[Variations in the amplitude of the Q wave at V5 during computerized exercise test. Value in the diagnosis of coronary insufficiency].

The aim of this study was to evaluate the diagnostic value of changes in Q wave amplitude in the V5 chest lead in coronary artery disease, especially for the detection of significant (greater than or equal to 75% narrowing) left interior descending disease. The stress tests of 227 patients were reviewed and confronted with the results of coronary angiography in 93 patients with angiographically normal arteries, and 134 patients with left anterior descending disease of the latter, 37 had single vessel disease, 38 had double vessel disease and 59, triple vessel disease. The average values of the Q wave amplitude in V5 at the peak of effort were 0.97 +/- 1.04 mm in the control group; 0.53 +/- 0.65 mm (p less than 0.01) in the group with single vessel disease; 0.46 +/- 0.66 mm (p less than 0.01) in the group with double vessel disease and 0.64 +/- 0.9 mm (p = 0.04) in the group with triple vessel disease. The mean variations of the amplitude of the Q wave in lead V5 on effort in the same group of patients were: +0.55 +/- 0.73 mm (p less than 0.001); + 0.11 +/- 0.66 mm (NS); + 0.02 +/- 0.5 mm (NS) and + 0.05 +/- 0.53 mm (NS), respectively. The Q wave in lead V5 was generally deeper on effort in the control group and the average variation in its amplitude was statistically significant only in this group. In the coronary patients, the Q wave in lead V5 was generally smaller and its amplitude did not change significantly on effort.(ABSTRACT TRUNCATED AT 250 WORDS)