The predictive value of exercise QRS duration changes for post-PTCA coronary events

Abstract

Background: The sensitivity and predictive values of exercise ECG testing using ST-T criteria after percutaneous transluminal coronary angioplasty (PTCA) are low, precluding its routine use for screening for restenosis. The predictive value of QRS duration criteria during exercise testing (ET) ECG after PTCA for future coronary events has not been reported. The aim of the study was to compare QRS duration changes with ST-T criteria during ET, as a predictor of coronary events after PTCA.

Methods: A prospective study of 206 consecutive patients who underwent ET at a mean of 34 +/- 14 days after their first PTCA, and were the followed for a mean of 23 +/- 9 months. Patients were divided by QRS duration into two groups-Q1: ischemic response (QRS duration prolongation of more than 3 ms relative to the resting duration), and Q2: normal response (QRS duration shortening or without change from resting duration). Patients were also divided by their ST-T response, S1: ischemic response, and S2: normal response.

Results: During follow-up 52 patients (58%) experienced restenosis or MI, or underwent CABG-Q1: 44 (85%), Q2: 8(15%) (P < 0.0002), S1: 8 (15%), S2: 44 (85%), (P < 0.641), two patients died-Q1: 1 (1%) and Q2: 1 (1%). For QRS and ST-T, the relative risk of having at least one of the coronary events was 4.02 (CI 2.1-9.9) versus 1.13 (CI 0.8-2.9), respectively. The sensitivity for future coronary events was 85% and 52% and the specificity was 48% and 98% for the QRS and ST-T criteria, respectively.

Conclusion: QRS prolongation during peak ET ECG after PTCA is a more sensitive marker than ST-T criteria for detection of patients at risk for later coronary events.

Figure 1

Measurement of QRS duration interval.

Figure 2

Histogram depicting QRS duration changes in the entire study population.

Figure 3

Percent of patients with no cardiac event (restenosis, CABG, and MI) during follow‐up in the QRS duration groups. The dotted lines represent patients with ischemic QRS response. The solid line represents patients with nonischemic QRS response.

Figure 4

Percent of patients with no cardiac event (restenosis, CABG, and MI) during follow‐up in the ST‐T criteria groups. The dotted lines represent patients with ischemic ST‐T response. The solid line represents patients with nonischemic ST‐T response.

Figure 5

Relative risk for coronary events relative to an ischemic QRS or ischemic ST‐T response. MI = myocardial infarction, CABG = coronary artery bypass grafting, CE = coronary event (restenosis, MI or CABG).

Figure 6

Predictive value of the test. Sensitivity and specificity using the ischemic criteria for ST‐T changes, QRS changes, or combination of the two criteria: Patients with both ischemic responses and patients with at least one ischemic response.