Relation between admission time, haemodynamic measurements, and prognosis in acute myocardial infarction.

Pulmonary arterial end-diastolic pressure, cardiac index, and stroke work index were measured via a thermistor-tipped balloon catheter and monitored for 5151 hours in 226 patients admitted with an acute myocardial infarction (184 survivors and 42 non-survivors). Mortality was related to time of admission after onset of symptoms of infarction. Of 69 patients in group A 13 died in hospital (18 8%) one to four hours after onset; in group B (five to eight hours after onset) eight of 71 patients (11%) died five to eight hours after onset; four of 26 patients in group C (15%) died nine to 12 hours after onset; 15 of 42 patients (36%) in group D died 13 to 24 hours after onset; and two of 18 patients in group E died (11%) more than 24 hours after onset. Irrespective of admission time, haemodynamic findings in survivors were significantly better than in non-survivors. During the first eight to 12 hours after onset of infarction cardiac index and stroke work index were normal or above normal, with raised left ventricular filling pressures. In patients admitted later, this compensatory mechanism had often collapsed. Where pump failure with subnormal cardiac index and stroke work index were present mortality was increased. All four patients dying from acute myocardial rupture had significantly higher values of cardiac index and stroke work index and lower values of pulmonary artery end-diastolic pressure compared with those dying from other causes.