Evaluation of exercise-induced Q-wave amplitude changes and their clinical value.

We studied the influence of exercise level, severity of coronary artery disease (CAD), presence of previous myocardial infarction (MI), anterior or diaphragmatic, on the clinical value of exertional Q wave changes (Delta-Q). We retrospectively evaluated the exercise electrocardiograms of 62 patients without angiographic evidence of CAD and 133 patients with CAD; 28 of them had single (SVD) and 105 multivessel disease (MVD). Forty-one patients had a previous diaphragmatic MI and 23 anterior. The sensitivity, specificity and predictive value of Delta-Q were compared to the ST criterion. The exercise level affected Delta-Q. ST and Delta-Q had similar specificity and predictive values. The extent of CAD did not affect the sensitivity of Delta-Q and this method was better than ST to detect SVD patients. The Delta-Q criterion was equally as efficient as ST in MVD patients without MI and with diaphragmatic MI. The loss of septal forces on resting electrocardiograms made useless Delta-Q analysis on patients with anterior MI. The improvement of sensitivity in SVD patients by Delta-Q might be of clinical value since these latter are frequently not diagnosed by the ST criterion.