Low diagnostic yield of ST elevation myocardial infarction amplitude criteria in chest pain patients at the emergency department.

OBJECTIVES: To evaluate the diagnostic yield of the ECG criteria for ST-elevation myocardial infarction in a large cohort of emergency department chest pain patients, and to determine whether extended ECG criteria or reciprocal ST depression can improve accuracy. Design: Observational, register-based diagnostic study on the accuracy of ECG criteria for ST-elevation myocardial infarction. Between Jan 2010 and Dec 2014 all patients aged ≥30 years with chest pain who had an ECG recorded within 4 h at two emergency departments in Sweden were included. Exclusion criteria were: ECG with poor technical quality; QRS duration ≥120 ms; ECG signs of left ventricular hypertrophy; or previous coronary artery bypass surgery. Conventional and extended ECG criteria were applied to all patients. The main outcome was acute myocardial infarction (AMI) and an occluded/near-occluded coronary artery at angiography. Results: Finally, 19932 patients were included. Conventional ECG criteria for ST elevation myocardial infarction were fulfilled in 502 patients, and extended criteria in 1249 patients. Sensitivity for conventional ECG criteria in diagnosing AMI with coronary occlusion/near-occlusion was 17%, specificity 98% and positive predictive value 12%. Corresponding data for extended ECG criteria were 30%, 94% and 8%. When reciprocal ST depression was added to the criteria, the positive predictive value rose to 24% for the conventional and 23% for the extended criteria. Conclusions: In unselected chest pain patients at the emergency department, the diagnostic yield of both conventional and extended ECG criteria for ST-elevation myocardial infarction is low. The PPV can be increased by also considering reciprocal ST depression.

Electrocardiographic changes in the differentiation of ischemic and non-ischemic ST elevation.

Objectives. Pericarditis, takotsubo cardiomyopathy and early repolarization syndrome (ERS) are well-known to mimic ST elevation myocardial infarction (STEMI). We aimed to study whether ECG findings of reciprocal ST depression, PR depression, ST-segment convexity or terminal QRS distortion can discriminate between ST elevation due to ischemia and non-ischemic conditions. Design. Eighty-five patients with STEMI and 94 patients with non-ischemic ST elevation were included. All patients had acute chest pain and at least 0.1 mV ST elevation. Presence of PR depression, ST-segment convexity, terminal QRS distortion or reciprocal ST depression was assessed in each ECG. Results. In anterior ST elevation, ST depression in lead II (≥0.025 mV) occurred in 40% of patients with STEMI but in none of the non-ischemic cases. In inferior ST elevation, ST depression in lead I (≥0.025 mV) was present in 83% of patients with STEMI but in none of the non-ischemic cases. Chest-lead PR depression was uncommon in STEMI (12%) compared to non-ischemic cases (38%; p < .001). Convex ST elevation occurred in 22% of STEMI cases and in 9% of non-ischemic cases (p = .01). Terminal QRS distortion was more prevalent in STEMI (40%) than in non-ischemic ST elevation (7%). In multivariable analysis, reciprocal ST depression was associated with an ischemic diagnosis, whereas ST depression in aVR and chest-lead PR depression were associated with a non-ischemic diagnosis. Conclusions. Identification of true STEMI among patients with different ST-elevation etiology may be improved by considering reciprocal ST depression, ST depression in aVR and chest-lead PR depression.

Pheochromocytoma - An ECG diagnosis?

Pheochromocytoma is a rare catecholamine-secreting tumor in the adrenal medulla. In some cases, the first symptoms are cardiovascular. We report on two patients with pheochromocytoma, who both presented with bidirectional ventricular tachycardia (BDVT). We elaborate on the mechanisms of BDVT in the setting of pheochromocytoma.

Erroneous computer-based interpretations of atrial fibrillation and atrial flutter in a Swedish primary health care setting.

