Cardiac involvement in cystic fibrosis: early noninvasive detection and vasodilator therapy.

Cardiac involvement in cystic fibrosis (CF) occurs commonly but may remain undetected by usual evaluation in its early stages when right ventricular dysfunction (RVD) may be treatable. To assess the role of vasodilator therapy for early RVD in CF, we performed a prospective study in 23 ambulatory CF patients with mild CF (clinical score m = 79 +/- 8, range 61 to 90). Echocardiography (echo) and radionuclide angiography (RA) were performed at rest and with exercise stress testing (EST) in all 23 to select patients with early RVD. Thirteen of twenty-three had RVD on echo or RA evidenced by increased RV dimensions (P less than 0.001) on echo and decreased RV ejection fraction (EF) on RA (P less than 0.01) but 30% of these patients were abnormal only with EST. All 13 with RVD underwent inpatient double-blinded randomization to receive placebo or hydralazine orally without changing other standard therapy. Nine of thirteen received hydralazine (2 mg/kg/day) for 3 days. With hydralazine no change from placebo was seen on any echo or RA measurement at rest or with EST other than left ventricular STI which fell (P less than 0.05). These data indicate: 1) EST with echo and RA detects RVD in CF earlier than resting studies, 2) patients with mild CF (clinical score less than 85) frequently have RVD on EST, and 3) hydralazine does not improve RVD in CF even very early in its development.