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Updated: Jun 24, 2026
Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Identification of responders to cardiac resynchronization therapy by contractile reserve during stress
Quirino Ciampi1, Lorenza Pratali, Rodolfo Citro
1Division of Cardiology, Fatebenefratelli Hospital, Viale Principe di Napoli, Benevento, Italy. qciampi@iol.it
Insights
Contractile reserve (CR), not dyssynchrony, best predicts response to cardiac resynchronization therapy (CRT). Patients with CR showed improved clinical outcomes and reverse left ventricular remodeling after CRT.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Echocardiography
Background:
- Identifying responders to cardiac resynchronization therapy (CRT) is crucial for optimizing treatment.
- Both electrical dyssynchrony (DYS) and myocardial contractile reserve (CR) are potential indicators of CRT response.
Purpose of the Study:
- To assess the predictive value of DYS and CR in identifying patients who will respond to CRT.
- To determine if CR or DYS is a better predictor of clinical and echocardiographic response to CRT.
Main Methods:
- Sixty-nine patients with heart failure referred for CRT underwent baseline DYS and dobutamine stress echocardiography to assess CR.
- CR was defined as a wall motion score index variation >= 0.20.
- CRT responders were identified by clinical improvement or a >= 15% decrease in end-systolic volume.
Main Results:
- 66% of patients were clinical responders, and 58% showed reverse left ventricular remodeling.
- CR was significantly more prevalent in responders (78%) compared to non-responders (P=0.001).
- CR (Odds Ratio = 6.2) was the strongest predictor of CRT response, outperforming DYS.
Conclusions:
- Patients with preserved contractile reserve demonstrate a favorable response to CRT, including clinical improvement and reverse remodeling.
- The findings suggest that the myocardial substrate (CR) is a more critical determinant of CRT efficacy than electrical dyssynchrony.
Aims:
The identification of responders to cardiac resynchronization therapy (CRT) remains a challenge. We assessed the role of dyssynchrony (DYS) and contractile reserve (CR) in identifying CRT responders.
Methods And Results:
Sixty-nine patients (55% with ischaemic aetiology) referred for CRT (ejection fraction < or =35%, New York Heart Association > or =III, and QRS duration > or =120 ms) underwent baseline evaluation of DYS and dobutamine stress-echo [up to 40 microg/kg/min: CR was defined as a wall motion score index (WMSI) variation > or =0.20]. CRT responders were identified by clinical and/or echocardiographic [end-systolic volume (ESV) decrease > or =15%] follow-up criteria. During a median follow-up of 11 months, 46 patients (66%) were classified as clinical responders. Reverse remodelling was found in 34 of the 59 patients (58%) with echocardiographic follow-up. CR was present in 78% of clinical responders (P = 0.001) and in 69% with reverse remodelling (P = 0.005). DYS was equally present in the two groups. Reverse remodelling was correlated with rest-stress changes in ESV (r = 0.439, P = 0.003) and in WMSI (r = 0.450, P = 0.001), but not with DYS. CR (OR = 6.2, 95% CI = 1.4-27.6, P = 0.015) was the best predictor of response to CRT.
Conclusion:
Patients with CR show a favourable clinical and reverse LV remodelling response to CRT. This finding shifts the focus from electrical (dyssynchrony) to the myocardial substrate of functional response.
