Tn), had ischemic changes in ApoJ-Glyc at 0 h and 89% at 1 h. Initially low ApoJ-Glyc levels in 62 patients requiring coronary revascularization increased significantly after successful percutaneous intervention. ConclusionsCirculating ApoJ-Glyc concentrations decrease early in ED patients with myocardial ischemia compared with “non-ischemic” patients, even in the absence of troponin elevations. ApoJ-Glyc may be a useful marker of myocardial ischemia in the ED setting.

Post hoc labeling an acute ECG as ischemic or non-ischemic based on clinical data: A necessary challenge

The ECG is crucial in the prehospital (and early inhospital) phase of patients with symptoms suggestive of myocardial ischemia. Therefore, new algorithms for ECG-based myocardial ischemia detection are continuously being researched. Development and validation of these algorithms require a database of acute ECGs (from the prehospital or emergency department setting) including a representative mix of cases (ischemia present) and controls (no ischemia present). Therefore, for every patient in this mix, the “truth” regarding the actual presence or absence of myocardial ischemia during the recording of the acute ECG has to be determined to compare the newly developed algorithm against. This post hoc adjudication process of determining whether an acute (either prehospitally acquired or acquired in the emergency department) ECG was made under ischemic conditions should use all available clinical data (the clinical diagnosis, cardiac imaging data, and laboratory values) of the subsequent patient's admission.Even with all data at hand, post hoc labeling a patient and their acute ECG as a myocardial ischemia case or control cannot be forced into a binary division between definite cases and definite controls. More specifically, to be used for the development of a new algorithm, the patients' ECG has to be scored for the presence or absence of myocardial ischemia at the exact moment of its recording, which renders the classification even more difficult. For instance, even though it may be plausible that myocardial ischemia was present at a given moment during the patient's admission, this is not necessarily proof that the prehospital (or early inhospital) ECG was also made in ischemic conditions: ischemia can be a fluctuating process (as is, e.g., the case in unstable angina pectoris). Therefore, post hoc classification of an acute ECG in terms of the absence or presence of ischemia requires a multipoint scale ranging between definite ischemic to definite non-ischemic, for instance using a 5-point scale (presumed non-ischemic, probably non-ischemic, uncertain, probably ischemic, presumed ischemic).To summarize, the post hoc adjudication process of ECGs of ambulance (and emergency department) patients cannot result in a binary division into definite cases and controls (i.e., patients with or without myocardial ischemia during the recording of the acute ECG), as myocardial ischemia is often dynamic rather than constant. ECGs could be labeled on a multi-point scale, in which the label represents the probability of the actual presence (or absence) of myocardial ischemia at the exact moment of the recording of that ECG. Further development of algorithms for myocardial ischemia detection should consider this concept.

Advanced repeated structuring and learning procedure to detect acute myocardial ischemia in serial 12-lead ECGs

Objectives. Acute myocardial ischemia in the setting of acute coronary syndrome (ACS) may lead to myocardial infarction. Therefore, timely decisions, already in the pre-hospital phase, are crucial to preserving cardiac function as much as possible. Serial electrocardiography, a comparison of the acute electrocardiogram with a previously recorded (reference) ECG of the same patient, aids in identifying ischemia-induced electrocardiographic changes by correcting for interindividual ECG variability. Recently, the combination of deep learning and serial electrocardiography provided promising results in detecting emerging cardiac diseases; thus, the aim of our current study is the application of our novel Advanced Repeated Structuring and Learning Procedure (AdvRS&LP), specifically designed for acute myocardial ischemia detection in the pre-hospital phase by using serial ECG features. Approach. Data belong to the SUBTRACT study, which includes 1425 ECG pairs, 194 (14%) ACS patients, and 1035 (73%) controls. Each ECG pair was characterized by 28 serial features that, with sex and age, constituted the inputs of the AdvRS&LP, an automatic constructive procedure for creating supervised neural networks (NN). We created 100 NNs to compensate for statistical fluctuations due to random data divisions of a limited dataset. We compared the performance of the obtained NNs to a logistic regression (LR) procedure and the Glasgow program (Uni-G) in terms of area-under-the-curve (AUC) of the receiver-operating-characteristic curve, sensitivity (SE), and specificity (SP). Main Results. NNs (median AUC = 83%, median SE = 77%, and median SP = 89%) presented a statistically (P value lower than 0.05) higher testing performance than those presented by LR (median AUC = 80%, median SE = 67%, and median SP = 81%) and by the Uni-G algorithm (median SE = 72% and median SP = 82%). Significance. In conclusion, the positive results underscore the value of serial ECG comparison in ischemia detection, and NNs created by AdvRS&LP seem to be reliable tools in terms of generalization and clinical applicability.

