Feasibility of Resting Multielectrode Electrocardiogram for Detecting Coronary Artery Disease

Abstract

Background: Myocardial ischemia can cause repolarization heterogeneity, manifesting as variations in QT interval; we hypothesized that repolarization heterogeneity could help identify patients with coronary artery disease (CAD). We tested this hypothesis by measuring repolarization heterogeneity with a newly developed multielectrode electrocardiogram (MECG) system, which uses 28 electrodes to increase the spatial resolution of body surface electrical activity.

Methods and results: Male patients admitted for coronary angiography were enrolled. Eighty-five patients were included in the training dataset, and 42 in the validation dataset. QTc heterogeneity indices including QTc dispersion (QTD) and smoothness index of QTc (SI-QTc) were derived from MECG signals. Sixty and 32 patients in the training and validation datasets, respectively, were found to have significant coronary stenosis. The SI-QTc (12.79 ± 4.29 vs. 9.22 ± 2.40 ms, p = 0.0004) and QTD (92.12 ± 34.31 vs. 67.2 ± 19.11 ms, p = 0.0004) of the patients in the training dataset were significantly higher in the CAD patients. The areas under the curve of SI-QTc and QTD in the training dataset were 0.7437 and 0.7433, respectively, for detecting CAD. With cutoff values of SI-QTc ≥ 9.95 ms and QTc dispersion ≥ 69 ms, the sensitivity and specificity for diagnosing CAD were 71.9% and 80.0%, respectively, in the validation dataset.

Conclusions: Resting MECG is a promising noninvasive tool for CAD diagnosis, with sensitivity and specificity comparable to those of the exercise electrocardiography test.

Keywords: Coronary artery disease; Multielectrode electrocardiogram; QTc heterogeneity.

Figure 1

The 24-electrode electrocardiography (ECG) patch and its spatial relation to the anatomical structure.

Figure 2

Flow diagram of electrocardiography (ECG) preprocessing and QTc interval calculation.

Figure 3

QTc contour map and QTc gradient map for the visual display of QTC heterogeneity. ECG, electrocardiography; SI-QTc, spatial smoothness index of QTc.

Figure 4

Example of multielectrode electrocardiogram (MECG) data and their correlation with coronary angiography. The Green asterisk indicates the onset of QRS wave; the blue asterisk, the termination of T wave. (A) A 59-year-old man with critical single-vessel disease (left circumflex artery with 90% stenosis). His spatial smoothness index of QTc (SI-QTc) and QTc dispersion (QTD) were 13.35 and 93 ms, respectively. (B) A 57-year-old man with patent coronary arteries. His SI-QTc and QTD were 9.40 and 49 ms, respectively.

Figure 5

Flow chart of patient enrollment. CAD, coronary artery disease; CABG, coronary artery bypass grafting; CAG, coronary angiography.

Figure 6

Receiver operating characteristic (ROC) curve analysis of QTc dispersion (QTD), smoothness index (SI-QTc) of multielectrode electrocardiogram (MECG), and QTc dispersion (QTd) of the precordial 12-lead electrocardiography (ECG). CI, confidence interval. AUC, area under the curve; CI, confidence interval.

Central Illustration

Resting multielectrode electrocardiogram (MECG) is a promising noninvasive tool for coronary artery disease (CAD) diagnosis, and its sensitivity and specificity were comparable to those of the exercise electrocardiography (ECG) test. CAG, coronary angiography; QTD, QTc dispersion; QTd, QT interval dispersion; ROC, receiver operating characteristic; SI-QTc, spatial smoothness index of QTc.

Supplementary Figure 1

Difference in QT interval in the body surface caused by three ischemic regions in the heart (left anterior descending [LAD], left circumflex [LCx], and right coronary artery [RCA]).

Supplementary Figure 2

QTc gradient map in patients with single-vessel coronary artery disease (CAD). (A) A 69-year-old man had positive results for the treadmill exercise test. Coronary angiography (CAG) revealed severe occlusion over the distal right coronary artery (RCA). The QT dispersion was 80 msec. (B) A 66-year-old man who had left anterior descending (LAD) stent implantation 3 years back was found to have reperfusion defect on myocardial perfusion scan. CAG revealed LAD in-stent restenosis with total occlusion. The QT dispersion was 103 msec.