Septal Q wave in exercise testing: evaluation by single-photon emission computed tomography.

Changes of septal Q waves in lead V5 by exercise were evaluated with single-photon emission computed tomography. Coronary artery disease was present in 66 patients, 48 of whom had left anterior descending coronary artery (LAD) involvement. Forty-one subjects had normal coronary arteries. All patients under investigation were classified into 3 groups: group A (18 patients)--regression of Q amplitude during exercise; group B (48 patients)--progression or no change of Q wave or a new Q wave during exercise; and group C (41 patients)--no Q waves at rest and during exercise. Perfusion defects of the septum were calculated 3-dimensionally and expressed as a percent of the total septum. Seventeen patients (94%) in group A showed septal perfusion defects by exercise and all of them had LAD stenosis. Forty-three patients (90%) in group B showed no septal perfusion defects, but the others with perfusion defects had LAD stenosis. In group C, 23 of 41 patients (56%) had an LAD lesion, of whom 91% showed septal perfusion defects; none of the remaining 18 patients without LAD stenosis showed perfusion defects. The area of septal perfusion defects during exercise was larger in group A (62 +/- 19%) and in group C (52 +/- 19%) than in group B (23 +/- 9%) (groups A vs B, p less than 0.001; groups C vs B, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)