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 < 0.001; groups C vs B, p < 0.01). Late imaging revealed small perfusion defects in group A (12 ±9 %) and group B (6 ± 8 %) and relatively large in group C (32 ± 24%) (groups A vs C, p < 0.01; groups B vs C, p < 0.05). In conclusion, single-photon emission computed tomography during exercise revealed that septal Q waves are valuable in assessing the degree of septal ischemia.