CRT found superior to right ventricular apical pacing in patients with permanent AF

Issue: June 2011

Heart Rhythm Society 32nd Annual Scientific Sessions

Patients with permanent atrial fibrillation who, on top of atrioventricular junction ablation, were treated with cardiac resynchronization therapy had lower rates of worsening HF and hospitalizations for HF compared with those treated with right ventricular apical pacing, according to new data presented at the Heart Rhythm Society’s 32nd Annual Scientific Sessions.

According to Michele Brignole, MD, the study’s primary investigator andhead of the department of cardiology, Ospedali del Tigullio, Lavagna, Italy, the prospective study began as an attempt to add to the current level of understanding of right ventricular apical pacing vs. cardiac resynchronization therapy (CRT) in patients with AF, which he said only consisted of a few small short-term trials.

“So there is a lack of knowledge,” Brignole told Cardiology Today. “For this reason, current guidelines in America (2008) and Europe (2010) on CRT have ranked CRT pacing as Class IIa level of evidence B and only for a subgroup of patients with AF, specifically the subgroup of patients with large QRS, low ejection fraction and NYHA Class 4.”

To bring further clarification to this issue on a larger scale, Brignole and fellow researchers randomly assigned 186 patients from 19 hospitals to receive either optimized echo-guided CRT (n=97) or right ventricular apical pacing (n=89). All patients had previous atrioventricular junction and CRT implantation performed successfully. The study’s primary endpoint was a composite of death from HF, hospitalization due to HF or worsening HF.

During a median follow-up of 20 months, the primary endpoint proved to be significantly lower in the CRT group vs. those in the right ventricular group (11% vs. 26%; sub-HR=0.37; 95% CI, 0.18-0.73). This was due primarily to significantly lower rates of worsening HF (sub-HR=0.27; 95% CI, 0.12-0.58) and hospitalizations for HF (sub-HR=0.20; 95% CI, 0.06-0.72) in the CRT group because the rates of mortality between groups were similar. As a result, the CRT mode was an independent predictor of the absence of clinical failure (OR=0.19; 95% CI, 0.05-0.67).

For Brignole, two important implications can be taken from this trial. “The first is that this trial confirms the Class IIa indication of the most recent guidelines,” he said. “This indication was mainly based on an expert consensus opinion, rather than based on real studies. This is the first study that gives evidence of clinical benefit of therapy in patients who already have a IIa indication. In other words, this study could serve to upgrade the current recommendation from IIA to Class I.”

The second implication, however, according to Brignole, is even more important. “This study, if confirmed by others, would expand the indication of guidelines to all patients with severe symptomatic AF, independently for ejection fraction, length and duration of QRS and so on,” he said, but adding that this study must be regarded as somewhat preliminary. – by Brian Ellis

For more information:

Brignole M. LB-05. Presented at: Heart Rhythm Society 32nd Annual Scientific Sessions; May 4-7, 2011; San Francisco.

This is an interesting study, but the results must be interpreted cautiously because CRT was compared to RV apical pacing. The latter is known to be potentially detrimental so the positive results in the CRT arm can reflect avoidance of harm from RV apical pacing, as well as the benefits from CRT pacing. Further, patients had AV junctional ablation to facilitate pacemaker capture. The "pure" study would demonstrate the benefits of CRT in AF patients without junctional ablation compared to similar AF patients not receiving CRT.

– Douglas Zipes, MD
Cardiology Today Section Editor

Disclosure: Drs. Brignole and Zipes report no relevant financial disclosures.

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