Objective: To describe the incidence of incorrect computerized ECG interpretations of atrial fibrillation or atrial flutter in a Swedish primary care population, the rate of correction of computer misinterpretations, and the consequences of misdiagnosis.Design: Retrospective expert re-analysis of ECGs with a computer-suggested diagnosis of atrial fibrillation or atrial flutter.Setting: Primary health care in Region Kronoberg, Sweden.Subjects: All adult patients who had an ECG recorded between January 2016 and June 2016 with a computer statement including the words 'atrial fibrillation' or 'atrial flutter'.Main outcome measures: Number of incorrect computer interpretations of atrial fibrillation or atrial flutter; rate of correction by the interpreting primary care physician; consequences of misdiagnosis of atrial fibrillation or atrial flutter.Results: Among 988 ECGs with a computer diagnosis of atrial fibrillation or atrial flutter, 89 (9.0%) were incorrect, among which 36 were not corrected by the interpreting physician. In 12 cases, misdiagnosed atrial fibrillation/flutter led to inappropriate treatment with anticoagulant therapy. A larger proportion of atrial flutters, 27 out of 80 (34%), than atrial fibrillations, 62 out of 908 (7%), were incorrectly diagnosed by the computer.Conclusions: Among ECGs with a computer-based diagnosis of atrial fibrillation or atrial flutter, the diagnosis was incorrect in almost 10%. In almost half of the cases, the misdiagnosis was not corrected by the overreading primary-care physician. Twelve patients received inappropriate anticoagulant treatment as a result of misdiagnosis.Key pointsData regarding the incidence of misdiagnosed atrial fibrillation or atrial flutter in primary care are lacking. In a Swedish primary care setting, computer-based ECG interpretations of atrial fibrillation or atrial flutter were incorrect in 89 of 988 (9.0%) consecutive cases.Incorrect computer diagnoses of atrial fibrillation or atrial flutter were not corrected by the primary-care physician in 47% of cases.In 12 of the cases with an incorrect computer rhythm diagnosis, misdiagnosed atrial fibrillation or flutter led to inappropriate treatment with anticoagulant therapy.

Bigeminal sandwiches galore.

A long run of PVCs "sandwiched" in between the sinus beats resulting in an almost doubling of the heart rate-interpolated PVCs in bigeminy-is described. This case illustrates three interesting aspects of interpolated PVCs. Although they are not uncommon, long runs of interpolated PVCs in bigeminy are rare findings. In this case, the arrhythmia had a duration of 3 minutes. Second, it illustrates the "age-old wisdom" of partial retrograde conduction. Also, even though the arrhythmia resulted in an almost doubling of the heart rate, the patient remained asymptomatic.

Chest-lead ST-J amplitudes using arm electrodes as reference instead of the Wilson central terminal in smartphone ECG applications: Influence on ST-elevation myocardial infarction criteria fulfillment.

BACKGROUND: "Smartphone 12-lead ECG" for the assessment of acute myocardial ischemia has recently been introduced. In the smartphone 12-lead ECG either the right or the left arm can be used as reference for the chest electrodes instead of the Wilson central terminal. These leads are labeled "CR leads" or "CL leads." We aimed to compare chest-lead ST-J amplitudes, using either CR or CL leads, to those present in the conventional 12-lead ECG, and to determine sensitivity and specificity for the diagnosis of STEMI for CR and CL leads. METHODS: Five hundred patients (74 patients with ST elevation myocardial infarction (STEMI), 66 patients with nonischemic ST deviation and 360 controls) were included. Smartphone 12-lead ECG chest-lead ST-J amplitudes were calculated for both CR and CL leads. RESULTS: ST-J amplitudes were 9.1 ± 29 µV larger for CR leads and 7.7 ± 42 µV larger for CL leads than for conventional chest leads (V leads). Sensitivity and specificity were 94% and 95% for CR leads and 81% and 97% for CL leads when fulfillment of STEMI criteria in V leads was used as reference. In ischemic patients who met STEMI criteria in V leads, but not in limb leads, STEMI criteria were met with CR or CL leads in 91%. CONCLUSION: By the use of CR or CL leads, smartphone 12-lead ECG results in slightly lower sensitivity in STEMI detection. Therefore, the adjustment of STEMI criteria may be needed before application in clinical practice.

Criteria for ECG detection of acute myocardial ischemia: Sensitivity versus specificity.

