The role of the ECG in diagnosis, risk estimation, and catheterization laboratory activation in patients with acute coronary syndromes: a consensus document

Advancements in Artificial Intelligence for Precision Diagnosis and Treatment of Myocardial Infarction: A Comprehensive Review of Clinical Trials and Randomized Controlled Trials

Coronary artery disease (CAD) is still a serious global health issue that has a substantial impact on death and illness rates. The goal of primary prevention strategies is to lower the risk of developing CAD. Nevertheless, current methods usually rely on simple risk assessment instruments that might overlook significant individual risk factors. This limitation highlights the need for innovative methods that can accurately assess cardiovascular risk and offer personalized preventive care. Recent advances in machine learning and artificial intelligence (AI) have opened up interesting new avenues for optimizing primary preventive efforts for CAD and improving risk prediction models. By leveraging large-scale databases and advanced computational techniques, AI has the potential to fundamentally alter how cardiovascular risk is evaluated and managed. This review looks at current randomized controlled studies and clinical trials that explore the application of AI and machine learning to improve primary preventive measures for CAD. The emphasis is on their ability to recognize and include a range of risk elements in sophisticated risk assessment models.

A Narrative Review of the Classical and Modern Diagnostic Methods of the No-Reflow Phenomenon

The incidence of the no-reflow (NR) phenomenon varies depending on the diagnostic criteria used. If just the angiographic criteria are considered (i.e., a degree of thrombolysis in myocardial infarction ≤2), it will be found that the incidence of NR is quite low; on the other hand, when the myocardial NR is taken into account (i.e., a decrease in the quality of myocardial reperfusion expressed by the degree of myocardial blush), the real incidence is higher. Thus, the early establishment of a diagnosis of NR and the administration of specific treatment can lead to its reversibility. Otherwise, regardless of the follow-up period, patients with NR have a poor prognosis. In the present work, we offer a comprehensive perspective on diagnostic tools for NR detection, for improving the global management of patients with arterial microvasculature damage, which is a topic of major interest in the cardiology field, due to its complexity and its link with severe clinical outcomes.

Novel ECG features and machine learning to optimize culprit lesion detection in patients with suspected acute coronary syndrome

BACKGROUND

Novel temporal-spatial features of the 12‑lead ECG can conceptually optimize culprit lesions' detection beyond that of classical ST amplitude measurements. We sought to develop a data-driven approach for ECG feature selection to build a clinically relevant algorithm for real-time detection of culprit lesion.

METHODS

This was a prospective observational cohort study of chest pain patients transported by emergency medical services to three tertiary care hospitals in the US. We obtained raw 10-s, 12‑lead ECGs (500 s/s, HeartStart MRx, Philips Healthcare) during prehospital transport and followed patients 30 days after the encounter to adjudicate clinical outcomes. A total of 557 global and lead-specific features of P-QRS-T waveform were harvested from the representative average beats. We used Recursive Feature Elimination and LASSO to identify 35/557, 29/557, and 51/557 most recurrent and important features for LAD, LCX, and RCA culprits, respectively. Using the union of these features, we built a random forest classifier with 10-fold cross-validation to predict the presence or absence of culprit lesions. We compared this model to the performance of a rule-based commercial proprietary software (Philips DXL ECG Algorithm).

RESULTS

Our sample included 2400 patients (age 59 ± 16, 47% female, 41% Black, 10.7% culprit lesions). The area under the ROC curves of our random forest classifier was 0.85 ± 0.03 with sensitivity, specificity, and negative predictive value of 71.1%, 84.7%, and 96.1%. This outperformed the accuracy of the automated interpretation software of 37.2%, 95.6%, and 92.7%, respectively, and corresponded to a net reclassification improvement index of 23.6%. Metrics of ST80; Tpeak-Tend; spatial angle between QRS and T vectors; PCA ratio of STT waveform; T axis; and QRS waveform characteristics played a significant role in this incremental gain in performance.

