Beneficial effects of long-term metoprolol therapy on cardiac haemodynamics in patients with mitral stenosis in sinus rhythm--a randomised clinical trial.

We conducted a placebo controlled randomised clinical trial to evaluate the effects of 6 months therapy with metoprolol on resting and exercise haemodynamics in 31 patients with isolated mitral stenosis in sinus rhythm. Twenty six of them (placebo n = 13, metoprolol n = 13) completed the study protocol. Their mean age was 23.1 +/- 7.9 years and the mean mitral valve area was 0.93 +/- 0.25 cm2. The dose of metoprolol ranged between 50-100 mg per day. The primary outcome variables for the study were the resting and exercise mean pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) and the secondary outcome variables consisted of resting and exercise heart rate, mean pulmonary artery pressure (PAP), mean pulmonary vascular resistance (PVR) and clinical improvement on visual analog scale. These outcome variables were assessed blindly. The resting and exercise mean PCWP (mmHg) increased by 9.1 +/- 3.1 and 16.4 +/- 6.4 on placebo and 2.5 +/- 2.1 and -4.6 +/- 2.3 on metoprolol after 6 months therapy. These differences were statistically significant (p < 0.01). The resting and exercise CI (liters/min/m2) decreased by 0.2 +/- 0.1 and 0.1 +/- 0.1 on placebo and 0.3 +/- 0.5 and 0.3 +/- 1.0 on metoprolol. These haemodynamic effects were accompanied with much better symptomatic improvement in patients treated with metoprolol. The differences in change in mean PAP and PVR in two groups were statistically not significant. Our results suggest that the symptomatic patients with MS, waiting for definitive intervention for 6 months or less, would benefit if given beta blockers during this period.