Association of Systemic Vascular Resistance Analog and Cardiovascular Outcomes: The Heart and Soul Study

Background Systemic vascular resistance (SVR) is an integral component of the hemodynamic profile. Previous studies have demonstrated a close correlation between an estimated SVR analog (eSVR) based on echocardiographic methods and SVR by direct hemodynamic measurement. However, the prognostic impact of eSVR remains unestablished. Methods and Results Study participants with established coronary artery disease from the Heart and Soul Study formed this study cohort. We defined Doppler-derived eSVR as the ratio of systolic blood pressure to left ventricular outflow tract velocity time integral. Study participants were separated based on baseline eSVR tertile: <5.6, 5.6 to <6.9, and ≧6.9. An elevated eSVR was defined as an eSVR in the third tertile (≧6.9). Follow-up eSVR was calculated at the fifth year of checkup. Cardiovascular outcomes included heart failure, major cardiovascular events, and all-cause death. Among the 984 participants (67±11 years old, 82% men), subjects with the highest baseline eSVR tertile were the oldest, with the highest systolic blood pressure and lowest left ventricular outflow tract velocity time integral. A higher eSVR was associated with increased risk of heart failure, major cardiovascular events, and death. The hazard ratio for major cardiovascular events was 1.38 (95% CI, 1.02-1.86, P=0.03) for subjects with the highest eSVR tertile compared with the lowest. In addition, those with a persistently elevated eSVR during follow-up had the most adverse outcomes. Conclusions An elevated eSVR, derived by the ratio of systolic blood pressure and left ventricular outflow tract velocity time integral, was more closely correlated with cardiovascular events than systolic blood pressure alone. Repeatedly elevated eSVR was associated with more adverse outcomes.