CONCLUSIONS

Novel computational features of the 12‑lead ECG can be used to build clinically relevant machine learning-based classifiers to detect culprit lesions, which has important clinical implications.

Culprit lesion detection in patients presenting with non-ST elevation acute coronary syndrome and multivessel disease

BACKGROUND/PURPOSE

Identification of the culprit lesion in patients with non-ST elevation acute coronary syndrome (NSTE-ACS) allows appropriate coronary revascularization but may be unclear in patients with multivessel coronary disease (MVD). Therefore, we investigated the rate of culprit lesion identification during coronary angiography in NSTE-ACS and multivessel disease.

METHODS/MATERIALS

Consecutive patients presenting with NSTE-ACS and MVD, between January 2012 and December 2016 were evaluated. Coronary angiograms, intravascular imaging, and ECGs were analyzed for culprit lesion identification. Long-term clinical outcomes in terms of major adverse cardiac events (MACE) and mortality were reported in patients with or without culprit identification.

RESULTS

A total of 1107 patients with NSTE-ACS and MVD were included in the analysis, 310 (28.0%) with unstable angina and 797 (72.0%) with non-ST elevation myocardial infarction. The culprit lesion was angiographically identified in 952 (86.0%) patients, while no clear culprit lesion was found in 155 (14.0%) patients. ECG analysis allowed to predict the location of the culprit vessel with low sensitivity (range 28.4%-36.7%) and high specificity (range 90.6%-96.5%). Higher lesion complexity was associated with inability to identify the culprit. Intravascular imaging was applied in 55 patients and helped to identify the culprit lesion in 53 patients (96.4%). There was no difference in all-cause mortality (21.4% vs. 25.8%, p = 0.24) and MACE (39.2% vs. 47.6%, p = 0.07) between the cohorts with or without culprit lesion identification by angiography.

CONCLUSIONS

The culprit lesion appeared unclear by coronary angiography in >10% of patients with NSTE-ACS and MVD. Complementary invasive imaging substantially enhanced the diagnostic accuracy of culprit lesion detection.

A counterpoint paper: Comments on the electrocardiographic part of the 2018 Fourth Universal Definition of Myocardial Infarction endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology

The Fourth Universal Definition of Myocardial Infarction (FUDMI) focuses on the distinction between nonischemic myocardial injury and myocardial infarction (MI), along with the role of cardiovascular magnetic resonance, in order to define the etiology of myocardial injury. As a consequence, there is less emphasis on updating the parts of the definition concerning the electrocardiographic (ECG) changes related to MI. Evidence of myocardial ischemia is a prerequisite for the diagnosis of MI, and the ECG is the main available tool for (a) detecting acute ischemia, (b) triage, and (c) risk stratification upon presentation. This review focuses on multiple aspects of ECG interpretation that we firmly believe should be considered for incorporation in any future update to the Universal Definition of MI.

Electrocardiographic identification of the culprit coronary artery in acute non-ST-elevation myocardial infarction: predictive value of N-wave and T-wave precordial instability

BACKGROUND

Recently, novel ischemic electrocardiographic changes have been described, which may be clinically significant in the identification of the culprit coronary vessel in patients with non-ST-elevation myocardial infarction (NSTEMI). We sought to determine the predictive value of N-wave, T-wave precordial instability, de-Winter ST/T-wave complex, and inferolateral myocardial infarction in the identification of the culprit artery in patients with NSTEMI referred for early invasive (<24 h) treatment.

METHODS

A total of 148 patients with NSTEMI, aged 40-91 years, were enrolled from a cohort of 510 consecutive NSTEMI subjects, hospitalized in our center in 2015-2017.

