Prognostic Significance of the Double Pressure Reserve in Patients with Chronic Heart Failure

Introduction: The double pressure reserve (DPR) has recently been shown to have greater prognostic power than metabolic equivalents, heart rate indices, and systolic blood pressure in healthy subjects. It is unclear whether DPR offers any prognostic value in a heart failure population where variables derived from metabolic gas exchange data provide important prognostic information. Methods: Patients underwent a symptom-limited, treadmill-based exercise test with metabolic gas exchange measurements using the modified Bruce protocol. DPR was calculated as the product of peak systolic blood pressure and peak heart rate subtracted from the product of resting systolic blood pressure and resting heart rate values. Results: 363 patients (mean ± SD; age 74±11 years; 81% males; left ventricular ejection fraction 34±6%; peak VO2 19.0 ± 5.1 mL·kg -1 ·min -1 ; VE/VCO2 slope 37 ± 9; double pressure reserve 10,510 ± 6,046 mmHg·beat -1 ) were included in the study. Peak VO2 (hazard ratio (HR) = 0.87; P<0.0001, 95% confidence intervals (CI) = 0.75-0.99), VE/VCO2 slope (HR=1.03; P=0.04; 95% CI =1.00-1.06), and age (HR=1.02; P=0.09; 95% CI =0.98-1.05) were the strongest independent predictors of mortality. DPR was not a univariate predictor of mortality (P=0.7; HR=1.0; 95% CI = 0.99-1.0). Conclusion: DPR does not predict mortality in patients with CHF. Traditional prognostic markers derived from metabolic gas exchange including peak VO2 and the VE/VCO2 slope are more important.