Investigation of clinical significance of ST-segment depression during paroxysmal supraventricular tachycardia.

INTRODUCTION: There are great differences in ST-segment depression during PSVT episodes. The aim of this study is to investigate the clinical significance of ST segment depression during PSVT. METHODS: The study enrolled 333 consecutive patients who were diagnosed with PSVT by electrophysiological test from Jan 1, 2021 to July 31, 2022. The range, magnitude and morphology of ST-segment depression were described. The correlation between ST-segment depression and symptoms of chest tightness, chest pain or hypotension, the correlation between ST-segment depression and coronary stenosis, and the possible influencing factors were analyzed. In addition, the diagnostic efficacy of ST-segment depression for AVRT was determined. RESULTS: ST-segment depression was present in 85% of patients, in 70% of which the depression range was more than six leads. The magnitude of the depression was more significant in precordial leads (P < 0.001). ST-segment depression of >1 mm in limb leads and precordial leads was found in 36.0% and 49.8% of the patients, respectively, while >3 mm was found in 2.4% and 9.6%, respectively. The morphology of ST-segment depression in limb leads was different from that in precordial leads (P < 0.001). Downsloping ST-segment depression was more common in limb leads (limb vs. precordial: 40.5% vs. 12.6%), whereas upsloping depression was more common in precordial leads (limb vs. precordial: 3.0% vs. 23.1%). Correlation analysis showed that ST-segment depression was not correlated with symptoms of chest tightness and pain, nor was it correlated with coronary artery stenosis. The most important influencing factor is the type of PSVT, especially affecting the morphology of depression in limb leads (OR = 10.27 [5.93-17.79], P < 0.001). The sensitivity and specificity of downsloping ST-segment depression in limb leads for diagnosis of AVRT were 75.5% and 76.7%. CONCLUSION: ST-segment depression is a common ECG change during PSVT episodes, and it's not associated with severe coronary stenosis. The type of PSVT has a significant effect on the manifestation of ST-segment depression. The downslope morphology of ST-segment depression in limb leads is helpful in differentiating AVRT from AVNRT.

Short-term effects of ambient gaseous air pollution on blood platelet mitochondrial DNA methylation and myocardial ischemia.

BACKGROUND: The potential effects of short-term exposure to major ambient gaseous pollutants (ozone: O3, carbon monoxide: CO, and sulfur dioxide: SO2) on platelet mitochondrial DNA (mtDNA) methylation have been uncertain and no studies have examined whether platelet mtDNA methylation levels could modify the associations between ambient gaseous pollutants and the risks of ST-segment depression (STDE) and T-wave inversion events (TIE), two indicators of myocardial ischemia. METHODS: This study used data from a randomized, double-blind, placebo-controlled intervention study with a standardized 24-hour exposure protocol among 110 participants in Beijing. Absolute changes in platelet mtDNA methylation (ACmtDNAm) levels were determined by two repeated measurements on platelet mtDNA methylation levels in blood samples collected before and after the 24-hour exposure period. A multivariable linear regression model and a generalized linear model with a Poisson link function were used to investigate the associations of ambient gaseous pollutants with platelet mtDNA methylation levels, STDE, and TIE, respectively. RESULTS: Short-term O3 exposure was significantly associated with decreased ACmtDNAm at ATP6_P1 but increased ACmtDNAm at mt12sRNA, MT-COX1, and MT-COX1_P2; short-term CO and SO2 exposures were significantly associated with decreased ACmtDNAm at D-loop, MT-COX3- and ATP-related genes. Moreover, short-term O3 exposure was significantly associated with increased risks of STDE and TIE, and ACmtDNAm at MT-COX1 and MT-COX1_P2 modified the association between short-term O3 exposure and STDE events. L-Arg supplementation attenuated the effects of ambient gaseous pollutants, particularly O3, on ACmtDNAm and STDE. CONCLUSIONS: Platelet mtDNA methylation levels are promising biomarkers of short-term exposure to ambient gaseous air pollution, and are likely implicated in the mechanism behind the association of ambient O3 pollution with adverse cardiovascular effects. L-Arg supplementation showed the potential to mitigate the adverse effects of ambient O3 pollution.

