Both CABG, CRT Indicated? Same-Session Surgery, Implantation Best, Study Finds

June 03, 2010

June 3, 2010 (Berlin, Germany) — If a patient with systolic heart failure and signs of ventricular dyssynchrony is undergoing CABG, that's probably also the best time to implant a cardiac resynchronization therapy (CRT) pacemaker, a small randomized study confirmed. That way, epicardial leads--which often get better results than transvenous leads--can be positioned during the open-chest procedure. But more important, there's little to be gained and perhaps much to lose clinically by taking a "wait-and-see" approach to CRT after revascularization, according to investigators here at the Heart Failure Congress 2010 sessions of the Heart Failure Association of the European Society of Cardiology.

Dr Alexander Romanov

"In the majority of cases, CABG neither eliminates dyssynchrony nor improves left ventricular systolic function," observed Dr Alexander Romanov (Novosibirsk State Research Institute of Circulation Pathology, Russia) when presenting the study, which randomized 178 patients with drug-refractory NYHA class 3-4 heart failure, an LVEF<35%, standard indications for CABG, and evidence of ventricular dyssynchrony by any of several methods to be given or not given a CRT device with epicardial lead placement at the time of surgical revascularization.

Those who got the devices with the CABG showed significant improvements in ventricular function, NYHA status and six-minute-walk distance, and quality of life over a mean follow-up of about 18 months, with gains in many cases becoming significant after the first three months, compared with the patients who received CABG only. And their mortality, the study's primary end point, was significantly reduced (p=0.006), Romanov reported.

Prof John GF Cleland (University of Hull, Kingston-upon-Hull, UK), who wasn't involved in the study, went to Romanov right after his presentation and said, "Nice. We're going to be telling our surgeons straightaway."

Prof John GF Cleland

To heartwire , Cleland observed that some of the earliest clinical studies of ventricular dyssynchrony were conducted by surgeons who performed CABG with the goal of correcting or improving it, "so many surgeons believe that the dyssynchrony will be fixed by revascularization, and you won't need to pace." Even many cardiologists, he added, would tend to favor revascularization first, to see if it improves heart function, before considering CRT. The current study suggests that CRT shouldn't wait.

The 91 patients who underwent CABG with pacing-only CRT (CRT-P) implantation and the 87 who received CABG alone were similar at baseline with respect to QRS duration, echocardiographic features--including severity of dyssynchrony--and NYHA class, functional capacity, and quality of life. Ventricular dyssynchrony was defined according to QRS duration >120 ms, per guidelines, or by any of several echocardiographic or tissue-Doppler-imaging methods.

The CABG-only patients didn't show much change in functional or quality-of-life measures throughout the follow-up, whereas the CABG+CRT group showed marked improvement within three months and then continued improvement (compared with CABG-only patients) in NYHA class (p=0.026), six-minute-walk distance (p=0.001), LVEF (p=0.001), and scores on the Minnesota Living with Heart Failure Questionnaire (p=0.001) throughout the rest of the follow-up.

Changes in dyssynchrony, as measured by tissue-tracking imaging and by tissue-resynchronization imaging, followed a similar pattern: little change in the CABG-only group but pronounced and significant improvement in the CABG+CRT group at the three-month follow-up (p=0.0001 for both imaging methods), which continued for the rest of the trial.

Mortality reached 26.4% in the CABG-only group and only 9.9% in CABG+CRT group (p=0.006). In multivariate analysis, significant mortality predictors did not include age, sex, diabetic status, NYHA functional class, baseline LVEF or QRS duration, or baseline end-diastolic or end-systolic volumes. However, LV dyssynchrony persisting after CABG showed a mortality hazard ratio of 2.634 (95% CI 1.20–5.75; p=0.015).

Cleland noted that epicardial lead placement could well be another advantage to CRT implantation at the time of CABG. There are limited options for positioning transvenous leads, and "the cardiologist very often has a problem finding the best spot for resynchronizing the ventricle. Surgeons can choose any spot they want," he said. "I think there's still a role for epicardial-lead pacemakers--if I needed resynchronization [therapy] and a bypass, then I'd want the surgeon to do that."

Neither Romanov nor Cleland had any conflicts of interest.


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