Unstable angina. Effect of pravastatin on results of 24-hour ECG monitoring and exercise tests

We have assessed various effects of early use of pravastatin in acute unstable angina in an open randomized study. Data on changes of lipids, platelet aggregation and some parameters of hemostasis have been published previously. Here we report results of 24-hour ECG monitoring and exercise tests. Methods. Patients aged 35-65 years hospitalized due to unstable angina were randomized to open pravastatin (n=20, 40-80 mg/day for 90 days) or no pravastatin (n=19) within 24 hours after index attack of pain. Holter ECG monitoring was carried out on days 1 and 7, bicycle exercise tests - on days 14 and 90 after randomization. The following parameters of heart rate variability (HRV) were evaluated on 24-hour ECGs: total (0.003-0.40 Hz), very low (VLF; 0.003-0.04 Hz), low (0.04-0.15 Hz) and high (0.15-0.40 Hz) frequency powers. Presence and duration of ischemia were also registered. Results: Significant lowering of low density lipoprotein cholesterol occurred in the pravastatin group by day 7 (mean decrease by 23% of total and by 33% of low density lipoprotein cholesterol). At this time point numbers of episodes of ST-depression were low in both groups (2 and 4 on and without pravastatin, respectively). Spectral HRV parameters tended to be higher (VLF power was significantly higher) in pravastatin treated patients. These patients also had a slight insignificant tendency to better tolerance to physical effort on days 14 and 90. Conclusion. Early initiation of therapy with pravastatin in patients with acute unstable angina was at least neutral to myocardial ischemia and was associated with somewhat better HRV.