Key result
CRT optimization by iterative cardiac output measurements using inert gas rebreathing significantly improved 6-minute walk distance compared to standard programming (456 vs 417 m; P<0.001).
Why the study?
Does iterative CRT optimization using inert gas rebreathing improve exercise capacity and quality of life in patients on CRT?
RCT (n=24)
blinded
randomized
Does iterative CRT optimization using inert gas rebreathing improve exercise capacity and quality of life in patients on CRT?
Absolute Event Rate: 456% vs 417%
p-value: p=<0.001
CRT optimization using noninvasive cardiac output measurements via inert gas rebreathing significantly improves exercise capacity, NYHA class, and quality of life compared to standard programming.
Supports iterative inert gas rebreathing optimization in CRT practice; extends randomized evidence for individualized programming.
BACKGROUND: Many invasive and noninvasive methods have been proposed for guiding optimal programming of cardiac resynchronization therapy (CRT) devices. However, results are not satisfying. Preliminary results suggest that cardiac output (CO) measurements using inert gas rebreathing (IGR) might be an eligible method to tailor atrioventricular (AV) and ventriculo-ventricular (VV) programming. The aims of the present study were: (1) to evaluate whether an optimization of CRT can be obtained by noninvasive CO measurements and (2) to evaluate whether acute hemodynamic improvements obtained by this approach relate into increase in cardiac exercise capacity. METHODS: In 24 patients on CRT, iterative VV- and AV-delay optimization was done using the IGR method. This blinded, randomized, crossover study compared the responses to optimization during two periods: a 4-week optimized and a 4-week standard programming. Exercise capacity after optimization was assessed after each period by New York Heart Association (NYHA) classification, a 6-minute walking test, and quality of life (QoL) questionnaire. RESULTS: CO could be determined by IGR in all patients. The NYHA class decreased by 17.8% (2.8 ± 0.3 vs 2.3 ± 0.4, P < 0.001), the mean (± standard deviation) distance walked in 6 minutes was 9.3% greater after optimization (456 ± 140 m vs 417 ± 134 m, P < 0.001), and the QoL improved by 14.5% (41.8 ± 10.4 vs 36.5 ± 9.5, P < 0.001). The portion of responders to CRT increased from 66.5% to 87.5%. CONCLUSION: CRT optimization by iterative CO measurements leads to an increase in CO and an improvement of exercise capacity. Our results suggest that this method might become an important additive tool to adjust CRT programming.
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Reinsch et al. (2010) conducted an RCT in Cardiac resynchronization therapy (n=24). Iterative VV- and AV-delay optimization using inert gas rebreathing (IGR) vs. Standard programming was evaluated on 6-minute walking test distance (p=<0.001). CRT optimization by iterative cardiac output measurements using inert gas rebreathing significantly improved 6-minute walk distance compared to standard programming (456 vs 417 m; P<0.001).
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