Abstract 3195: Is the Extent of Exercise VO2 Oscillations Related to the Severity and Prognisis of Heart Failure?
Purpose: Exercise VE or VO2 oscillation (OSC) as well as exercise hyperventilation is an ominous sign in patients with heart failure. However, unlike exercise hyperventilation that is readily evaluated by VE/VCO2 slope, OSC have only been estimated in a qualitative manner (i.e., “present” or “absent”). We hypothesized that the extent of OSC may be related to the severity and prognosis of heart failure.
Methods: From a consecutive series of >4700 cardiopulmonary bicycle exercise tests for recent 5.5 years, we examined the presence of OSC both by visual inspection and by our previously developed method where we estimated Ratio (Low frequency power/Total power) indicative of abnormal slow VO2 OSC (0.5–1.25 cycle/min) by repeating FFT power spectrum analysis (4-min time-window, overlapping every 30 sec).
Results: We found VO2 OSC (defined as Ratio >34.2%) in 175 patients, who were grouped by a median split into Group-H with moderate-to-pronounced OSC (Ratio >42, n=88) and Group-L with mild OSC (Ratio <42, n=87). Compared with Group-L, Group-H had lower peak VO2 (17.5 ± 4.4 vs 20.9 ± 4.4 ml/min/kg, p< 0.0001) and exhibited higher VE/VCO2 slope (38.3 ± 12.4 vs 32.5±5.7, p=0.0001), BNP level (308 ± 306 vs 172 ± 144 pg/ml, p<0.001), and NYHA functional class (1.9 ± 0.7 vs 1.6 ± 0.6, p=0.006). During the median follow-up period of 1093 days, cardiac deaths and hospital admissions for heart failure more frequently occurred in Group-H than in Group-L (see Figure⇓).
Conclusions: The data indicate that the more pronounced the exercise VO2 oscillations, the more severe the status of heart failure. Moderate-to-pronounced forms of exercise VO2 oscillations predict an even poorer prognosis.