|Klainman E et al.|
Evaluation of Prognostic Stratification of Patients with Chronic Heart Failure by Recovery Cardiopulmonary Indices Compared to Cardiopulmonary Exercise Indices
Journal of Clinical and Basic Cardiology 2012; 15 (1-4): 13-16
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Keywords: cardiopulmonary exercise testing, heart failure, prognostic factor, VO2 recovery kinetic
Background: Cardiopulmonary exercise testing (CPET) with monitoring of gas exchange parameters provides useful information on exercise capacity and prognosis in congestive heart failure (CHF). Little is known about prognostic importance of recovery cardiopulmonary indices of CPET for all-cause mortality in CHF patients. Objective: The objective of this study is to evaluate the CPET-based recovery cardiopulmonary indices as predictive prognostic factors for death and readmissions. Methods: 104 patients with CHF, 81 males (77.9 %), mean age 50.3 years (SD = 13.9), were studied. 39 patients (37.5 %) had diabetes mellitus (DM), 26 (25.0 %) had COPD, 46 (44.2 %) had ischemic heart disease (IHD), and 74 (71.2 %) had hypertension. All patients underwent CPET, including recovery indices, and were followed between 2000 and 2005 for all-cause mortality and for admission (as end point events). Exercise indices were: HR, BP, O2 consumption (VO2), O2 pulse (O2-P), ventilation (Ve), respiratory exchange ratio (RER), and ventilatory anaerobic threshold (VAT), among others. Recovery indices were: ½ time recovery of VO2 (½VO2-t- Rec.), in sec; ½ time recovery of O2-P (½O2-P-t-Rec.), in sec; and full-time recovery of VO2 (VO2-TRec.), in minutes (min). Results: There were no factors which predicted readmissions. All-cause mortality rate was 24.0 % (n = 25). Significant correlations were demonstrated between all-cause mortality and: peak-Ve (p < 0.007); peak-VO2 (% pred.; p < 0.001); peak-O2-P (p < 0.000); VAT (p < 0.020); ½VO2-t-Rec (p < 0.025); ½O2-P-t-Rec (p < 0.019) ; ½VO2-t-Rec/RER-peak (RER at peak exercise) (p < 0.002); ½O2-P-t-Rec/RER-peak (p < 0.020); ½VO2-t-Rec × RER-peak (p < 0.000); ½O2-P-t-Rec × RER-peak (p < 0.021); ½VO2-t-Rec/ RER-max (maximal RER at exercise or recovery) (p < 0.000); ½O2-P-t-Rec/RER-max (p < 0.013); ½VO2-t-Rec × RER-max (p < 0.003), and ½O2-P-t-Rec × RER-max (p < 0.044). By multivariate logistic regression analysis, peak-Ve (regression coefficient= –0.083), ½VO2-t- Rec/RER-peak (regression coefficient = –0.216), ½VO2-t-Rec/RER-max (regression coefficient = 0.272), and DM (regression coefficient = 0.705) were found as the independent predictors of all-cause mortality. Conclusions: Recovery cardiopulmonary parameters, as definded in the present study, were found to be significant prognostic predictors at least as exercise indices. Thus, it is suggested to complete the CPET with continuing monitoring during the whole recovery period for further evaluation of CHF patients.