[Symptomatic mitral valve prolapse. Left ventricular dysfunction and beneficial effect of digitalis]

To study the left ventricular function by M-mode echocardiography in symptomatic patients with primary mitral valve prolapse (MVP), without significant mitral regurgitation, during the phenylephrine test, before and after digitalization.

Thirty one patients with MVP and 10 normal subjects as a control group were studied by M mode echocardiography: Percentage of systolic shortening (DD), ejection fraction (EF) and mean velocity of circumferential fibers shortening (Vcf) were measured. The echocardiographic recordings were obtained at rest and during the continuous infusion of phenylephrine (40-60 micrograms/min) in order to allow an increase of 20-30 mmHg in systolic pressure.

At rest, cardiac size and function were normal in both groups. During phenylephrine infusion in 27 patients a decrease in DD (from 37.7 +/- 4.6 to 31.0 +/- 4.0, p < 0.001); in EF (from 0.76 +/- 0.05 to 0.66 +/- 0.6, p < 0.001); in Vcf (from 1.05 +/- 0.77 to 0.76 +/- 0.13, p < 0.001) were observed. From this group 20 patients received digoxin. After the digitalization the phenylephrine test did not cause changes in DD (from 38.3 +/- 5.0 to 39.2 +/- 3.8, NS); in EF (from 0.77 +/- 0.06 to 0.77 +/- 0.04, NS); in Vcf (from 1.05 +/- 0.19 to 0.94 +/- 0.13, NS). These patients during the submaximal exercise test, showed significant increases at the total work load (from 617 +/- 248 to 982 +/- 244 watts, p < 0.001) and cardiac efficiency (from 25.0 +/- 11.5 to 37.2 +/- 10.4, p < 0.001). On the other hand the phenylephrine infusion in the control group did not result in changes in DD, EF and Vcf.

Symptomatic patients with primary MVP showed total recovering of left ventricular dysfunction with digitalization during the phenylephrine test, with improvement of cardiac efficiency.