Significance of signal-averaged P-wave changes during exercise in patients with coronary artery disease and correlation with angiographic findings.

The maximal P-wave duration in all time-aligned leads, and the maximal P-wave amplitude in leads V5 and V6 were measured on a 12-lead, signal-averaged electrocardiogram during the recovery period of an exercise stress test (EST). The study group consisted of 75 patients with coronary artery disease (CAD) documented by greater than or equal to 50% diameter stenosis in 1 or more arteries and a control group of 47 subjects, 15 of them young volunteers and 32 with no or minimal coronary atherosclerosis and normal left ventricular function. All subjects underwent a symptom limited EST, with use of the Ellestad protocol. Signal-averaged P waves recorded before exercise, and for the first 6 minutes in recovery were measured using a 5x magnifier. The mean P duration before exercise in the control group was 107 +/- 16 ms (+/- 1 standard deviation) and 111 +/- 15 ms at the third minute of recovery, (p less than 0.001). In patients with CAD it was 112 +/- 12 and 129 +/- 19 ms (+/- 1 standard deviation), p less than 0.001, respectively. Differences in P-wave duration were found to be statistically significant (p less than 0.001) throughout recovery in the group with CAD when compared with control and maximal values at the third minute. The increase in P-wave duration (greater than or equal to 20 ms) was used as an additional parameter to exercise-induced ST-segment depression, ST elevation, or anginal pain for the test interpretation. The sensitivity increased from 57 to 75% and the specificity decreased from 85 to 77%.(ABSTRACT TRUNCATED AT 250 WORDS)