Clinical Long-Term Response to Cardiac Resynchronization Therapy Is Independent of Persisting Echocardiographic
Barbara Naegeli1, Hans-Peter Brunner-La Rocca2, Christine Attenhofer Jost1
1HerzGefassZentrum, Klinik Im Park, Seestrasse 247, CH-8027 Zurich, Switzerland.
Insights
Correction of cardiac dyssynchrony after cardiac resynchronization therapy (CRT) is not required for favorable long-term outcomes. Even with persistent dyssynchrony, patients showed similar clinical responses, suggesting CRT effectiveness is independent of echocardiographic parameter correction.
Area of Science:
- Cardiology
- Medical Technology
Background:
- Cardiac resynchronization therapy (CRT) aims to improve outcomes by correcting cardiac dyssynchrony.
- It was hypothesized that correcting dyssynchrony is crucial for long-term patient response to CRT.
Purpose of the Study:
- To determine if the correction of dyssynchrony parameters after CRT implantation is a prerequisite for favorable long-term outcomes.
- To evaluate if persistent dyssynchrony predicts a less favorable response to CRT.
Main Methods:
- A cohort of 128 patients undergoing CRT implantation were followed for 27 months post-optimization.
- Long-term outcomes were assessed by a composite of cardiac mortality/heart transplantation and heart failure hospitalizations, with NYHA class as a secondary endpoint.
- Echocardiographic parameters were used to assess atrioventricular, interventricular, and intraventricular dyssynchrony post-CRT.
Main Results:
- A clinical response to CRT was observed in 76% of patients, with significant improvement in NYHA class (P < 0.001).
- Despite optimization, residual dyssynchrony was present in a notable percentage of patients (AV: 7.2%, VV: 13.3%, IV: 16.4%).
- Crucially, persistent dyssynchrony did not significantly impact the combined primary and secondary endpoints compared to patients without mechanical dyssynchrony.
Conclusions:
- Successful CRT implantation leads to favorable long-term clinical outcomes irrespective of the complete correction of echocardiographic dyssynchrony parameters.
- QRS width during biventricular stimulation did not differentiate between responders and non-responders.
- These findings suggest that CRT efficacy may not solely depend on achieving specific echocardiographic targets for dyssynchrony correction.
Background:
The aim of the study was to prove the concept that correction of established parameters of dyssynchrony is a requirement for favorable long-term outcome in patients with cardiac resynchronization therapy (CRT), whereas patients with persisting dyssynchrony should have a less favorable response.
Methods:
After CRT implantation and optimization of dyssynchrony parameters, we evaluated whether correction or persistence of dyssynchrony predicted long-term outcome. Primary endpoint was a combination of cardiac mortality/heart transplantation and hospitalization due to worsening heart failure, and secondary endpoint was NYHA class.
Results:
One hundred twenty-eight consecutive patients (mean age 68 ± 10 years) undergoing CRT with a mean left ventricular ejection fraction of 27±9% were followed for 27 ± 19 months. All cause mortality was 17.2%, cardiac mortality was 7.8% and 3.1% had to undergo heart transplantation. Rehospitalization due to worsening heart failure was observed in 14.8%. NYHA class before CRT implantation was 2.8 ± 0.8 and improved during follow-up to 2.0 ± 0.8 (P < 0.001). A clinical response was observed in 76% (n = 97) and an echocardiographic response was documented in 66% (n = 85). After individually optimized AV and VV intervals with echocardiography, atrioventricular dyssynchrony was still present in 7.2%, interventricular dyssynchrony in 13.3% and intraventricular dyssynchrony in 16.4%. Despite persistent atrioventricular, interventricular and intraventricular dyssynchrony at long-term follow-up, the combined primary and secondary endpoints did not differ compared to the group without mechanical dyssynchrony (P = ns). QRS duration with biventricular stimulation did not differ between responders vs. nonresponders.
Conclusion:
After successful CRT implantation, clinical long-term response is independent of correction of dyssynchrony measured by echocardiographic parameters and QRS width.
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