The association between low blood pressure and prognosis in the general population has been controversial, with some reports suggesting an increased mortality for patients with the lowest blood pressures. Whereas many standard heart failure therapies decrease blood pressure, the relationship between mortality and blood pressure in patients with heart failure has not been previously evaluated.

We used the Digitalis Investigation Group trial database to evaluate retrospectively the relationship among systolic blood pressure (SBP), diastolic blood pressure (DBP), and survival among 5747 patients with New York Heart Association class II or III heart failure and left ventricular ejection fraction ≤0.45. Cox proportional hazards models were used to identify covariates predictive of long-term mortality.

The adjusted all-cause mortality rate during the entire study period for patients in the lowest SBP group (<100 mm Hg) was 50% and was significantly higher than that of the reference group of patients with SBP of 130 to 139 mm Hg, which had a mortality rate of 32% (hazard ratio 1.65, 95% CI 1.25-2.17, P < .001). The relationship between SBP and mortality was significant (P < .001) and nonlinear (P = .009). The relationship between DBP and mortality was significant (P < .001), with the highest mortality seen in patients with DBP <60 mm Hg.

In patients with systolic dysfunction (left ventricular ejection fraction ≤0.45) and New York Heart Association classes II and III symptoms, lower SBPs and DBPs were associated with greater mortality.