Validation of peak exercise oxygen consumption and the Heart Failure Survival Score for serial risk stratification in advanced heart failure

Abstract

The Heart Failure Survival Score (HFSS) and peak exercise oxygen consumption (VO2) accurately assess mortality in ambulatory patients who have advanced heart failure and are referred for initial cardiac transplant evaluation. We investigated the prognostic value of the HFSS and peak VO2 when applied serially to these patients. This study included 227 adults (mean age +/- SD 52 +/- 10 years old) who presented for reevaluation >60 days after initial evaluation (352 +/- 238 days). The HFSS was determined from mean arterial blood pressure, heart rate, left ventricular ejection fraction, serum sodium, peak VO2, heart failure etiology, and width of QRS complex. Survival without reevaluation, United Network of Organ Sharing 1 transplant, or left ventricular assist device was determined by the Kaplan-Meier method with censoring at United Network of Organ Sharing 2 transplant. Survival differed by HFSS stratum (p <0.001) and by peak VO2 stratum (p <0.001). Patients whose HFSS or peak VO2 deteriorated from low risk to medium or high risk had lower survival rates than did patients whose values remained at low risk (p <0.01 and p <0.001, respectively). Patients who started at medium or high risk and improved to low risk tended to have higher survival rates than those who remained medium or high risk (p = 0.06 and p <0.16, respectively). Patients who improved to low risk had a 1-year survival rate of 72% for HFSS and peak VO2. However, patients who improved to low risk and were treated with beta blockers had a 1-year survival rate (89% for HFSS and 83% for peak VO2) comparable to that after transplant (84%). Peak VO2 and the HFSS can be successfully used for serial evaluation of mortality risk in ambulatory patients who have advanced heart failure.