Comparison of trimetazidine with atenolol in patients with syndrome X: effects on diastolic function and exercise tolerance.

Background: Trimetazidine has been shown to improve anginal symptoms without altering hemodynamic variables in patients with coronary artery disease. The aim of this study was to compare the effect of trimetazidine and atenolol upon symptoms, resting left ventricular filling dynamics and exercise tolerance.

Methods: Sixteen patients (3 males, 13 females, mean age 62 +/- 7 years) were randomized to receive trimetazidine for 2 weeks (20 mg 3 times daily) or atenolol (100 mg daily), according to a double-blind, randomized, cross-over, placebo-controlled design. At the end of each treatment period patients underwent symptom-limited exercise testing, an echocardiogram and a Doppler assessment of transmitral flow pattern. Daily life anginal symptoms were annotated on a diary throughout the study. Two patients discontinued trimetazidine because of severe palpitations and only 14 patients completed the study.

Results: Atenolol significantly reduced the number of anginal episodes as compared to placebo or trimetazidine (0.44 +/- 0.53, 4.8 +/- 4, 2.9 +/- 4.9, p < 0.01). On atenolol, the exercise test was negative in 8 patients, but none of the patients had a negative test while on trimetazidine. Atenolol increased both time to 1 mm ST segment depression (668 +/- 213 vs 838 +/- 81 s, p < 0.05) and Doppler-derived indices of ventricular filling (E/A ratio 0.87 +/- 0.20 vs 1.21 +/- 0.26, p < 0.05).

Conclusions: These results confirm the beneficial effects of atenolol in improving symptoms, exercise performance and diastolic function in syndrome X patients. Trimetazidine did not exert any significant effect on any of the analyzed variables. Since trimetazidine has been previously shown to improve myocardial ischemia in patients with overt coronary artery disease to a similar extent of beta-blockers, it is likely that other mechanisms are responsible for angina in patients with syndrome X.