A New Inherited Syndrome Causing Sudden Cardiac Death with Distinct ST-Segment Depression and Ankyrin-2-Mutation.

Introduction: Sudden cardiac death (SCD) is a serious threat. In individuals under the age of 35 years sudden arrhythmic death is the most frequent cause. In younger persons, genetically determined cardiac diseases (eg, cardiomyopathies and ion-channel diseases) account for an important proportion of these cases. Methods: We investigated the case of a 23-year-old male with SCD, specific ECG changes and left ventricular hypertrophy. Family history was significant for SCD in the paternal line. A precise analysis was performed by an international multidisciplinary expert panel including autopsy of the index patient's heart, molecular autopsy, whole-exome sequencing, analysis of the pedigree and examination of available family members. Results: Three cases of SCD were reported in paternal relatives. The index patient exhibited specific ECG changes (ST-depression), which were also found in five paternal relatives and the brother of the index patient. Post-mortem analysis of the heart yielded mild idiopathic concentric hypertrophy without myocardial disarray. The genetic analysis of the index patient showed two nucleotide variations in two different genes (ANK2: c.11791G>A, MYO18B: c.3761G>A), which were also expressed in five relatives. Two family members had showed all indicators of the inherited syndrome including distinct ECG changes and genetic changes. Conclusion: We describe a distinct inheritable syndrome causing SCD, characterized by specific ECG changes and mutations of ANK2 and MYO18. As far as we know this is the first description of this syndrome.

Atypical Electrocardiogram in Acute Pericarditis: A Case Report.

Pericarditis is a disorder defined by inflammation of the pericardium, commonly presenting with chest pain, fever, and pericardial friction. Electrocardiography (EKG) is frequently utilized to diagnose pericarditis, as it frequently reveals particular changes like ST-segment elevations and PR-segment depressions. Nevertheless, there are cases where individuals show all symptoms of pericarditis yet present an atypical or irregular EKG. This case report intends to highlight the case of a patient who came to an outpatient medical facility with all the common symptoms of pericarditis yet presented an atypical electrocardiogram. Moreover, this report intends to look into the hypothesis that in patients showing symptoms of pericarditis but with an atypical EKG, we might be looking at an irregular or even non-specific variant of pericarditis. This highlights the value of an extensive diagnostic approach consisting of high-quality imaging studies, such as transthoracic echocardiography, as well as medical assessments if an EKG does not give definite proof of pericarditis.

Acute coronary syndrome with simultaneous two-vessel occlusion De Winter ST-segment depression or reciprocal change?

We discuss a case of acute coronary syndrome (ACS) with simultaneous two-vessel occlusions in a man in his 20s. The serial electrocardiograms (ECG) showed very early dynamic changes of ST-T configuration resulting from ischemic zone depth or area between anterior wall versus inferior wall. The upsloping ST depression along with tall tentorial T waves in the precordial leads, as shown in the index ECG, raises the possibilities of a de Winter pattern. The retrospective assessment of the index ECG identified prominent T waves and a mild degree of ST-segment elevations in the inferior leads, given the electrocardiographic findings previously recorded at his workplace medical examination obtained at a later date. If the subtle ST-segment elevations in leads II, III, and aVF and the tall T waves were not overlooked in the index ECG, the probability of reciprocal ST-segment depressions in the precordial leads should also be taken into account. We recognize our ECG findings as intriguing ST-T deviation patterns that can change depending on the time sequence and anatomical dominancy of two infarct-related arteries. We finally suggest physicians should bear in mind the possibility of simultaneous multiple vessel occlusions when they encounter ACS patients with hemodynamic instability as in this present case.

Clinical significance of ST-segment depression during atrial fibrillation rhythm for subsequent heart failure events.

