Key result
Cardiac resynchronisation therapy significantly increased exercise cardiac output by 19.3% (P=0.0048) and peak cardiac power output by 37.2% (P=0.0008) in patients with severe heart failure.
Why the study?
Does CRT pacemaker implantation improve exercise capacity and functional reserve in patients with severe heart failure and widened QRS?
Cohort (n=17)
Does CRT pacemaker implantation improve exercise capacity and functional reserve in patients with severe heart failure and widened QRS?
CRT significantly improves cardiac flow, pressure, and power-generating capacity during exercise in patients with severe heart failure, correlating with improved exercise capacity and symptoms.
Answers are grounded in this paper and cite their sources.
CRT may augment exercise hemodynamics in severe HF; hypothesis-generating and should not yet change practice.
BACKGROUND: While information on how cardiac resynchronisation therapy (CRT) affects cardiac performance at rest is readily available, the mechanisms whereby CRT alters cardiac function during maximal exercise are unclear. AIMS: We examined the medium-term effects of CRT on cardiac and physical functional reserve of patients with severe heart failure (CHF) and prolonged QRS duration. METHODS: Seventeen consecutive patients with severe CHF (NYHA III-IV) and widened QRS underwent maximal cardiopulmonary exercise testing with non-invasive central haemodynamic measurements before and 6-8 weeks after CRT pacemaker implantation. RESULTS: After CRT there were significant increases in exercise cardiac output by 19.3% (P=0.0048) from 9.5+/-3.4 l min(-1), peak mean arterial blood pressure by 14.1% (P=0.0001) from 91.3+/-13.6 mm Hg, and peak cardiac power output by 37.2% (P=0.0008) from 1.92+/-0.74 W. There were no significant changes in these variables at rest. Exercise duration (+42.3%, P=0.0002), NYHA functional class (P=0.0001) and SF-36 symptom score (P=0.0006) were also significantly improved. Powerful surrogate indicators of prognosis were also significantly improved with CRT: peak O(2) consumption (+20.9%, P=0.0007), VE/VCO(2) slope (-20.0%, P=0.005) and circulatory power (+42.0%, P=0.0012). CONCLUSION: In this cohort of patients, post-implant CRT significantly improved the flow-, pressure- and power-generating capacity of the failing hearts. This may be causally related to the improvements observed in exercise capacity, functional class and symptom scores.
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Schlosshan et al. (2005) conducted a cohort in severe heart failure (CHF) and prolonged QRS duration (n=17). Cardiac resynchronisation therapy (CRT) vs. Baseline (before CRT) was evaluated on exercise cardiac output (+19.3%, p=0.0048). Cardiac resynchronisation therapy significantly increased exercise cardiac output by 19.3% (P=0.0048) and peak cardiac power output by 37.2% (P=0.0008) in patients with severe heart failure.
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