Efficacy of anti-anginal drugs in the treatment of angina pectoris associated with silent myocardial ischemia: importance of quantitative Holter ECG data for patient activity.

Methods: We evaluated the clinical efficacy of transdermal nitroglycerin (NTG-TTS), a patch application of a nitrate, in the treatment of 27 patients with angina pectoris who had asymptomatic myocardial ischemic (SMI) attacks, using a double-blind cross-over method. Evaluation was made using Holter ECG and patient activity data.

Results: In frequency and duration of continuation of SMI episodes, no significant differences were noted between the observation and placebo treatment periods, while the values of both these parameters were decreased significantly in the active drug treatment period compared with those in the observation and placebo treatment periods. Critical heart rate, the heart rate at the initiation of ST-segment depression, was significantly higher during the period of active drug treatment than during the placebo treatment and observation periods. In SMI frequency index, which was determined by adjusting the SMI frequency for the number of steps taken, there were no significant differences between the 3 periods. The SMI time index was significantly lower in the active drug treatment period than in the observation period.

Conclusions: These results indicated that the clinical evaluation of the efficacy of anti-anginal drugs against SMI should take into consideration individual patient activity data.