Aims: The clinical significance of ST-segment depression during atrial fibrillation (AF) rhythm has not been fully evaluated. The aim of the present study was to explore the association of ST-segment depression during AF rhythm with subsequent heart failure (HF) events. Methods and results: The study enrolled 2718 AF patients whose baseline electrocardiography (ECG) was available from a Japanese community-based prospective survey. We assessed the association of ST-segment depression in baseline ECG during AF rhythm with clinical outcomes. The primary ednpoint was a composite HF endpoint: cardiac death or hospitalization due to HF. The prevalence of ST-segment depression was 25.4% (upsloping 6.6%, horizontal 18.8%, downsloping 10.1%). Patients with ST-segment depression were older and had more comorbidities than those without. During the median follow-up of 6.0 years, the incidence rate of the composite HF endpoint was significantly higher in patients with ST-segment depression than those without (5.3% vs. 3.6% per patient-year, log-rank P < 0.01). The higher risk was present in horizontal or downsloping ST-segment depression, but not in upsloping one. By multivariable analysis, ST-segment depression was an independent predictor for the composite HF endpoint (hazard ratio 1.23, 95% confidence interval 1.03-1.49, P = 0.03). In addition, ST-segment depression at anterior leads, unlike inferior or lateral leads, was not associated with higher risk for the composite HF endpoint. Conclusion: ST-segment depression during AF rhythm was associated with subsequent HF risk; however, the association was affected by type and distribution of ST-segment depression.

CineECG analysis provides new insights into Familial ST-segment Depression Syndrome.

AIMS: Familial ST-segment Depression Syndrome (Fam-STD) is a novel inherited cardiac disease associated with arrhythmias and sudden cardiac death. This study aimed at investigating the cardiac activation pathway in patients with Fam-STD, modelling the electrocardiogram (ECG) phenotype, and performing in-depth ST-segment analyses. METHODS AND RESULTS: CineECG analysis of patients with Fam-STD and age- and sex-matched controls. The groups were compared using the CineECG software which included the trans-cardiac ratio and the electrical activation pathway. We simulated the Fam-STD ECG phenotype by adjusting action potential duration (APD) and action potential amplitude (APA) in specific cardiac regions. High-resolution ST-segment analyses were performed per lead by dividing the ST-segment into nine 10 ms subintervals. Twenty-seven Fam-STD patients (74% females, mean age 51.6 ± 6.2 years) and 83 matched controls were included. Among Fam-STD patients, electrical activation pathway analysis in the anterior-basal orientation showed significantly abnormal direction toward the basal areas of the heart starting from QRS 60-89 ms until Tpeak-Tend (all P < 0.001). Simulations with shortened APD and reduced APA in the left ventricle basal regions recapitulated the Fam-STD ECG phenotype. Detailed ST-segment analyses showed significant differences in all nine 10 ms subintervals (all P < 0.01), with the most prominent findings during the 70-79/80-89 ms intervals. CONCLUSION: CineECG analyses indicated abnormal repolarization with basal directions, and the Fam-STD ECG phenotype was simulated by reducing APD and APA in the left ventricle basal regions. Detailed ST-analysis showed amplitudes consistent with the proposed diagnostic criteria for Fam-STD patients. Our findings provide new insight into the electrophysiological abnormalities of Fam-STD.

Relationship between pre-procedural non-ischemic ST-segment depression and the clinical outcomes after catheter ablation in persistent atrial fibrillation patients.

