BENEFICIAL-EFFECTS OF A SINGLE-DOSE OF QUINAPRIL ON LEFT-VENTRICULAR PERFORMANCE IN CHRONIC MITRAL REGURGITATION

To evaluate the effect of a single dose of the angiotensin-converting enzyme inhibitor quinapril on left ventricular (LV) performance and si ze in patients with moderate to severe chronic mitral regurgitation (M R), 12 patients with angiographically proven isolated MR grade II to I II and no evidence of coronary artery disease were studied. In all pat ients a baseline right heart catheterization and simultaneous radionuc lide angiogram were performed at rest and during supine exercise (maxi mum 100 W) as well as 2 hours after oral administration of 10 mg of qu inapril. Quinapril reduced heart rate slightly and lowered mean blood pressure at rest and during maximal exercise (p <0.05). Systemic vascu lar resistance at rest was decreased from 1,484 +/- 505 to 1,150 +/- 4 27 dynes s cm(-5) and with maximal exercise from 999 +/- 455 to 734 +/ - 395 dynes s cm(-5) (p <0.005). Pulmonary capillary arterial pressure at rest decreased from 13 +/- 6 to 10 +/- 4 mm Hg (p = 0.01) and duri ng maximal exercise from 29 +/- 10 to 20 +/- 7 mm Hg (p = 0,001). LV e nd-diastolic volume at rest (146 +/- 26 ml/m(2)) decreased after admin istration of quinapril to 128 +/- 24 ml/m(2) (p = 0.001) and was also reduced during exercise (p = 0.001). LV end-systolic volume decreased from 63 +/- 43 to 49 +/- 35 ml/m(2) at rest (p = 0.001) and with maxim al exercise from 56 +/- 49 to 44 +/- 39 ml/m(2) (p <0.01). After quina pril administration, LV ejection fraction at rest improved from 0.59 /- 0.20 to 0.62 +/- 0.18 (p <0.05) and during maximal exercise from 0. 64 +/- 0.21 to 0.67 +/- 0.19 (p = 0.06). Furthermore, quinapril decrea sed regurgitant fraction at rest from 0.43 +/- 0.10 to 0.28 +/- 0.11 ( p <0.001) and during maximal exercise from 0.41 +/- 0.12 to 0.27 +/- 0 .10 (p <0.001). Concomitantly regurgitant volume declined from 36 +/- 17 to 24 +/- 11 ml/m(2) at rest and was also reduced during maximal ex ercise (p <0.001). The data demonstrate that pre- and afterload reduct ion with quinapril decreases MR and reduces LV volumes and end-diastol ic pressure, thus improving LV performance. If these beneficial effect s can be maintained during long-term treatment, LV dysfunction and tim ing for mitral valve surgery may be markedly delayed in some patients.