PERIODIC BREATHING IS ASSOCIATED WITH INCREASED MORTALITY RISK IN PATIENTS WITH CONGESTIVE HEART FAILURE

Abstract

1263 Periodic breathing (PB) frequently occurs in patients with congestive heart failure (CHF) due to oscillations of oxygen consumption (VO2). Although Cheyne-Stokes respirations are associated with severe heart failure, the prognostic importance of PB is unknown. We reviewed gas exchange data obtained on all patients referred to the University of Michigan for transplant evaluation over an 8 month period who underwent maximal cardiopulmonary exercise testing (peak respiratory exchange ratio (RER) ≥ 1.1). All patients with CHF for at least 6 months duration, left ventricular ejection fraction (EF) ≤ 40%, and no evidence of improving ventricular function were included. Resting gas exchange was analyzed for PB, and the magnitude of oscillations was determined by the difference between the peak and nadir values divided by the mean value. PB was defined as the presence of oscillating ventilation during rest which was ≥ 30% during 2 consecutive cycles. Each PB subject was paired with at least one subject from the comparison group who were gender, peak VO2 (± 2ml/kg/min), and age matched (± 2 yrs). Heart failure survival score (HFSS) and strata, previously validated indicators of mortality, were calculated for each patient. HFSS and other clinical characteristics were compared by paired t-tests. Comparison of HFSS strata was performed by Fisher's exact test. The following characterizes the PB and comparison groups respectively, n= 16 / 31, age 54 / 54, EF 19 / 20, serum sodium 138 / 139, peak VO2 14.7 / 14.8. Mean ventilatory oscillation was 72.3% for the PB group. PB risk stratification tended to be higher risk than the comparison group (PB: 5 low, 6 middle, 5 high vs. control: 8 low, 8 middle, 0 high risk, p=.071) and the HFSS tended to be worse (Mean 7.76 vs. 8.18 p=.091). In conclusion, analysis of this sample suggests that PB at rest is associated with an increased mortality risk.