BACKGROUND: ST-segment depression suggests the presence of coronary artery disease (CAD) during sinus rhythm, but the clinical significance, including the outcomes after catheter ablation (CA), in atrial fibrillation (AF) patients remain unknown. METHODS: The present study included persistent AF (PerAF) patients from the Osaka Rosai Atrial Fibrillation ablation (ORAF) registry who underwent an initial ablation and had no history of CAD. We assigned the patients based on the presence of ST-segment depression before CA and evaluated the impact of relevant factors on ST-segment depression and the relationship between ST-segment depression, including leads locations (anterior leads, inferior leads, and lateral leads) or depression type (upsloping, horizontal, and downsloping) or the degree of ST-segment depression and late recurrence of AF (LRAF). RESULTS: This study population included a total of 551 patients of whom 189 had ST-segment depression. The median follow-up duration was 397 days and LRAF occurred in 195 patients. By multiple regression analysis, diabetes mellitus, hemoglobin, brain natriuretic peptide, left ventricular ejection fraction, and left atrial diameter were significant determinants of ST-segment depression before CA. Kaplan-Meier analysis demonstrated that the patients with ST-segment depression had a significantly greater risk of LRAF than those without (p < 0.001). Multivariate Cox proportional hazards analysis showed ST-segment depression was independently and significantly associated with a higher risk of LRAF (p < 0.001). The patients with ST-segment depression ≥0.15 mV had a significantly higher risk of LRAF than those with ST-segment depression ≥0.15 mV (p < 0.001). No significant differences among the ST-segment depression lead locations and ST-segment depression type were observed. CONCLUSION: Non-ischemic ST-segment depression during AF rhythm was significantly associated with LRAF post CA in PerAF patients.

ECGs in Critical Care Cardiology: Do Not Miss That Myocardial Infarction.

This paper provides clinical cases of acute myocardial infarction that do not show ST-segment elevation on 12-lead electrocardiogram, but should be clinically treated as ST-segment elevation myocardial infarction with early diagnostic coronary angiogram followed by appropriate strategy of revascularization. (Level of Difficulty: Beginner.).

Clinical significance and prognostic value of ST segment depression on ECG during exercise treadmill test in asymptomatic patients with moderate or severe aortic stenosis.

Objectives. In patients with asymptomatic moderate or severe aortic stenosis (AS), exercise testing is used for evaluating the need for aortic valve intervention. Expert opinions about the clinical significance and prognostic value of ST segment depression on electrocardiography (ECG) during exercise testing in AS is conflicting and there are no large studies exploring this issue. We aimed to explore the association of ST segment depression >5 mm during exercise treadmill test (ETT) with all-cause mortality, aortic valve replacement (AVR) or cardiac-related hospitalization. Design. We performed a retrospective analysis of prospectively collected data of a total of 315 patients (mean age 65 ± 12 years, 67% men) with asymptomatic moderate (n = 209; 66%) or severe (n = 106; 34%) AS. All patients underwent clinical evaluation, echocardiography and ETT. Results. During a mean follow-up of 34.9 ± 34.6 months, 29 (9%) patients died and 235 (74%) underwent AVR. The prevalence of ST segment depression (>5 mm) was 13% (n = 41) in the total study population and was comparable in patients with revealed symptoms (17.6%, n = 16) versus without revealed symptoms (11.3%, n = 25; p = .132). ST segment depression on ETT was strongly associated with aortic valve area. In univariate Cox regression analysis, ST segment depression was not associated with cardiac related hospitalizations (HR 1.65; 95% CI 0.89-3.10, p = .113), all-cause mortality (HR 1.37; 95% CI 0.47-3.98, p = .564) or AVR (HR 1.30; 95% CI 0.89-1.91, p = .170). Conclusion. In patients with moderate or severe AS, ST segment depression during ETT is non-specific, carries no prognostic risk and should be used with caution in the clinical interpretation of exercise test.

Increased Incidence of ECG Abnormalities in the General Population During the COVID-19 Pandemic.