BACKGROUND: Criteria for electrocardiographic detection of acute myocardial ischemia recommended by the Consensus Document of ESC/ACCF/AHA/WHF consist of two parts: The ST elevation myocardial infarction (STEMI) criteria based on ST elevation (ST↑) in 10 pairs of contiguous leads and the other on ST depression (ST↓) in the same 10 contiguous pairs. Our aim was to assess sensitivity (SE) and specificity (SP) of these criteria-and to seek their possible improvements-in three databases of 12­lead ECGs. METHODS: We used (1) STAFF III data of controlled ischemic episodes recorded from 99 patients (pts) during percutaneous coronary intervention (PCI) involving either left anterior descending (LAD) coronary artery, right coronary artery (RCA), or left circumflex (LCx) coronary artery. (2) Data from the University of Glasgow for 58 pts with acute myocardial infarction (AMI) and 58 pts without AMI, as confirmed by MRI. (3) Data from Lund University retrieved from a centralized ECG management system for 100 pts with various pathological ST changes-other than acute coronary occlusion-including ventricular pre-excitation, acute pericarditis, early repolarization syndrome, left ventricular hypertrophy, and left bundle branch block. ST measurements at J-point in ECGs of all 315 pts were obtained automatically on the averaged beat with manual review and the recommended criteria as well as their proposed modifications, were applied. Performance measures included SE, SP, positive predictive value (PPV), and benefit-to-harm ratio (BHR), defined as the ratio of true-positive vs. false-positive detections. RESULTS: We found that the SE of widely-used STEMI criteria can be indeed improved by the additional ST↓ criteria, but at the cost of markedly decreased SP. In contrast, using ST↑ in only 3 additional contiguous pairs of leads (STEMI13) can boost SE without any loss of SP. In the STAFF III database, SE/SP/PPV were 56/98/97% for the STEMI, 79/79/79% for the STEMI with added ST↓ and 67/97/96% for the STEMI13. In the Glasgow database, corresponding SE/SP/PPV were 43/98/96%, 84/90/89%, and 55/98/97%. For the Lund database, SP was 56% for the STEMI, 24% for the STEMI with ST↓, and 56% for the STEMI13. CONCLUSION: Current recommended criteria for detecting acute myocardial ischemia, involving ST↓, boost SE of widely-used STEMI criteria, at the cost of SP. To keep the SP high, we propose either the adjustment of threshold for the added ST↓ criteria or a selective use of ST↓ only in contiguous leads V2 and V3 plus ST↑ in lead pairs (aVL, -III) and (III, -aVL).

Galen Wagner, M.D., Ph.D. (1939-2016) as international mentor of young investigators in electrocardiology.

This paper describes a substantial part of the international mentoring network of students and young investigators in electrocardiology that developed around Dr. Galen Wagner (1939-2016), including many experiences of his mentees and co-mentors. The paper is meant to stimulate thinking about international mentoring as a means to achieve important learning experiences and personal development of young investigators, to intensify international scientific cooperation, and to stimulate scientific production.

The Olson method for detection of acute myocardial ischemia in patients with coronary occlusion.

An automated ECG-based method may provide diagnostic support in the management of patients with acute coronary syndrome. The Olson method has previously proved to accurately identify the culprit artery in patients with acute coronary occlusion. METHODS: The Olson method was applied to 360 patients without acute myocardial ischemia and 52 patients with acute coronary occlusion. RESULTS: This study establishes the normal variation of the Olson wall scores in patients without acute myocardial ischemia, which provides the basis for implementation of the Olson method for triage of patients with acute coronary syndrome. All patients with acute occlusion had Olson wall scores above the upper limit of normal. CONCLUSION: The Olson method can be used for ischemia detection with very high sensitivity. Future studies are needed to explore specificity in patients with non-ischemic ST elevation.

A patient with non-ST-segment elevation acute coronary syndrome: Is it possible to predict the culprit coronary artery?

In acute coronary syndromes without ST-segment elevation (NSTE-ACS), identification of the culprit artery is, most often, not possible. In this case report, we elaborate on the likelihood of different culprit arteries in a patient with NSTE-ACS. While her symptoms were progressing, typical ECG findings of ischemia in the left coronary territories were diminishing. Instead, dynamic T-wave changes in the inferior leads were present and were most likely postischemic and "reischemic." Although the culprit artery could not be identified with certainty by means of these subtle changes, they correlated well with the findings on angiography and the ECG recorded afterward. This case report demonstrates the importance of analyzing ECG and its temporal changes in conjunction with evolving symptoms.

Scientific STAFF and MALT meetings - past, present, and future.

