CRT holds promise for atrial fibrillation in heart failure

Medical Tribune April 2009 P9
David Brill

The benefits of cardiac resynchronization therapy (CRT) for heart failure could extend to those sicker patients who have atrial fibrillation (AF), according to a leading Hong Kong cardiologist.

Although more randomized controlled studies are needed, observational data so far appear to support the use of CRT for these patients said Dr. Jeffrey WH Fung, director of cardiac electrophysiology and pacing services at the Prince of Wales Hospital, Chinese University of Hong Kong.

Fung estimated that up to 30 percent of heart failure patients have AF, but noted that guidelines currently exclude this group from the class I indications for CRT. This top-level recommendation is presently reserved for those who are in sinus rhythm, while AF patients are grouped under class IIa indications – reflecting a lower level of evidence in support of the treatment.

Fung, however, pointed to a recent paper from the Multicentre Longitudinal Observational Study (MILOS) group – the largest study so far to address the use of CRT in AF patients. After a median of 34 months following CRT, all-cause and cardiac mortality were similar between the 243 AF patients and the 1,042 sinus rhythm patients. [Eur Heart J 2008 Jul;29(13):1644-52]

Further support for these findings comes from a meta-analysis of 5 observational studies involving 1,164 patients, which showed that AF and sinus rhythm patients had similar mortality 1 year after CRT initiation. Improvements in New York Heart Association functional class were also comparable for the two groups. [J Am Coll Cardiol 2008 Oct 7;52(15):1239-46]

“It seems that sinus rhythm and AF patients behave similarly after receiving CRT,” Fung summarized. He noted that sinus rhythm patients appear to fare better on quality of life measurements, but said that this finding is “consistent with other heart failure studies which show that AF patients are much sicker than those who remain in sinus rhythm, no matter what therapies they receive.”

Besides the clinical benefits, CRT also seems to offer comparable improvements between the two patient groups when it comes to echocardiographic parameters, he added.

The jury is still out, however, on whether AF patients should undergo atrio-ventricular junction (AVJ) ablation alongside CRT, said Fung. The MILOS study found that ablation improved survival compared to CRT alone but other studies have produced inconsistent results, he said, cautioning that AVJ ablation renders patients device-dependent for the rest of their lives and should not be done unless necessary.

“I think we need a properly randomized study to try to ascertain the merits of ablation or pharmacological rate control and understand which one is really preferred in patients with heart failure and permanent AF,” he said.

“We should try to maximize drugs and sometimes maybe if there is a very low percentage of pacing you may ask the patient to undergo AVJ ablation. But looking in our database it seems that most of the patients are doing fine with more than 90 percent pacing just with drugs,” he concluded.