Influence of etiology on ventilatory expired gas and prognosis in heart failure

Background: Mechanisms leading to heart failure (HF) are numerous. Etiology-based differences are, however, frequently not taken into account when assessing results of an exercise test. The purpose of this investigation is to: (1) compare subject characteristics and ventilatory expired gas measures demonstrating clinical value between subjects with ischemic and non-ischemic HF. (2) Examine the prognostic value of HF etiology. Methods: 71 subjects (44 male/27 female) diagnosed with compensated HF underwent exercise testing with ventilatory expired gas analysis. Mean age and ejection fraction (EF) were 51.3% (±12.8) and 27.0% (±12.5%) for the entire group. HF etiology was ischemic in 30 subjects (16 male/14 female) and non-ischemic in 41 (28 male/13 female). Results: Age (57.5±10.7 vs. 46.7±12.5, p<0.001), minute ventilation–carbon dioxide production (VE/VCO2) slope (39.5±9.1 vs. 32.6±7.7, p=0.001), and duration of phase 1 kinetics in seconds (46.0±23.0 vs. 30.0±15.6, p=0.001) were significantly higher while peak oxygen consumption (VO2) in ml O2 kg−1 min−1 (12.5±4.7 vs. 16.0±5.2, p=0.006) and partial pressure of end-tidal CO2 (PETCO2) in mm Hg at rest (32.1±4.8 vs. 36.1±8.0, p=0.02) and peak exercise (31.7±4.3 vs. 36.2±5.9, p=0.001) were significantly lower in the ischemic group. Difference in EF did not reach statistical significance (28.4% ±12.5%—ischemic vs. 26.1%±12.5%—non-ischemic, p=0.44). Ischemic etiology was additionally a significant predictor of cardiac-related events (p=0.04). Conclusions: These findings demonstrate noninvasive indicators of cardiac function and prognosis is poorer in subjects with ischemic HF etiology. Consideration of HF etiology may therefore be prudent, particularly when considering prognosis.