The scientific STAFF and MALT meetings were created around the turn of the century for scientists engaged in enhancing the role of the 12-lead ECG for detection and quantification of involved myocardium in patients with acute coronary syndrome. These meetings were initially focused on computer processing of data from two single-center databases. The STAFF database was collected in the mid-nineties on patients with prolonged total coronary occlusion; high-resolution 12-lead ECGs were collected before, during, and after 5 minutes of occlusion. The MALT database was created in the early years of this century on consecutive patients with chest pain admitted to a large teaching hospital. Delayed enhancement magnetic resonance imaging and electrocardiograms were recorded in these acutely ill patients. The paper highlights the first 2 decades of the STAFF and MALT meetings and details the meeting format.

A 12-lead ECG-method for quantifying ischemia-induced QRS prolongation to estimate the severity of the acute myocardial event.

INTRODUCTION: Studies have shown terminal QRS distortion and resultant QRS prolongation during ischemia to be a sign of low cardiac protection and thus a faster rate of myocardial cell death. A recent study introduced a single lead method to quantify the severity of ischemia by estimating QRS prolongation. This paper introduces a 12-lead method that, in contrast to the previous method, does not require access to a prior ECG. METHODS: QRS duration was estimated in the lead that showed the maximal ST deviation according to a novel method. The degree of prolongation was determined by subtracting the measured QRS duration in the lead that showed the least ST deviation. RESULTS: The method is demonstrated in examples of acute occlusion in two of the major coronary arteries. CONCLUSION: This paper presents a 12-lead method to quantify the severity of ischemia, by measuring QRS prolongation, without requiring comparison with a previous ECG.

Validation of the vessel-specific leads (VSLs) for detection of acute ischemia on a dataset with non-ischemic ST-segment deviation.

BACKGROUND: Existing criteria recommended by ACC/ESC for identifying patients with ST elevation myocardial infarction (STEMI) from the 12-lead ECG perform with high specificity (SP) but low sensitivity (SE). In our previous studies, we found that the SE of acute ischemia detection can be markedly improved without any loss of SP by calculating, from the 12-lead ECG, ST deviation in 3 "optimal" vessel-specific leads (VSLs). To further validate the method, we evaluated the SP performance using a dataset with non-ischemic ST-segment changes. METHODS: 12-lead ECGs of 100 patients (75 males/25 females, age range 12-83years, average age 52years) were retrieved from a centralized ECG management system at Skåne University Hospital, Lund, Sweden. These ECGs were chosen to represent five subgroups with various causes of pathological ST deviation, other than acute coronary occlusion: a) ventricular preexcitation (n=12), b) acute pericarditis (n=26), c) early repolarization syndrome (ERS) (n=14), d) left ventricular hypertrophy (LVH) with "strain" (n=26), and e) left bundle branch block (LBBB) (n=22). ECGs with inadequate signal quality, heart rate exceeding 120bpm and/or atrial flutter were not selected for this study population. Both STEMI criteria and VSLs criteria with and without a new augmented LVH-specific derived lead were tested. SP, calculated for each subgroup and combined, was used as the performance measure for comparison. RESULTS: SP test results for the STEMI criteria vs. the VSLs method without the augmented LVH lead were 100% vs. 92%, 4% vs. 88%, 29% vs. 100%, 100% vs. 77%, and 64% vs. 68% for the five subgroups with preexcitation, pericarditis, ERS, LVH, and LBBB, respectively. For the whole group, SP was 57% for the STEMI criteria and 83% for the VSLs criteria; this improvement was statistically significant (p<0.001). With the augmented LVH lead, SP for the VSLs improved from 77% to 96% for the LVH subgroup and SP for the other subgroups remained unchanged. For the whole study group, SP improved from 83% to 88%. CONCLUSION: Based on these results, we conclude that the VSLs criteria are not only more sensitive in detecting acute ischemia but also more specific in recognizing patients with non-ischemic ST deviation than the existing STEMI criteria. This finding needs to be further corroborated on a larger patient population with AMI prevalence typical of the population presenting to the emergency room.

Ischemic QRS prolongation as a biomarker of severe myocardial ischemia.

