Clinical assessment of external pressure circulatory assistance in acute myocardial infarction: Report of a cooperative clinical trial

The clinical effects of early application of external pressure circulatory assistance (EPCA) in acute myocardial infarction were evaluated in a prospective, randomized trial involving 258 patients in 25 institutions. All patients had mild left ventricular failure and received circulatory assistance within the first 24 hours after the onset of symptoms. There were no significant differences between the treatment and control groups, consisting of 142 patients and 116 patients, respectively, with regard to age, sex, race, previous cardiac history, electrocardiographic location of myocardial infarction, Norris prognostic index, admission heart rate, blood pressure and chest roentgenogram, and time from onset of symptoms to hospital admission. There were also no differences between the treatment and control groups with regard to antiarrhythmic, positive inotropic, diuretic and vasodilator therapy. Hospital mortality was significantly decreased, compared with that of control patients, in the group receiving 4 or more hours of external pressure circulatory assistance within the first 24 hours after admission (mortality rate 6.5 percent [7 of 108] in treatment group versus 14.7 percent [17 of 116] in control group, p < 0.05). Circulatory assistance for 3 or more hours was also associated with a lower mortality rate in the subgroup (patients 46 or more years old) to which mortality in this study was confined (mortality rate 8.3 percent [9 of 109] in the treatment group versus 17.5 percent [17 of 97] in the control group, p < 0.05). For the combined group of patients with 3 or more and 4 or more hours of treatment, circulatory assistance was associated with significant lessening (p < 0.05 to < 0.01) of morbidity as manifested by recurrent chest pain, progression of cardiac failure, occurrence of ventricular fibrillation, change in heart size and clinical cardiac functional status at discharge. These data support further application and investigation of external pressure circulatory assistance in myocardial infarction.