The impact of impaired versus preserved systolic function on survival of patients with heart failure was investigated in 78 patients with decompensated heart failure. Patients were classified on the basis of their left ventricular systolic performance, as defined by fractional shortening (FS); group I (n = 56) had impaired systolic function (FS less than 24%) and group II (n = 22) had preserved systolic function (FS greater than or equal to 24%). Mean ejection fraction was 15 +/- 5% and 40 +/- 13% for these groups, respectively. By the end of 48 months, 36 patients in group I had died compared with only 22 patients in group II (p less than 0.05). Both systolic and diastolic blood pressure were significantly lower in the deceased patients compared with the survivors in group I (p less than 0.05). There was a trend for an opposite direction in the relationship of blood pressure to mortality in group II. We conclude that the prognosis of patients with heart failure and preserved systolic function is more favorable than that of those with impaired function, and that blood pressure may have a differential prognostic meaning in the two groups.