A novel method for the detection of transient myocardial ischaemia using body surface electrocardiac mapping

Optimal ECG Lead System for Exercise Assessment of Ischemic Heart Disease

The diagnostic value of an ECG exercise test in diagnosis of ischemic heart disease (IHD) is limited. We investigated whether it is possible to develop a method for diagnosis of IHD which uses a low number of optimal ECG leads and has a higher diagnostic efficiency than conventional exercise ECG. This study was carried out on 43 patients. The 67-lead high-resolution ECG was recorded at rest and during exercise. The diagnostic value of ST segment depression (ΔST60) and T-wave morphology change (δT) determined in optimized ECG lead configurations was higher than for the standard 12-lead ECG. The best results were obtained for δT determined from 6 ECG electrode locations where sensitivity and specificity were 70% and 69% whereas for the standard exercise ECG were 63% and 62%, respectively. The small number of ECG leads used allows for easy hardware implementation of the methods for use in clinical settings.

Myocardial ischaemia in patients with coronary endothelial dysfunction: insights from body surface ECG mapping and implications for invasive evaluation of chronic chest pain

AIMS

Coronary endothelial dysfunction (ED), by predisposing to abnormal vasomotion, may cause chest pain in individuals with non-obstructed coronary arteries. The aim of this study was to correlate the magnitude of coronary ED with the presence and extent of inducible myocardial ischaemia using body surface electrocardiogram (ECG) mapping in symptomatic patients.

METHODS AND RESULTS

In 30 patients with chest pain and angiographically normal coronary arteries or mild atherosclerosis, we studied endothelium-dependent responses with acetylcholine (ACH) and endothelium-independent function with nitroglycerin and adenosine in the left anterior descending artery. Eighty-lead body surface ECG maps were collected at baseline and after each dose of ACH. There was a significant correlation between the maximal change in epicardial diameter with ACH and the magnitude of ST-segment shift [r = -0.44 (95% CI: -0.097 to -0.69), P = 0.015]. Patients with ≥ 0.05 mV ST-segment shift/lead had greater epicardial vasoconstriction (31.6 vs. 15.6%, P = 0.019), and lower coronary flow reserve (2.9 vs. 3.6, P = 0.047) compared with those with ST-segment shift <0.05 mV. Four patients had inducible ischaemia with ACH in the absence of abnormal epicardial or global microvascular vasomotion (>20% decrease in diameter or <50% increase in blood flow).

CONCLUSIONS

This study demonstrates that abnormal vasomotion due to coronary ED is associated with myocardial ischaemia in patients with chest pain. The magnitude of ischaemia correlates with the extent of ED. A small subset of patients develop myocardial ischaemia during ACH infusion without significant abnormalities in epicardial or global microvascular endothelium-dependent blood flow responses.

Electrocardiographic body surface mapping: potential tool for the detection of transient myocardial ischemia in the 21st century?

Coronary artery disease (CAD) is one of the leading causes of cardiovascular mortality and morbidity worldwide. CAD presents as a wide spectrum of clinical disease from stable angina to ST segment elevation myocardial infarction. The 12-lead electrocardiogram (ECG) has been the main tool for the diagnosis of these events for almost a century but is limited in its diagnostic ability. For patients with suspected angina, the exercise tolerance test is often used to provoke and detect stress-induced ischemia but does not provide a definitive answer in a substantial proportion of patients. Body surface mapping (BSM) is a technique that samples multiple points around the thorax to provide a more comprehensive electrocardiographic data set than the conventional 12-lead ECG. Moreover, recent preliminary data demonstrate that BSM can detect and display transient regional myocardial ischemia in an intuitive fashion, employing subtraction color mapping, making it potentially valuable for diagnosing CAD causing transient regional ischemia. Research is ongoing to determine the full extent of its utility.

Estimated body surface potential maps in emergency department patients with unrecognized transient myocardial ischemia

BACKGROUND

We report on 5 patients who presented to the emergency department (ED) with chest pain, had negative serum troponin levels, and were discharged with a presumed noncardiac diagnosis. Thereafter, retrospective analysis of Holter monitoring data recorded for a clinical trial revealed ST events indicative of transient myocardial ischemia that was unrecognized clinically.

STUDY AIM

The purpose of this analysis was to determine whether initial body surface potential maps estimated from optimal ischemia electrode sites estimated body surface potential map (EBSPM) showed signs of ischemia in the missed ischemia group that could have prevented misdiagnosis.

METHODS

This is a secondary analysis of data from a prospective clinical trial in which patients were attached to 2 Holter monitor devices for simultaneous recordings. One Holter device recorded a standard Mason-Likar 12-lead electrocardiogram (ECG) and the other recorded a 10-electrode lead set considered optimal for ischemia detection. A body surface potential map was then estimated from the optimal lead set.

RESULTS

At 1 year, 2 of the 5 patients with missed ischemia died and a third had an acute myocardial infarction (MI) (40% mortality, 60% death/nonfatal MI). In comparison, 1-year mortality was 5.7% in 159 similar patients treated for unstable angina at the same institution over the same period (P = .037). The initial standard ECG showed no abnormalities in 3 patients and showed left ventricular hypertrophy in 1. The fifth patient with a history of recent MI had slight ST elevation in leads III and aVF and Q waves that were considered indicative of recent (not acute) MI. EBSPM data recorded at the time of ED presentation matched the standard ECG (normal in 3, left ventricular hypertrophy or inconclusive in 2). During transient ischemia, all 5 EBSPMs showed areas of ischemia overlapping with standard electrode sites.

CONCLUSION

Patients evaluated in the ED for chest pain are at high risk for death or nonfatal MI if they have ischemic events with continuous ST-segment monitoring that are unrecognized clinically. In this small cohort with unrecognized ischemia, the initial body surface potential maps estimated from optimal ischemia electrode sites did not improve on 12-lead ST-segment monitoring to identify this high-risk group.

Electrocardiographic predictors of cardiovascular outcome in women: the National Heart, Lung, and Blood Institute-sponsored Women's Ischemia Syndrome Evaluation (WISE) study

OBJECTIVES

We sought to analyze the value of infrequently measured parameters of the 12-lead electrocardiogram (ECG) in predicting cardiovascular events in women with suspected myocardial ischemia who were referred for cardiac catheterization.

BACKGROUND

Routinely analyzed ECG parameters have low predictive value for cardiovascular events in women with preserved left ventricular function and suspected myocardial ischemia. The predictive value of ECG parameters for cardiovascular disease has not been fully determined.

METHODS

Women enrolled in the National Heart, Lung, and Blood Institute-sponsored Women's Ischemia Syndrome Evaluation (WISE) study who had complete digital 12-lead ECG and quantitative angiography data were studied. Clinical and ECG predictors of cardiovascular disease events, defined as death, congestive heart failure, and non-fatal myocardial infarction, were determined.

RESULTS

Of 143 women with ECG and angiographic data (mean age 59 +/- 13 years, left ventricular ejection fraction 64.1 +/- 8.6%), 13% had events during a mean follow-up period of 3.3 +/- 1.6 years. Independent predictors of event occurrences included a wider QRS-T angle (i.e., the spatial electrical angle between the QRS complex and the T-wave; p = 0.0005), wider QRS complex (p = 0.004), longer QTrr (i.e., age- and gender-adjusted QT interval; p = 0.0004), a more depressed ST-segment in precordial lead V5 (p = 0.0002), and a higher coronary artery disease severity score (p = 0.02).

CONCLUSIONS

Several 12-lead ECG parameters, such as the QRS-T angle and the QRS and QTrr duration, are predictive of future cardiovascular events in women with suspected myocardial ischemia.