Exercise oscillatory ventilation may predict sudden cardiac death in heart failure patients

Objectives The purpose of this study was to test the ability of cardiopulmonary exercise testing (CPET)-derived variables as sudden cardiac death (SCD) predictors. Background The CPET variables, such as peak oxygen uptake (VO2), ventilatory requirement to carbon dioxide (CO2) production (VE/VCO2) slope, and exercise oscillatory breathing (EOB), are strong predictors of overall mortality in chronic heart failure (CHF) patients. Even though up to 50% of CHF patients die from SCD, it is unknown whether any of these variables predicts SCD. Methods One hundred fifty-six CHF patients (mean age: 60.9 +/- 9.4 years; mean ejection fraction: 34.9 +/- 10.6%) underwent CPET. Subjects were tracked for sudden versus pump-failure cardiac mortality over 27.8 +/- 25.2 months. Results Seventeen patients died from SCD, and 17 died from cardiac pump failure. Survivors showed significantly higher peak VO2 (16.8 +/- 4.5 ml center dot kg(-1)center dot min(-1)) and lower VE/VCO2 slope (32.8 +/- 1 6.4) and prevalence of EOB (20.3%), compared with subjects who experienced arrhythmic (13.5 +/- 3.2 ml center dot kg(-1)center dot min(-1); 41.5 +/- 11.4; 100%) or nonarrhythmic (14.1 +/- 4.7 ml center dot kg(-1)center dot min(-1); 38.1 +/- 7.3; 47.1%) deaths (p < 0.05). At Cox regression analysis, all variables were significant univariate predictors of both sudden and pump failure death (p < 0.01). Multivariate analysis, including left ventricular (LV) ejection fraction, LV end systolic volume, and LV mass selected EOB, was the strongest predictor of both overall mortality (chi-square: 38.7, p < 0.001) and SCD (chi-square: 44.7, p < 0.001), whereas VE/VCO2 slope was the strongest ventilatory predictor of pump failure death (chi-square: 11.8, p = 0.001). Conclusions Exercise oscillatory breathing is an independent predictor of SCD in patients with CHF and might help as an additional marker for prioritization of antiarrhythmic strategies. (J Am Coll Cardiol 2007;50:299-308) (c) 2007 by the American College of Cardiology Foundation.