To examine the effect of the COVID-19 pandemic on the cardiovascular system in the general population, we compared ECG changes after the onset of the COVID-19 pandemic with those before the pandemic period. The incidence of newly appeared ECG abnormalities (T wave abnormalities, ST-segment depression including minor changes, and abnormal Q waves) from 2019 to 2020 (COVID-19 period) was compared with that from 2018 to 2019 (control period) in subjects 40 to 74 years of age without a history of cardiovascular disease who had 12-lead ECG recordings during annual health checkups offered to adult citizens of Moriguchi City, Osaka, Japan. Logistic regression analyses were performed after adjusting for cardiovascular risk factors. There were 5,221 eligible subjects in the control period and 4,100 eligible subjects in the COVID-19 period. The incidences of newly appeared ECG abnormalities were 5.2% for T wave abnormalities, 2.8% for ST-segment depression, and 1.1% for abnormal Q waves in the control period, whereas they were 5.8%, 4.3%, and 1.7% respectively, in the COVID-19 period. The incidence of ST-segment depression (odds ratio (OR) = 1.59, 95% confidence interval (CI) = 1.27-1.98, P < 0.0001) and that of abnormal Q waves (OR = 1.56, 95%CI = 1.09-2.22, P = 0.0149) in the COVID-19 period were significantly higher compared to those of the control period. In conclusion, increased incidences of newly appeared ST-segment depression and abnormal Q waves were observed during the COVID-19 pandemic period.

Subepicardial burn injuries in bullfrog heart induce electrocardiogram changes mimicking inferior wall myocardial infarction.

Using bullfrog hearts, we previously reproduced a ST segment elevation in electrocardiogram (ECG), mimicking human ischemic heart disease. In the present study, by inducing subepicardial burn injuries on the inferior part of the frog heart ventricle, we could reproduce typical ECG changes observed in human inferior wall myocardial infarction, such as the marked elevation of the ST segments in inferior limb leads (II, III, aVF) and their reciprocal depression in the opposite limb leads (I, aVL). Due to the decrease in Na+/K+-ATPase protein expression, the resting membrane potential of injured cardiomyocytes shifted toward depolarization. Such induced electrical difference between the injured and intact cardiomyocytes was thought to be responsible for the creation of "currents of injury" and the subsequent ST segment changes.

Transient ascending ST-segment depression and widening of the S wave in 3-channel Holter monitoring-A sign of dromotropic disturbance in the right ventricular outflow tract in the Brugada syndrome: A report of five cases.

BACKGROUND: Brugada syndrome (BrS) is somewhat a challenging diagnosis, due to its dynamic pattern. One of the aspects of this disease is a significant conduction disorder located in the right ventricular outflow tract (RVOT), which can be explained as a consequence of low expression of Connexin-43. This decreased conduction speed is responsible for the typical electrocardiographic pattern. Opposite leads located preferably in inferior leads of the electrocardiogram may show a deep and widened S wave associated with ascending ST segment depression. Holter monitoring electrocardiographic (ECG) aspects is still a new frontier of knowledge in BrS, especially in intermittent clinical presentations. METHODS: We describe, as an exploratory analysis, five case series of intermittent type 1 BrS to demonstrate the appearance of ascending ST segment depression and widening of the S wave, during 3-channel 24h-Holter monitoring (C1, C2 and C3) with bipolar leads. RESULTS: In the five cases described, the ST segment depression was observed mainly in C2, but in some cases also in C1 and C3. Only case 1 presented concomitant intermittent elevation of the ST segment in C1. All cases were intermittent. CONCLUSION: The recognition of an ECG pattern with ascending ST-segment depression and widening of the S wave in 3-channel Holter described in this case series should raise a suspicion of the BrS and suggests the counterpart of a dromotropic disturbance registered in the RVOT and/or reciprocal changes.

ST-segment depression in atrioventricular nodal reentrant tachycardia: Preliminary results.

