Wednesday, November 01, 2006
Heart Failure: Why Wait Until Extremes?
Today's New England Journal of Medicine disclosed the effectiveness of a left ventricular assist device (LVAD) and medical regimen at reverse-remodeling chronically dilated hearts back to near-normal in a small subset of 15 patients. While these data were novel and encouraging - one wonders if these individuals could have been spared the need for left-ventricular assist devices if they had had implementation of biventricular pacing earlier in their clinical course.
I was unable to find mention of the EKG duration of the patients followed in the New England Journal of Medicine article, nor did it appear that ANY of these patients had received a biventricular pacing device. I suppose I should not be surprised, since the New England Journal of Medicine study was funded by the LVAD manufacturer, Thoratec. But excluding this data omits important data regarding these severe heart failure patients: was all done for these patients before LVAD implantation? Although I appreciate that not all heart failure can be detected early, 12 of 15 of the patients in this study had been treated for at least 6 months before LVAD implantation without biventricular pacing, leading me to wonder if the implantation of a biventricular device could have prevented the need for the LVAD.
Biventricular pacing has now been firmly established as an effective means of treating patients with severe congestive heart failure on maximal medical therapy. It should probably be considered the standard of care, in my view, for patients with severe cardiomyopathy refractory to medical therapy with evidence of conduction delay during activation of the left ventricle (QRS duration >=120 msec). Biventricular pacing involves placing a left ventricular pacing lead in addition to a right ventricular pacing lead to re-coordinate the pumping action of the ventricular pumping chambers. Clinical studies have demonstrated that approximately 2/3rds of symptomatic patients have an improvement in their 6-minute hall walk test (walking on average an additional 50 meters), improve by about one New Heart Association heart failure class, and have improved quality of life using self-assessment measures. More importantly, the COMPANION and recently-released CARE-HF trials have demonstrated a mortality benefit to patients receiving biventricular pacing devices. Anecdotally, I have seen complete normalization of left ventricular function in a small subset of patients with non-ischemic cardiomyopathy (like those the the NEJM article) after this therapy has been deployed.
It should be noted that the effect of biventricular pacing trials has been so impressive that earlier intervention of biventricular pacing in heart failure is now being evaluated in the BLOCK-HF trial and its application to patients with normal EKG duration in St. Jude Medical's RethinQ trial.
Hopefully we'll remember the benefit of biventricular pacing therapy (with or without an implantable defibrillator) in our sickest heart failure patients and apply this before the need for an LVAD arises.