Low pulse pressure as a poor-manʼs indicator of a low cardiac index in patients with severe cardiac dysfunction

AIMS: A low pulse pressure (PP) may reflect poor cardiac output (CO), but has not been well characterized by invasive haemodynamic studies. METHODS: We investigated the relationship between PP and cardiac index (CI) in patients with cardiovascular disease including those with normal and impaired cardiac function. Cardiac catheterization data from 1897 patients was analysed. RESULTS: Mean age was 59 years; 57% were men, mean (SD) PP was 65 (25) mmHg and mean (SD) CI was 2.9 (0.8) l/min/m. Correlation between CI and PP was absent if the CI was more than 3 l/min/m, with a weak correlation if CI was between 2 and 3 l/min/m (r = 0.161; P < 0.001). For those with a CI of less than 2 l/min/m, the correlation was much stronger (r = 0.414; P < 0.001). In a multivariable regression analysis, a low PP predicted a low CI, at cardiac indices of less than 3 l/min/m. This was independent of potential confounders, including age, sex, presence of hypertension, presence of heart failure, presence of aortic stenosis, diabetes, renal function, heart rate, systemic vascular resistance, left ventricular end diastolic pressure and mean arterial pressure. CONCLUSION: In patients with a CI of less than 3 l/min/m, a low PP is a marker of a low CI. In patients with severe heart failure and a low CO, PP pressure might be useful as a 'poor-man's' surrogate of CO.