RESULTS

Of the evaluated ischemic ECG changes, the most common finding in patients with culprit left circumflex (LCx)/obtuse marginal artery or right coronary artery was T-wave precordial instability (28.3 and 13.5%, respectively), whereas in individuals with culprit left anterior descending/diagonal artery, T-wave precordial instability and N-wave in leads II, III or aVF occurred equally often (16.0%). A significant relationship was found between the occurrence of N-wave in inferolateral leads and culprit LCx/obtuse marginal. In multivariable analysis, N-wave in lead aVL [odds ratio (OR) 2.10; 95% confidence interval (CI), 1.15-3.81], and T-wave precordial instability (OR 1.56; 95% CI, 1.02-2.41) were independent predictors of culprit LCx/obtuse marginal. The accuracy of N-wave in lead aVL in predicting the culprit LCx/obtuse marginal was 73.9% and was higher than the accuracy of T-wave precordial instability, which was 69.1%.

CONCLUSIONS

In patients with NSTEMI referred for early invasive treatment, the presence of N-wave or T-wave precordial instability may be of greater clinical importance in the prediction of culprit LCx/obtuse marginal than classic ischemic changes.

A counterpoint paper: Comments on the electrocardiographic part of the 2018 Fourth Universal Definition of Myocardial Infarction

The Fourth Universal Definition of Myocardial Infarction (FUDMI) [published simultaneously in 2018 in numerous journals including Circulation, Journal of the American College of Cardiology and European Heart Journal] focuses mainly on the distinction between non-ischemic myocardial injury and myocardial infarction (MI), along with the role of cardiovascular magnetic resonance, in order to define the etiology of myocardial injury. As a consequence, there is less emphasis on updating the parts of the definition concerning the electrocardiographic (ECG) changes related to MI. Evidence of myocardial ischemia is a prerequisite for the diagnosis of MI and the ECG is the main available tool for i) detecting acute ischemia, ii) triage and iii) risk stratification upon presentation. This review focuses on multiple aspects of ECG interpretation that we firmly believe should be considered for incorporation in any future update to the Universal Definition of MI. Our counterpoint view is that: a) the use of the ECG following coronary artery bypass surgery should be better explored and defined; b) the emphasis in the FUDMI on convex versus concave ST-elevation, which is questionable, should be balanced by the fact that many patients with true ST-elevation MI (STEMI) present with a concave form of ST elevation; c) reciprocal ST-depression in STEMI caused by right coronary artery or left circumflex artery occlusion, should be set against the fact that not all anterior STEMIs present with reciprocal ST-depression which can also be seen in cardiomyopathy and left ventricular hypertrophy; d) the "posterior" leads V7-V9 should be placed on a horizontal line from V4, rather than follow the 5th intercostal space; e) ST-depression in V1-V3 is not a manifestation of ischemia of the basal inferior segment, placed horizontally; f) Interpreting ST-T changes in patients with conduction abnormalities and pacemakers should be further defined.

Emergency Department Chest Pain Patients With or Without Ongoing Pain: Characteristics, Outcome, and Diagnostic Value of the Electrocardiogram

BACKGROUND

In emergency department (ED) chest pain patients, it is believed that the diagnostic accuracy of the electrocardiogram (ECG) for acute coronary syndrome (ACS) is higher during ongoing than abated chest pain.

OBJECTIVES

We compared patient characteristics and the diagnostic performance of the ECG in ED patients presenting with ongoing, vs. abated, chest pain.

METHODS

In total, 1132 unselected ED chest pain patients were analyzed. The patient characteristics and diagnostic accuracy for index visit ACS of the emergency physicians' interpretation of the ECG was compared in patients with and without ongoing chest pain. Logistic regression analysis was performed to control for possible confounders.

RESULTS

Patients with abated chest pain (n = 508) were older, had more comorbidities, and had double the risk of index visit ACS (15%) and major adverse cardiac events (MACE) at 30 days (15.6%) compared with patients with ongoing pain (n = 631; ACS 7.3%, 30-day MACE 7.4%). Sensitivity of the ECG for ACS was 24% in patients with ongoing pain and 35% in those without, specificity was 97% in both groups, negative predictive value was 94% and 89%, respectively, and positive likelihood ratio 10.6 and 7.8, respectively. When the diagnostic performance was controlled for confounders, there was no significant difference between the groups.