Detection of Myocardial Ischemia Using Cardiovascular MRI Stress T1 Mapping: A Miniature-Swine Validation Study

Purpose To assess the efficacy of cardiac MRI stress T1 mapping in detecting ischemic and infarcted myocardium in a miniature-swine model, using pathologic findings as the reference standard. Materials and Methods Ten adult male Chinese miniature swine, with coronary artery stenosis induced by an ameroid constrictor, and two healthy control swine were studied. Cardiac 3-T MRI rest and adenosine triphosphate stress T1 mapping and perfusion images, along with resting and late gadolinium enhancement images, were acquired at baseline and weekly up to 4 weeks after surgery or until humanely killed. A receiver operating characteristic analysis was used to analyze the performance of T1 mapping in the detection of myocardial ischemia. Results In the experimental group, both the infarcted myocardium (ΔT1 = 10 msec ± 2 [SD]; ΔT1 percentage = 0.7% ± 0.1) and ischemic myocardium (ΔT1 = 10 msec ± 2; ΔT1 percentage = 0.9% ± 0.2) exhibited reduced T1 reactivity compared with the remote myocardium (ΔT1 = 53 msec ± 7; ΔT1 percentage = 4.7% ± 0.6) and normal myocardium (ΔT1 = 56 msec ± 11; ΔT1 percentage = 4.9% ± 1.1). Receiver operating characteristic analysis demonstrated high diagnostic performance of ΔT1 in detecting ischemic myocardium, with an area under the curve (AUC) of 0.84 (P < .001). Rest T1 displayed high diagnostic performance in detecting infarcted myocardium (AUC = 0.95; P < .001). When rest T1 and ΔT1 were combined, the diagnostic performance for both ischemic and infarcted myocardium were improved (AUCs, 0.89 and 0.97, respectively; all P < .001). The collagen volume fraction correlated with ΔT1, ΔT1 percentage, and Δ extracellular volume percentage (r = −0.70, −0.70, and −0.50, respectively; P = .001, .001, and .03, respectively). Conclusion Using histopathologic validation in a swine model, noninvasive cardiac MRI stress T1 mapping demonstrated high performance in detecting ischemic and infarcted myocardium without the need for contrast agents. Keywords: Coronary Artery Disease, MRI, Myocardial Ischemia, Rest T1 Mapping, Stress T1 Mapping, Swine Model Supplemental material is available for this article. © RSNA, 2023 See also commentary by Burrage and Ferreira in this issue.

The use of a new ECG patch for exercise and prolonged monitoring: usability, evaluation of signal quality and utility to detect arrhythmias