BACKGROUND: The ST-segment is part of the electrocardiogram and physiologically, it forms an isoelectric line. The ST-segment depression is often observed in young, healthy people with paroxysmal tachycardia with narrow QRS complexes. In this group of patients, the 'mysterious tachycardia-induced ST-segment depression', 'subendocardial myocardial ischemia' and other not fully understood terms are used to explain this phenomenon. OBJECTIVES: To assess the presence and possible mechanisms of ST-segment depression during atrioventricular nodal reentrant tachycardia (AVNRT) in patients undergoing radiofrequency (RF) ablation of the underlying arrhythmia. MATERIAL AND METHODS: The study included 50 patients (35 women and 15 men) aged about 49 years with clinically relevant paroxysmal narrow QRS complex tachycardia. During electrophysiological study (EPS), all patients had measured QRS components - QR, RS and RJ during the tachycardia and during the sinus rhythm. All of the measurements were done in lead V5. RESULTS: There was a statistically significant difference in cycle length during sinus rhythm and tachycardia (707.0 ±137.8 ms compared to 327.5 ±29.1 ms, p = 0.000), the RJ component (0.819 ±0.381 mV compared to 0.878 ±0.376 mV, p = 0.003) and the difference RJ-QR (0.081 ±0.083 mV compared to 0.163 ±0.108 mV, p = 0.000). The differences in RS and QR components during sinus rhythm and tachycardia did not reach the statistical significance. The difference RJ-QR during tachycardia correlated negatively with tachycardia cycle length (R = -0.39, p = 0.0049). The tachycardia cycle length correlated positively with the age of the studied patients (R = 0.28, p = 0.043). CONCLUSION: In patients with AVNRT, there is a ST-segment depression during the episodes of tachycardia and the degree of this change is related to tachycardia cycle length. The most probable explanation of the ST-segment depression is the overlap of the QRS complex on the preceded T wave. Some intrinsic properties of individual electrocardiogram (ECG) also influence this phenomenon. The ischemic origin of the presented ST-segment change can be excluded.

Ischemic ST-Segment Depression Maximal in V1-V4 (Versus V5-V6) of Any Amplitude Is Specific for Occlusion Myocardial Infarction (Versus Nonocclusive Ischemia).

Background Occlusion myocardial infarctions (OMIs) of the posterolateral walls are commonly missed by ST-segment-elevation myocardial infarction (STEMI) criteria, with >50% of patients with circumflex occlusion not receiving emergent reperfusion and experiencing increased mortality. ST-segment depression maximal in leads V1-V4 (STDmaxV1-4) has been suggested as an indicator of posterior OMI. Methods and Results We retrospectively reviewed a high-risk population with acute coronary syndrome. OMI was defined from prior studies as a culprit lesion with TIMI (Thrombolysis in Myocardial Infarction) 0 to 2 flow or TIMI 3 flow plus peak troponin T >1.0 ng/mL or troponin I >10 ng/mL. STEMI was defined by the Fourth Universal Definition of Myocardial Infarction. ECGs were interpreted blinded to outcomes. Among 808 patients, there were 265 OMIs, 108 (41%) meeting STEMI criteria. A total of 118 (15%) patients had "suspected ischemic" STDmaxV1-4, of whom 106 (90%) had an acute culprit lesion, 99 (84%) had OMI, and 95 (81%) underwent percutaneous coronary intervention. Suspected ischemic STDmaxV1-4 had 97% specificity and 37% sensitivity for OMI. Of the 99 OMIs detected by STDmaxV1-4, 34% had <1 mm ST-segment depression, and only 47 (47%) had accompanying STEMI criteria, of which 17 (36%) were identified a median 1.00 hour earlier by STDmaxV1-4 than STEMI criteria. Despite similar infarct size, TIMI flow, and coronary interventions, patients with STEMI(-) OMI and STDmaxV1-4 were less likely than STEMI(+) patients to undergo catheterization within 90 minutes (46% versus 68%; P=0.028). Conclusions Among patients with high-risk acute coronary syndrome, the specificity of ischemic STDmaxV1-4 was 97% for OMI and 96% for OMI requiring emergent percutaneous coronary intervention. STEMI criteria missed half of OMIs detected by STDmaxV1-4. Ischemic STDmaxV1-V4 in acute coronary syndrome should be considered OMI until proven otherwise.