CONCLUSION

Our results indicate that ED chest pain patients with ongoing pain at arrival are younger, healthier, and have less ACS and 30-day MACE than patients with abated pain, but that there is no difference in the diagnostic accuracy of the ECG for ACS between the two groups.

Diagnostic and prognostic value of ST-segment deviation scores in suspected acute myocardial infarction

BACKGROUND

Recent advances in digital electrocardiography technology allow evaluating ST-segment deviations in all 12 leads as quantitative variables and calculating summed ST-segment deviation scores. The diagnostic and prognostic utility of summed ST-segment deviation scores is largely unknown.

METHODS

We aimed to explore the diagnostic and prognostic utility of the conventional and the modified ST-segment deviation score (Better Analysis of ST-segment Elevations and Depressions in a 12- Lead-ECG-Score (BASEL-Score): sum of elevations in the augmented voltage right - lead (aVR) plus absolute, unsigned ST-segment depressions in the remaining leads) in patients presenting with suspected non-ST-segment elevation myocardial infarction. The diagnostic endpoint was non-ST-segment elevation myocardial infarction, adjudicated by two independent cardiologists. Prognostic endpoint was mortality during two-year follow up.

RESULTS

Among 1330 patients, non-ST-segment elevation myocardial infarction was present in 200 (15%) patients. Diagnostic accuracy for non-ST-segment elevation myocardial infarction as quantified by the area under the receiver-operating-characteristics curve was significantly higher for the BASEL-Score (0.73; 95% confidence interval 0.69-0.77) as compared to the conventional ST-segment deviation score (0.53; 95% confidence interval 0.49-0.57, p<0.001). The BASEL-Score provided additional independent diagnostic value to dichotomous electrocardiogram variables (ST-segment depression, T-inversion, both p<0.001) and to high-sensitivity cardiac troponin (p<0.001) as well as clinical judgment at 90 min (p<0.001). Similarly, only the BASEL-Score proved to be an independent predictor of two year mortality.

CONCLUSIONS

The modified ST-segment deviation score BASEL-Score focusing on ST-segment elevation in aVR and ST-segment depressions in the remaining leads provides incremental diagnostic and prognostic information.

ECG analysis in patients with acute coronary syndrome undergoing invasive management: rationale and design of the electrocardiography sub-study of the MATRIX trial

BACKGROUND

The twelve‑lead electrocardiogram (ECG) has become an essential tool for the diagnosis, risk stratification, and management of patients with acute coronary syndromes (ACS). However, several areas of residual controversies or gaps in evidence exist. Among them, P-wave abnormalities identifying atrial ischemia/infarction are largely neglected in clinical practice, and their diagnostic and prognostic implications remain elusive; the value of ECG to identify the culprit lesion has been investigated, but validated criteria indicating the presence of coronary occlusion in patients without ST-elevation are lacking; finally, which criteria among the multiple proposed, better define pathological Q-waves or success of revascularisation deserve further investigations.

METHODS

The Minimizing Adverse hemorrhagic events via TRansradial access site and systemic Implementation of AngioX (MATRIX) trial was designed to test the impact of bleeding avoidance strategies on ischemic and bleeding outcomes across the whole spectrum of patients with ACS receiving invasive management. The ECG-MATRIX is a pre-specified sub-study of the MATRIX programme which aims at analyzing the clinical value of ECG metrics in 4516 ACS patients (with and without ST-segment elevation in 2212 and 2304 cases, respectively) with matched pre and post-treatment ECGs.

CONCLUSIONS

This study represents a unique opportunity to further investigate the role of ECGs in the diagnosis and risk stratification of ACS patients with or without ST-segment deviation, as well as to assess whether the radial approach and bivalirudin may affect post-treatment ECG metrics and patterns in a large contemporary ACS population.

