Clinical results with prenalterol in patients with heart failure

The hemodynamic effect of 75 to 225 microgram/kg prenalterol (PNL) intravenously were studied at rest and during exercise in eight patients with chronic congestive heart failure (CHF) after myocardial infraction (three patients), valvular surgery (three patients), and congestive cardiomyopathy (two patients). All head New York Health Association functional class III and IV CHF and were receiving digitalis and diuretics. With PNL at rest, left ventricular filling pressure (LVFP) fell from 17 to 12 mm Hg, cardiac index (CI) rose from 2.1 to 2.9 L/min/m2, heart rate (HR) increased mildly, systemic vascular resistance (SVR) declined moderately, and peripheral arterial pressure was unchanged. During PNL exercise compared with control, LVFP rise was less and CI, HR, and SVR responses were similar; dyspnea and angina were reduced in most patients. The eight patients were than given PNL orally, 30 to 200 mg/day, versus placebo for 6 days with comparative evaluation by echocardiogram, systolic time intervals (STI), exercise test, and continuous ECG. With PNL orally five of eight patients improved symptomatically, ejection fraction increased from 0.44 to 0.53, and STI preejection period shortened by 10 msec, without change in resting HR or systemic arterial blood pressure. The incidence of ventricular premature beats was not increased. PNL orally vs placebo exercise capacity increased 10%. Thus PNL may be of value for long-term CHF treatment in addition to conventional therapy.