Coronary artery disease
Predictors of Lack of Response to Resynchronization Therapy

https://doi.org/10.1016/j.amjcard.2005.02.009Get rights and content

About 30% of patients treated with cardiac resynchronization therapy (CRT) do not respond to treatment. The aim of this study was to identify clinical predictors of lack of improvement in patients receiving CRT. From 197 consecutive patients scheduled to receive CRT, 143 fulfilled the inclusion criteria. Mean age was 68 ± 7 years and 79% were men. Heart failure was due to ischemic heart disease in 49 patients (34%). Mean QRS duration was 165 ± 26 ms, and left ventricular ejection fraction was 27 ± 7%. Nonresponder patients were defined as those who died of heart failure, underwent heart transplantation, or did not increase the distance walked in 6 minutes >10%. At 6-month follow-up, there were 28 nonresponders (20%). Among nonresponders, 2 patients received a heart transplantation and 9 patients died of heart failure. In logistic regression analysis, independent predictors of lack of response to CRT were ischemic heart disease (odds ratio [OR] 2.9, 95% confidence interval [CI] 1.2 to 7; p = 0.023), severe mitral regurgitation (OR 3.5, 95% CI 1.3 to 9; p = 0.014), and left ventricular end-diastolic diameter ≥75 mm (OR 3.1, 95% CI 1.1 to 8; p = 0.026). Patients with these 3 predictors had a probability response of 27%.

Section snippets

Study design

This observational, longitudinal study involved 6 centers in Spain. Enrollment began in January 2001, and patients were included consecutively. Follow-up examinations were scheduled for 6 months.

LV pacing leads were implanted transvenously through the coronary sinus, and whenever possible, in a lateral branch. In patients with sinus rhythm, the optimal atrioventricular (AV) delay was determined with pulse-wave Doppler of the LV inflow, selecting the AV delay that produced the longest LV filling

Study population

Between January 2001 and January 2003, 197 consecutive patients were scheduled to receive CRT. Twenty patients were excluded from the study because they did not undergo a baseline 6-minute walk test despite not being in NYHA functional class IV. In the remaining 177 patients, endocardial stimulation from the coronary sinus was acutely unsuccessful in 20 patients (11.3%). In 10 additional patients, pacing was only achieved at the anterior vein, in a septal position, and they were also excluded

Discussion

The major finding of the present study is the identification of simple, clinical, and echocardiographic preimplantation parameters that are able to predict a lower probability of clinical improvement with CRT in patients with heart failure and intraventricular conduction delay.

Previous multicenter studies such as the Pacing Therapies in Congestive Heart Failure (PATH-CHF),5 Multicenter InSync Randomized Clinical Evaluation,4 MUltisite STimulation In Cardiomyopathies,10 and Comparison of Medical

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Dr. Díaz-Infante was supported by a grant from Sociedad Española de Cardiología, Madrid, Spain. Investigator meetings were supported by a grant from Guidant Corporation, Madrid, Spain.

Participating investigators and study centers of the Spanish Cardiac Resynchronisation Study (SCARS) are listed in the Appendix.

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