Comparison of Electrocardiographic Characteristics in Men Versus Women ≤ 55 Years With Acute Myocardial Infarction (a Variation in Recovery: Role of Gender on Outcomes of Young Acute Myocardial Infarction Patients Substudy)

Young women with acute myocardial infarction (AMI) have a worse prognosis than their male counterparts. We searched for differences in the electrocardiographic presentation of men and women in a large, contemporary registry of young adults with AMI that could help explain gender differences in outcomes. The qualifying electrocardiogram was blindly assessed by a central core lab in 3,354 patients (67% women) aged 18 to 55 years included in the Variation in Recovery: Role of Gender on Outcomes of Young AMI Patients study. Compared with men, women did not have a different frequency of sinus rhythm, and they had shorter PR and QRS intervals and longer QTc intervals. Intraventricular conduction disturbances were not different among genders. Notably, women were more likely than men to have abnormal Q waves in anterior leads and a lower frequency of Q waves in other territories. ST-segment elevation myocardial infarction (STEMI) diagnosis was less frequent in women than in men (44.6% vs 55.1%, p < 0.001). Among patients with STEMI, women had less magnitude and extent of ST-segment elevation than men. In patients with non-STEMI, the frequency, magnitude, and extent of ST-segment depression were not different among genders, but women had anterior ST-segment depression less frequently and anterior negative T waves more frequently compared with men. These differences remained statistically significant after adjusting for baseline characteristics. In conclusion, there are significant gender differences in the electrocardiographic presentation of AMI among young patients. Further studies are warranted to evaluate their impact on gender-related differences in the management and outcomes of AMI.

Evaluation of left ventricular longitudinal deformation in patients with and without ST segment depression during supraventricular tachycardia

BACKGROUND

The cumulative effect of repeated demand ischemia on left ventricular (LV) systolic function has been previously demonstrated. We evaluated the longitudinal deformation of LV myocardial fibers at systole and diastole using two-dimensional speckle-tracking echocardiography (2DSTE) in patients with and without ST-segment depression during supraventricular tachycardia.

METHODS

We recruited 104 consecutive patients, who were admitted to our hospital for the ablation of atrioventricular nodal reentrant tachycardia or atrioventricular reentrant tachycardia. The patients were thereafter evaluated by transthoracic echocardiography and 2DSTE, and longitudinal systolic strain and strain rate as well as early and late diastolic strain rates were measured.

RESULTS

We found no statistically significant differences in longitudinal systolic strain and strain rate as well as in early and late diastolic strain rates between the two study groups.

CONCLUSIONS

The longitudinal deformation properties of LV muscle fibers were not different between patients with and without ST-segment depression during supraventricular tachycardia. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:343-349, 2017.

2017 ISHNE-HRS expert consensus statement on ambulatory ECG and external cardiac monitoring/telemetry

Ambulatory ECG (AECG) is very commonly employed in a variety of clinical contexts to detect cardiac arrhythmias and/or arrhythmia patterns which are not readily obtained from the standard ECG. Accurate and timely characterization of arrhythmias is crucial to direct therapies that can have an important impact on diagnosis, prognosis or patient symptom status. The rhythm information derived from the large variety of AECG recording systems can often lead to appropriate and patient-specific medical and interventional management. The details in this document provide background and framework from which to apply AECG techniques in clinical practice, as well as clinical research.

Comments on the 2015 ESC Guidelines for the Management of Acute Coronary Syndromes in Patients Presenting Without Persistent ST-segment Elevation

Patients who have undergone angioplasty with stenting can be reintegrated into normal life at an early stage, thanks to the absence of sequelae associated with the procedure itself. Consequently, these patients can be involved earlier in the second stage of cardiac rehabilitation. Although rehabilitation for coronary patients follows the general guidelines used for all patients, which were developed with the secondary prevention of coronary artery atherosclerosis in mind, the specific form of rehabilitation adopted for each individual with ischemic heart disease will depend on the patient's circumstances, including the revascularization technique used. Regular physical exercise (i.e. physical training), in itself, has substantial cardiovascular benefits for both primary and secondary cardiovascular prevention. In patients who have had a myocardial infarction, training decreases mortality, increases functional capacity and improves ventricular function and remodeling. It is also thought to boost the collateral circulation. In addition, training improves endothelial function and stimulates the circulation of stem cells. It has been shown that physical training after percutaneous revascularization decreases the number of cardiac events. Moreover, in patients with stable angina, it results in fewer events than percutaneous revascularization.

