Development of a Ventilatory Classification System in Patients With Heart Failure

• Published in: Circulation (New York, N.Y.) Vol. 115; no. 18; pp. 2410 - 2417
• Main Authors: Arena, Ross, Myers, Jonathan, Abella, Joshua, Peberdy, Mary Ann, Bensimhon, Daniel, Chase, Paul, Guazzi, Marco
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 08.05.2007
• Subjects: Adult; Aged; Biological and medical sciences; Blood and lymphatic vessels; Carbon Dioxide - analysis; Cardiology. Vascular system; Cardiovascular system; Cohort Studies; Disease-Free Survival; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Exercise Test; Female; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; Heart Diseases - mortality; Heart Failure - physiopathology; Heart Transplantation - statistics & numerical data; Heart-Assist Devices - statistics & numerical data; Humans; Italy - epidemiology; Kaplan-Meier Estimate; Lymphatic system; Male; Medical sciences; Middle Aged; Pharmacology. Drug treatments; Prognosis; Prospective Studies; Pulmonary Ventilation; Risk Assessment; ROC Curve; Severity of Illness Index; Stroke Volume; United States - epidemiology; Vasodilator agents. Cerebral vasodilators; Vertebrates: cardiovascular system; United States; Italy; Physical exercise; Human; Heart failure; Prognosis; Heart disease; Classification; ventilation; Cardiovascular disease; exercise
• ISSN: 0009-7322; 1524-4539; 1524-4539
• DOI: 10.1161/CIRCULATIONAHA.107.686576

Background— Ventilatory efficiency, commonly assessed by the minute ventilation (V̇ e )–carbon dioxide production (V̇ co 2 ) slope, is a powerful prognostic marker in the heart failure population. The purpose of the present study is to refine the prognostic power of the V̇ e /V̇ co 2 slope by developing a ventilatory class system that correlates V̇ e /V̇ co 2 cut points to cardiac-related events. Methods and Results— Four hundred forty-eight subjects diagnosed with heart failure were included in this analysis. The V̇ e /V̇ co 2 slope was determined via cardiopulmonary exercise testing. Subjects were tracked for major cardiac events (mortality, transplantation, or left ventricular assist device implantation) for 2 years after cardiopulmonary exercise testing. There were 81 cardiac-related events (64 deaths, 10 heart transplants, and 7 left ventricular assist device implantations) during the 2-year tracking period. Receiver operating characteristic curve analysis revealed the overall V̇ e /V̇ co 2 slope classification scheme was significant (area under the curve: 0.78 [95% CI, 0.73 to 0.83], P <0.001). On the basis of test sensitivity and specificity, the following ventilatory class system was developed: (1) ventilatory class (VC) I: ≤29; (2) VC II: 30.0 to 35.9; (3) VC III: 36.0 to 44.9; and (4) VC IV: ≥45.0. The numbers of subjects in VCs I through IV were 144, 149, 112, and 43, respectively. Kaplan-Meier analysis revealed event-free survival for subjects in VC I, II, III, and IV was 97.2%, 85.2%, 72.3%, and 44.2%, respectively (log-rank 86.8; P <0.001). Conclusions— A multiple-level classificatory system based on exercise V̇ e /V̇ co 2 slope stratifies the burden of risk for the entire spectrum of heart failure severity. Application of this classification is therefore proposed to improve clinical decision making in heart failure.