Clinical outcomes of the AdaptResponse trial
Authors: Kazuo Komamura, Mitsunori Iwase
Journal: The Lancet (2024)

In the largest and longest randomised controlled trial of cardiac resynchronisation therapy (CRT) to date, Bruce L Wilkoff and colleagues showed that adaptive CRT did not significantly reduce the incidence of all-cause death or intervention for heart failure decompensation compared with conventional biventricular CRT.1Wilkoff BL Filippatos G Leclercq C et al.Adaptive versus conventional cardiac resynchronisation therapy in patients with heart failure (AdaptResponse): a global, prospective, randomised controlled trial.Lancet. 2023; 402: 1147-1157Summary Full Text Full Text PDF PubMed Google Scholar The reason for no difference between the two groups might be the number of patients who exited the study prematurely and the low use of guideline-indicated heart failure medications. The reasons are likely to be multifactorial, but it is unclear whether the position of the left ventricular pacing is necessarily optimal. The left ventricular pacing lead position is important in relation to the clinical and mechanical response to CRT. Both lead placement, guided by cardiac imaging,2Sommer A Kronborg MB Nørgaard BL et al.Multimodality imaging-guided left ventricular lead placement in cardiac resynchronization therapy: a randomized controlled trial.Eur J Heart Fail. 2016; 18: 1365-1374Crossref PubMed Scopus (98) Google Scholar and positioning, determined by the electrical latency in intracardiac electrograms,3Yagishita D Yagishita Y Kataoka S et al.Left ventricular stimulation with electrical latency predicts mortality in patients undergoing cardiac resynchronization therapy.JACC Clin Electrophysiol. 2021; 7: 796-805Crossref PubMed Scopus (4) Google Scholar effectively improve the CRT response. The paced morphology of the electrograms recorded by the CRT device can reveal the effectiveness of the pacing. A highly effective CRT pacing rate is associated with a high prevalence of CRT responders and low risk of hospitalisation for heart failure.4Oka S Ueda N Ishibashi K et al.Significance of effective cardiac resynchronization therapy pacing for clinical responses: an analysis based on the effective cardiac resynchronization therapy algorithm.Heart Rhythm. 2023; 20: 1289-1296Summary Full Text Full Text PDF PubMed Scopus (1) Google Scholar We would like to know how the investigators determined the position of their left ventricular pacing leads for an effective adaptive CRT response. Alternatively, the investigators could have had the option of using multipolar leads, such as quadripolar leads, which do not require optimal lead positioning. Quadripolar leads are known to be associated with lower all-cause mortality than conventional bipolar leads.5Behar JM Bostock J Zhu Li AP et al.Cardiac resynchronization therapy delivered via a multipolar left ventricular lead is associated with reduced mortality and elimination of phrenic nerve stimulation: long-term follow-up from a multicenter registry.J Cardiovasc Electrophysiol. 2015; 26: 540-546Crossref PubMed Scopus (87) Google Scholar We declare no competing interests. Clinical outcomes of the AdaptResponse trial – Authors' replyWe thank Kazuo Komamura and Mitsunori Iwase for their interest in our study.1 We agree that the reasons for no significant difference between treatment arms in the primary endpoint are multifactorial, but this is more likely to be due to other factors besides premature study exits and low use of guideline-recommended heart failure medications. The low event rates in both treatment arms, with an overall mortality rate of 16·5% at 5 years, is important to note. This event rate is lower than previous cardiac resynchronisation therapy (CRT) trials and, in our opinion, was probably the main reason for the non-significant findings. Full-Text PDF