Significance of 'recovery ST-segment depression' in exercise stress test.

OBJECTIVE: To study the significance of ST-segment depression during 'recovery' compared to that 'during stress' and 'both the phases' in exercise stress test. METHODS: Patients with positive exercise stress test who underwent coronary angiography (CAG) from 1st January 2017 to 31st December 2018 were studied. Patients were divided into 3 groups- Group A with ST-depression restricted to recovery phase, group B with ST-depression restricted to stress phase and group C with ST-depression seen both during exercise and recovery. All patients underwent CAG. Sensitivity, specificity, and predictive values of each of these groups in diagnosis of significant coronary artery disease (CAD) were analysed and compared. RESULTS: Total 300 patients were studied. Mean age of the study population was 48.77 ± 7.94 years. 78.3% of patients with positive exercise stress test had significant CAD. 96% of patients in group A had significant CAD, which was higher than in group B (88.9%) & group C (70.1%). The specificity, positive predictive value and negative predictive value of ST-segment depression in group A (96.92%, 96% and 25.2% respectively) were higher than that of ST-depression in group B (89.23%, 88.89% and 24.47% respectively) and group C (13.85%, 70.05% and 7.96% respectively). Sensitivity and accuracy of ST-depression in group A were lower (20.43% and 37% respectively), compared to other 2 groups. CONCLUSION: Patient with ST-depression restricted to recovery phase had highest specificity, positive predictive value, and negative predictive value. However, accuracy was highest in group with both stress phase and exercise ST-segment depression.

Electrocardiographic Recognition of Unprotected Left Main ST-Segment Elevation Myocardial Infarction: Looking Beyond aVR.

ST-segment elevation in aVR has traditionally been used for electrocardiographic identification of left main coronary artery (LM) myocardial infarction. We present two ST-segment elevation myocardial infarction (STEMI) cases with acute total occlusion of the LM without aVR ST-segment elevation. This report reviews the different electrocardiographic discriminators suggestive of unprotected LM STEMI. (Level of Difficulty: Intermediate.).

Accuracy of OMI ECG findings versus STEMI criteria for diagnosis of acute coronary occlusion myocardial infarction.

OBJECTIVE: In the STEMI paradigm of Acute Myocardial Infarction (AMI), many NSTEMI patients have unrecognized acute coronary occlusion MI (OMI), may not receive emergent reperfusion, and have higher mortality than NSTEMI patients without occlusion. We have proposed a new OMI vs. Non-Occlusion MI (NOMI) paradigm shift. We sought to compare the diagnostic accuracy of OMI ECG findings vs. formal STEMI criteria for the diagnosis of OMI. We hypothesized that blinded interpretation for predefined OMI ECG findings would be more accurate than STEMI criteria for the diagnosis of OMI. METHODS: We performed a retrospective case-control study of patients with suspected acute coronary syndrome. The primary definition of OMI was either 1) acute TIMI 0-2 flow culprit or 2) TIMI 3 flow culprit with peak troponin T ≥ 1.0 ng/mL or I ≥ 10.0 ng/mL. RESULTS: 808 patients were included, of whom 49% had AMI (33% OMI; 16% NOMI). Sensitivity, specificity, and accuracy of STEMI criteria vs Interpreter 1 using OMI ECG findings among 808 patients were 41% vs 86%, 94% vs 91%, and 77% vs 89%, and for Interpreter 2 among 250 patients were 36% vs 80%, 91% vs 92%, and 76% vs 89%. STEMI(-) OMI patients had similar infarct size and mortality as STEMI(+) OMI patients, but greater delays to angiography. CONCLUSIONS: Blinded interpretation using predefined OMI ECG findings was superior to STEMI criteria for the ECG diagnosis of Occlusion MI. These data support further investigation into the OMI vs. NOMI paradigm and suggest that STEMI(-) OMI patients could be identified rapidly and noninvasively for emergent reperfusion using more accurate ECG interpretation.