Electrocardiographic findings during balloon angioplasty of the left circumflex coronary artery - influence of location of the ischemic segments with respect to the obtuse margin of the left ventricle

BACKGROUND

Acute left circumflex coronary artery (LCx) occlusion is not easily detected by the standard 12-lead electrocardiogram (ECG).

METHODS

In 16 patients continuous ECG recording was performed during balloon occlusion. The treated lesions were divided into proximal and distal based on the location of the ischemic segments with respect to the left obtuse margin of the heart.

RESULTS

Mean ΔST (=ST amplitude during inflation - pre-inflation ST) ≥0.5mm in both leads I and aVL predicted a proximal occlusion site with sensitivity of 62.5% (95% confidence interval [CI] 24.9-91.5%), specificity 100% (95% CI 63.1-100%), positive predictive value 100% (95% CI 47.8-100%), and negative predictive value 72.7% (95% CI 39-94%). In lead III, mean ΔST was +0.3mm in the distal and -0.2mm in the proximal group, respectively (p=0.036).

CONCLUSIONS

ST elevation in leads I and aVL is associated with myocardial ischemia at or proximal to the left obtuse margin.

The Role of Transmural Repolarization Gradient in the Inversion of Cardiac Electric Field: Model Study of ECG in Hypothermia

BACKGROUND

The changes in ventricular repolarization gradients lead to significant alterations of the electrocardiographic body surface T waves up to the T wave inversion. However, the contribution of a specific gradient remains to be elucidated. The objective of the present investigation was to study the role of the transmural repolarization gradient in the inversion of the body surface T wave with a mathematical model of the hypothermia-induced changes of ventricular repolarization.

METHODS

By means of mathematical simulation, we set the hypothermic action potential duration (APD) distribution on the rabbit ventricular epicardium as it was previously experimentally documented. Then the parameters of the body surface potential distribution were tested with the introduction of different scenarios of the endocardial and epicardial APD behavior in hypothermia resulting in the unchanged, reversed or enlarged transmural repolarization gradient.

RESULTS

The reversal of epicardial repolarization gradients (apicobasal, anterior-posterior and interventricular) caused the inversion of the T waves regardless of the direction of the transmural repolarization gradient. However, the most realistic body surface potentials were obtained when the endocardial APDs were not changed under hypothermia while the epicardial APDs prolonged. This produced the reversed and increased transmural repolarization gradient in absolute magnitude. The body surface potentials simulated under the unchanged transmural gradient were reduced in comparison to those simulated under the reversed transmural gradient.

CONCLUSIONS

The simulations demonstrated that the transmural repolarization gradient did not play a crucial role in the cardiac electric field inversion under hypothermia, but its magnitude and direction contribute to the T wave amplitude.

Clinical Significance of Upsloping ST Depression on Resting Electrocardiogram

INTRODUCTION

Upsloping ST depression is generally not associated with myocardial ischemia, yet there have been published reports that suggest otherwise.

CASE HISTORY

A 34-year-old pregnant female presented with chest pain and palpitations. She was found to have supraventricular tachycardia, which resolved with intravenous adenosine. Few minutes later her ECG showed upsloping ST depression in leads V4-V6 that persisted for 1 hour after the resolution of the tachycardia. The patient was discharged in stable condition with outpatient follow-up.

CONCLUSION

Upsloping ST depression in resting electrocardiogram may indicate cardiac ischemia in the presence of active cardiac symptoms. In the absence of ongoing symptoms however, it may be secondary to conditions other than ischemia.