May 12th, 2013

How Should Recent Trials Affect CRT Practice?


In recent weeks the cardiac resynchronization therapy (CRT) field has been absorbing the publication of the BLOCK HF trial in the New England Journal of Medicine and the publication of the NARROW-CRT trial in Circulation: Arrhythmia and Electrophysiology. These trials raised the possibility that CRT may improve clinical status in some patients with ischemic cardiomyopathy and narrow QRS. At the same time, however, news emerged that the EchoCRT trial, which was looking at CRT in HF patients with QRS <130 msec, had been stopped due to futility. CardioExchange’s John Ryan asked Duke’s Sana Al-Khatib to answer questions about these developments.

Ryan: Are the data from BLOCK HF sufficient to change your practice? In patients with AV block and decreased EF, are you going to be recommend CRT placement? Or have you been doing so already?

Al-Khatib: BLOCK-HF was a well-designed and conducted trial. In general, we require more than one good trial to change practice; however, given these data from BLOCK-HF and the convincing data on the potential deleterious effects of right ventricular pacing from different studies, I personally think it is best to implant a biventricular device in patients who meet the entry criteria of the BLOCK-HF trial. We have not been implanting a CRT device in such patients. I expect the results of BLOCK-HF to change practice.

Ryan: Why are there discrepant results in CRT on patients with narrow QRS? What is your opinion on the effects of CRT in HF patients with narrow QRS?

Al-Khatib: I have concerns about the NARROW-CRT trial that range from the relatively small sample size, to the integrity of blinding, to the methodology they used to determine dyssynchrony. When the EchoCRT trial was stopped due to futility, my understanding is that the trial had a much larger number of patients than the patients enrolled in NARROW-CRT (close to or more than 1000 patients in Echo CRT compared with only 111 patients in NARROW CRT). Although the results have not been published, and I cannot give my final assessment of EchoCRT until I see the data, I have to infer, based on the resources and expertise invested in EchoCRT, that CRT is not likely at all to be beneficial in patients with a narrow QRS. Therefore, we, as a medical community, should focus our efforts on other patient populations.



2 Responses to “How Should Recent Trials Affect CRT Practice?”

  1. Jean-Pierre Usdin, MD says:

    May be an explanation can be the difference between the indication for the pace maker:
    In Echo RCT the option was: “does this patient need a pace maker?”
    In BLOCK HF the patient definitely needs a pace maker (ancillary indication of this device…) the pace maker is a necessity, during the same procedure it seems logical to give the patient the best option (but consider rate of complication is 6.4% , with practice it will decrease)
    Seniors as I am will, sure remember, the same kind of discussion when it was the beginning of Dual-chamber pacemakers in the middle of 70’s.

  2. H Robert Silverstein, MD says:

    Clearly the uniform swirl of ventricular contraction is an ideal and should be pursued whether by revascularization or pacing or whatever else is to come. Conclusions should not be drawn prematurely when a study does not work out beneficially YET, such as pacing in a narrow QRS circumstance. Almost certainly techniques will be developed, skills honed, and “visualization” of the myocardium will improve. Moreover, benefits (and problems) may not be seen within the scope of 5 and 10 year studies. My prediction is that strain,strain rate, and speckle tracking or MRI wall motion recordings will show us when and where to pace and in whom, it is just a matter of willingness and time ….