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 (P(ET)CO2) 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.