Evaluation of antianginal drug treatment by precordial exercise electrocardiography.

We tried to assess the efficacy of precordial exercise electrocardiography (PEE) in evaluating various antianginal drugs. PEE was performed by 18 precordial electrodes. Leads V2-V7 were recorded at their usual position and one intercostal space higher and lower. The Bruce treadmill exercise protocol was used. A positivity index (PI) was formulated as follows. The total sum of maximal ST-segment depression (sigma ST reduced) X 100 was divided by the product of the number of precordial leads X minutes of exercise duration: (Formula: see text). The PI was measured basally and after the administration of nitroglycerin (NTG) ointment, 7.5 mg (7 patients), propranolol (P) 20-40 mg, 3 times daily (7 patients) and nifedipine (N), 10 mg 3-4 times daily (7 patients). A significant decrease of the PI was seen with NTG (p less than 0.01) and P (p less than 0.05) but not with N. However, in the N group, 2 patients had a significant increase in heart frequency, with resultant exercise deterioration. The remaining 6 patients had a satisfactory response to the drug (p less than 0.05). The PI is useful in assessing the antianginal efficacy of various medications. From our study it is suggested that inordinate tachycardia may negate the beneficial effect of N in some patients.