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ITEA. Background Accurate detection of myocardial ischemia and arrhythmia’s during free-living exercise could play a pivotal role in optimizing screening and monitoring of individuals with underlying cardiovascular disease. Although remote electrocardiogram (ECG) solutions are emerging rapidly, these applications are generally not designed nor validated for continuous use during vigorous exercise. Purpose In this proof-of-concept study, we evaluated the usability, signal quality and arrhythmia detection of a new self-adhesive dry electrode ECG patch, the Nighthawk Vital Signs patch, during exercise and prolonged continuous ECG monitoring in individuals with chronic coronary syndrome (CCS). Methods Six consecutive CCS patients scheduled for an exercise stress test as part of routine cardiac follow-up were recruited. The traditional 12-lead exercise ECG was combined with monitoring with the 1-lead patch. Following the exercise test, the subjects continuously wore the sensor for five days. Intraclass correlation coefficients (ICC) and Wilcoxon signed-rank tests were used to assess the utility to detect arrhythmias with the patch. Signal quality for ECG recording was evaluated by using a signal quality indicator (SQI) based on the average QRS complex. Connection time and signal-to-noise ratio (SNR) were additionally calculated for prolonged ECG monitoring. Comfort and usability of the patch were evaluated by an online questionnaire. Results Six male patients with CCS (mean age 69.8 ± 6.2 years) completed the protocol. The mean time the patch was worn, was 118.3 hours (SD 5.6). The level of agreement between the patch and the 12-lead ECG was excellent for amount of premature atrial contractions (PAC’s) and premature ventricular contractions (PVC’s) during exercise stage, recovery stage and total test duration (ICC = 0.998, 0.998, 1.000, 1.000, 0.998, 1.000). There were no significant differences in the total amount of PAC’s and PVC’s detected with both methods during the exercise test (p = 0.785 and 0.180, respectively). One episode of atrial fibrillation was detected identically on both recorded ECG’s. Signal quality based on average QRS SQI during exercise did decrease slightly during (sub)maximal effort. Total connection time during recording was above 88% in all subjects and the SNR was above the target limit of 18dB. There were no reports on skin irritation, erythema or pain. Conclusion The Nighthawk Vital Signs ECG patch based on self-adhesive dry electrodes technology can be used for accurate arrhythmia detection during vigorous exercise. The sensor is also usable for prolonged ECG monitoring in free-living conditions and can therefore be of potential use in cardiac rehabilitation and telemonitoring for prevention of exercise-related cardiovascular events. However, more research is needed in order to analyze the signal quality over time together with a larger-scale validation study focusing on both arrhythmia and ischemia detection.

SILENT MYOCARDIAL ISCHEMIA IN PATIENTS WITH ACUTE CORONARY SYNDROME AND DIABETES MELLITUS

ST-segment elevation myocardial infarction, stenting of the infarct-related coronary artery, silent (painless) myocardial ischemia, diabetes mellitus, 24-hour electrocardiographic monitoring.&#x0D; Introduction. Currently, approximately 422 million people in the world have diabetes mellitus, and over 1.3 million individuals in Ukraine are diagnosed with diabetes mellitus. Diabetic neuropathy is known to contribute to the development of atypical and painless variants of ischemic heart disease in individuals with diabetes. This poses a challenge for timely diagnosis and obscures the course of ischemic heart disease, as the prevalence of silent myocardial ischemia is significantly high in these patients. Therefore, the aim of this study is to investigate the occurrence of myocardial ischemia episodes in patients with ST-elevation myocardial infarction within the first day following stenting of the infarct-related coronary artery. Furthermore, we aimed to demonstrate the painless nature of these episodes in the presence of type 2 diabetes mellitus through a clinical case presentation.&#x0D; Materials and methods. 30 patients with ST-segment elevation myocardial infarction were examined, and 24-hour electrocardiographic monitoring was performed during the first day after the infarct-related coronary artery stenting. Results. Episodes of transient myocardial ischemia were registered in 50% of people. We found that the majority of episodes (80%) were painless. In the presence of diabetes mellitus, only episodes of painless myocardial ischemia were noted that is supported by the example of a clinical case. The study highlighted the informativeness of 24-hour electrocardiographic monitoring in identifying episodes of myocardial ischemia, particularly in its painless variant. The results demonstrate that patients with ST-elevation myocardial infarction (STEMI) experience episodes of transient myocardial ischemia within the first day after coronary artery stenting, with a majority of these episodes being painless. Furthermore, in the presence of diabetes mellitus, ischemic episodes tend to be painless. Therefore, 24-hour electrocardiographic monitoring serves as a valuable method for the detection of myocardial ischemia.

