Underlying heart disease and use of angiotensin-converting enzyme (ACE) inhibitors were found to be significant predictors of response to cardiac resynchronization therapy (CRT) upgrade in patients with chronic right ventricular pacing (RVP), according to a study published in Clinical Research in Cardiology.

In this study, 114 patients (mean age, 72.5 years; 77.2% men) with symptomatic heart failure and reduced left ventricular ejection fraction who had received a CRT upgrade in the previous 3 to 6 months due to frequent RVP (>50%) and were enrolled. In this cohort, the mean New York Heart Association (NYHA) class was 2.93 before implantation, and 78.1% of patients were NYHA class III. Improvement in NYHA class referring to the Minnesota Living With Heart Failure Questionnaire indicated response to CRT.

A linear regression model indicated that cardiomyopathy type and use of ACE inhibitors were the only factors to have an impact on the response to CRT upgrade. Patients with nonischemic cardiomyopathy (NICM) vs ischemic cardiomyopathy (ICM) had a greater responder rate (80.4 vs 60.3%, respectively, P <.05). In a univariate analysis, older age and elevated creatinine and potassium levels were associated with worse outcomes.

Continue Reading

Study limitations include the fact that the definition of CRT response was solely based on clinical improvement on the validated Heart Failure Questionnaire, and may have been overestimated owing to the placebo effect. Also, the addition of solid echocardiographic parameters to the definition of response would have yielded further information on the effect of CRT.

“Response prediction in [patients receiving] CRT upgrade due to frequent or permanent RVP remains difficult,” noted the researchers. “Only type of underlying cardiomyopathy and use of ACE inhibitor had a significant influence on CRT response with a favorable outcome of NICM compared [with] ICM. Other traditional factors in the novo CRT population like female gender or QRS width do not appear to apply to [patients with] RVP. Especially the 200-ms threshold for inclusion of chronic paced patients in past CRT trials should be reconsidered. As long as the RVP is above 50%, the exact pacing burden does not seem to have a significant effect on CRT response. An exact cut-off value for CRT upgrade response needs still to be determined.”


Rath B, Willy K, Wolfes J, et al. Predictors of response to cardiac resynchronization therapy in patients with chronic right ventricular pacing [published online December 15, 2020]. Clin Res Cardiol. doi: 10.1007/s00392-020-01785-9