Response to Cardiac Resynchronization Therapy : The Muscular Metabolic Pathway

Abstract EN

Background.

Changes in peripheral muscle in heart failure lead to a shift from aerobic to early anaerobic metabolism during exercise leading to ergoreflex overactivation and exaggerated hyperventilation evaluated by the VE/VCO2 slope.

Methods.

50 patients (38 males, 59±12 years) performed cardio-pulmonary exercise test with gaz exchange measurement and echocardiographic evaluation before and 6 months after CRT.

Results.

The peak respiratory exchange (VCO2/ VO2) ratio was significantly reduced from 1.16 ± 0.14 to 1.11± 0.07 (P< .05) and the time to the anaerobic threshold was increased from 153±82 to 245±140 seconds (P=.01).

Peak VO2, VE/VCO2, peak circulatory power and NYHA were improved after CRT (13±4 to16±5 ml/kg/min (P<.05), 45±16 to 39±13 (P<.01), 1805±844 to 2225±1171 mmHg.ml/kg/min (P<.01) and 3±0.35 to 1.88±0.4 (P=.01)).

In addition, left ventricular ejection fraction and end-systolic volumes were improved from 24±8 to 29±7% (P<.01) and from 157±69 to 122±55 ml (P<.01).

Conclusion.

We suggest that CRT leads to an increase in oxidative muscular metabolism and postponed anaerobic threshold reducing exaggerated hyperventilation during exercise.