BACKGROUND: Previous studies have shown that QRS prolongation is a sign of depressed collateral flow and increased rate of myocardial cell death during coronary occlusion. The aims of this study were to evaluate ischemic QRS prolongation as a biomarker of severe ischemia by establishing the relationship between prolongation and collateral flow experimentally in a dog model, and test if the same pattern of ischemic QRS prolongation occurs in man. METHODS: Degree of ischemic QRS prolongation was measured using a novel method in dogs (n=23) and patients (n=52) during coronary occlusion for 5min. Collateral arterial flow was assessed in the dogs. RESULTS: There was a significant correlation between QRS prolongation and collateral flow in dogs (r=0.61, p=0.008). Magnitude and temporal evolution of prolongation during ischemia were similar for dogs and humans (p=0.202 and p=0.911). CONCLUSION: Quantification of ischemic QRS prolongation could potentially be used as a biomarker for severe myocardial ischemia.

The classical versus the Cabrera presentation system for resting electrocardiography: Impact on recognition and understanding of clinically important electrocardiographic changes.

The classical system for presentation of the 12-lead electrocardiogram (ECG) reflects the electrical activity of the heart as viewed in the transverse plane by 6 leads with a single anatomically ordered sequence, V1-V6; but in the frontal plane by 6 leads with dual sequences, I, II, and III, and aVR, aVL, and aVF. However, there is also a single anatomically ordered sequence of leads, called the Cabrera display that presents the six frontal plane leads in their anatomically ordered sequence of: aVL, I, -aVR, II, aVF, and III. Although it has been recognized that the Cabrera system has clinical diagnostic advantages compared to the classical display, it is currently only used in Sweden. The primary explanation of why the Cabrera system has not been adopted internationally has been that analog ECG recorders had technical limitations. Currently, however, the classical system is most often seen as a historical remnant that prevails because of conservatism within the cardiology community.

Comparison of model-based and expert-rule based electrocardiographic identification of the culprit artery in patients with acute coronary syndrome.

BACKGROUND AND PURPOSE: Culprit coronary artery assessment in the triage ECG of patients with suspected acute coronary syndrome (ACS) is relevant a priori knowledge preceding percutaneous coronary intervention (PCI). We compared a model-based automated method (Olson method) with an expert-rule based method for the culprit artery assessment. METHODS: In each of the 53 patients who were admitted with the working diagnosis of suspected ACS, scheduled for emergent angiography with a view on revascularization as initial treatment and subsequently found to have an angiographically documented completely occluded culprit artery, culprit artery location was assessed in the preceding ECG by both the model-based Olson method and the expert-rule based method that considered either visual or computer-measured J-point amplitudes. ECG culprit artery estimations were compared with the angiographic culprit lesion locations. Proportions of correct classifications were compared by a Z test at the 5% significance level. RESULTS: The Olson method performed slightly, but not significantly, better, when the expert-rule based method used visual assessment of J-point amplitudes (88.7% versus 81.1% correct; P=0.28). However, the Olson method performed significantly better when the expert-rule based method used computer-measured J-point amplitudes (88.7% versus 71.7% correct; P<0.05). CONCLUSION: The automated model-based Olson method performed at least at the level of expert cardiologists using a manual rule-based method.

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

The electrocardiogram (ECG) is the most widely used imaging tool helping in diagnosis and initial management of patients presenting with symptoms compatible with acute coronary syndrome. Acute ischemia affects the configuration of the QRS complexes, the ST segments and the T waves. The ECG should be read along with the clinical assessment of the patient. ST segment elevation (and ST depression in leads V1 -V3 ) in patients with active symptoms usually indicates acute occlusion of an epicardial artery with ongoing transmural ischemia. These patients should be triaged for emergent reperfusion therapy per current guidelines. However, many patients have ST segment elevation secondary to nonischemic causes. ST depression in leads other than V1 -V3 usually are indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries or spasm supply/demand mismatch. ST depression may also be secondary to nonischemic etiologies, such as left ventricular hypertrophy, cardiomyopathies, etc. Knowing the clinical scenario, comparison to previous ECG and subsequent ECGs (in cases that there are changes in the quality or severity of symptoms) may add in the diagnosis and interpretation in difficult cases. This review addresses the different ECG patterns, typically seen in patients with active symptoms, after resolution of symptoms and the significance of such changes when seen in asymptomatic patients.