Technical challenges and innovative solutions for bedside alarms

The guidelines advocate, in patients with chest pain, comparison of the acute ECG with a previously made, non-ischemic ECG that serves as a reference, to corroborate the working diagnosis of acute coronary syndrome (ACS). Our approach of this serial comparison is to compute the differences between the ST vectors at the J point and 60 ms thereafter (∆ST(J + 0), ∆ST(J + 60)) and between the ventricular gradient (VG) vectors (∆VG). In the current study, we investigate if reference ECGs remain valid in time.We studied 6 elective non-ischemic ECGs (ECG0, ECG1, …, ECG5), 5 years apart, in 88 patients. Within each patient, serial comparisons were done 1) between all successive ECGs, and 2) between each of ECG1, ECG2, …, ECG5 and ECG0, computing, in addition to ∆ST(J + 0), ∆ST(J + 60) and ∆VG, the difference in heart rates, ∆HR. Additionally, relevant clinical events and the diagnoses associated with each ECG were collected. Linear regression was used to assess trends in ∆ST(J + 0), ∆ST(J + 60) and ∆VG; multiple linear regression was used to assess the influence of the clinical events and diagnoses on ∆ST(J + 0), ∆ST(J + 60) and ∆VG.There were no trends in the differences between successive ECGs. Positive trends were seen with increasing time lapses between ECGs: ∆ST(J + 0), ∆ST(J + 60) and ∆VG increased per year by 0.65 μV, 1.45 μV and 3.69 mV∙ms, respectively. Extrapolation to a time lapse of 0 yielded 50.92 μV, 36.63 μV and 20.91 mV∙ms for the short-term reproducibility of ∆ST(J + 0), ∆ST(J + 60) and ∆VG, respectively. Multiple linear regression revealed that clinical variables could explain only 10%, 17% and 13% of the variability in ∆ST(J + 0), ∆ST(J + 60) and ∆VG, respectively.With a view on ischemia detection thresholds in the order of magnitude of 58 μV for ∆ST and 26 mV·ms for ∆VG, our study suggests that it is important to have a recent ECG available for the detection of myocardial ischemia, as an “aged” ECG may have lost its validity as a reference.

Validation of the detection of ischemia using 12 lead smartphone based electrocardiography - a non-randomized, single blinded, cross-sectional, multicenter study

Background: Reliable and early detection of myocardial ischemia using computer-aided analysis of electrocardiograms (ECG) provides an important reference for early diagnosis of CVD. We developed a 12-lead smartphone-based electrocardiogram (ECG) acquisition and monitoring system (called “Spandan”), and an application to assess underlying ischemia from analysis of electrocardiographic (ECG) signals only. Objectives of this study were to validate the Spandan 12 lead ECG interpretation for accuracy in the detection of Ischemia in comparison to cardiologists’ diagnosis and to evaluate the accuracy of ischemia in comparison to the interpretation of standard 12 lead ECG. Methods: In this multi-center study all patients (n=597) visiting the ECG room at the department of cardiology were enrolled in the study by taking their written consent and explaining the purpose of the study. Results: Mean age was 52.85 years. The male gender (n=344, 57.62%) shows the maximum frequency than female gender. 12 lead Spandan smartphone ECG recorded fewer false positive cases (8 versus 230) and identified greater true negative cases (310 versus 115). Spandan smartphone ECG recorded better specificity (97.4% versus 33.3%) and positive predictive value (87.4% versus 51.4%) as compared to gold standard ECG. The accuracy of interpretation of Ischemia by cardiologists diagnosis through 12 lead Spandan smartphone ECG was better (100%) as compared gold standard (95.3%). Conclusions: Our study highlights the potential of Spandan smartphone ECG in the detection of myocardial ischemia. This may improve patient satisfaction and reduce healthcare costs.