Whom should I refer in 2014 for cardiac resynchronization?

Area of Science:

• Cardiology
• Medical Technology
• Heart Failure Management

Background:

• Heart failure (HF) remains a major cause of illness and death in Canada, with many patients symptomatic despite optimal medical treatment.
• Cardiac resynchronization therapy (CRT) is effective for drug-refractory systolic heart failure patients with dyssynchronous conduction, reducing hospitalizations and mortality.
• Despite CRT's benefits, approximately 30% of patients do not respond, highlighting the need for improved patient selection criteria.

Purpose of the Study:

• To review clinical predictors of response to cardiac resynchronization therapy (CRT).
• To discuss the implications of current guidelines regarding CRT candidacy.
• To identify patient populations historically underrepresented in CRT trials.

Main Methods:

• Review of clinical predictors associated with CRT response.
• Analysis of guideline recommendations based on trial evidence.
• Identification of patient subgroups with historically poor CRT response.

Main Results:

• Left bundle branch block (LBBB) and QRS duration > 150 ms are strong predictors of CRT response, supporting guideline recommendations.
• Patients with New York Heart Association (NYHA) class II heart failure are now eligible for CRT, partly due to findings from the RAFT trial.
• Atrial fibrillation, non-LBBB conduction, and chronic right ventricular pacing are associated with poor CRT response but are underrepresented in major trials.

Conclusions:

• While CRT offers significant benefits for selected heart failure patients, a substantial non-responder rate persists.
• Current guidelines strongly recommend CRT for patients with LBBB and wide QRS, expanding eligibility to NYHA class II.
• Further research is crucial to optimize CRT use in underrepresented populations, such as those with atrial fibrillation or non-LBBB conduction patterns, to improve outcomes and refine treatment recommendations.