Real-world thoughts on the life RAFT

This year’s American Heart Association (AHA) meeting is brimming with news.

Since the WSJ had ICD devices in its corporate news section today, it seems a good place to start.

Here is the summary: (The short version)

According to the RAFT study, patients who are ICD candidates, and have a left bundle branch block fare better (lower mortality and less heart failure) with a three-lead (CRT = Cardiac Resynchronization Device) ICD versus the standard one or two lead ICD system.

These CRT devices, by virtue of a third lead placed over the left ventricle, cause the ailing heart to beat synchronously. Previous trials have shown that three-lead ICD systems (compared to conventional ICDs) improve heart function and prevent episodes of congestive heart failure, but this trial is the first to show that the more complex ICD improves longevity.

For the record: This is a CRT-pacemeker

Moreover, statistics are nice, but few triumphs in heart rhythm management come close to the joy of bearing witness to the Lazarus-like phenomenon of the CRT “super-responder” three months after implant. In selected patients these devices rock.

Clinicians have known this for years, but now, the RAFT trial provides even more scientific data to support the benefit of CRT devices.

Some words of caution though:

In RAFT, CRT devices were nearly two-fold more likely to be associated with procedure-related complications. This makes sense because they are far more challenging to implant.

Also, on the same day that this highly publicized “positive” trial is released, a sobering report on who doesn’t benefit from CRT is also released—to much less fanfare.  Using the Medicare ICD registry, Charlottesville, VA researchers analyzed 14,946 patients who had a CRT implanted in 2005-2006. There were 4 predictors of a poor outcome after CRT implants. Those patients with right (not left) bundle branch block, ischemic heart disease (large scar burden), Class IV Heart failure (end-stage disease) and advanced age fared poorly after having CRT devices.

Why?

  1. Advanced-age patients die of other causes. CRT devices can only improve longevity if heart disease is the primary limiter of survival. Older patients often have other diseases which limit their survival. 
  2. Class IV Heart failure is medical-speak for heart muscle weakness so advanced that no pacemaker will help make the heart muscle squeeze any better. Hence these patients garner no benefit from any amount of pacing leads.
  3. Ischemic cardiomyopathy means that the heart has been weakened by an old heart attack. Scar has replaced muscle, and scar doesn’t contract. It has long been known to installers of these devices that patients with large scar burdens are poor responders to three-lead ICDs. 
  4. Finally, a medical student can tell the difference between right and left bundle branch block. For years, realists knew that RBBB patients do not respond to CRT. (Simply because RBBB patients have normal septal contraction patterns; RBBB does not cause dyscynchrony.)

That said, in present-day real-life clinical practice, patients with LBBB, weak hearts and accompanying cardiac symptoms are–for the most part–receiving CRT devices. One person’s ‘mild’ class-II heart failure symptoms is another’s ‘moderate to severe’ class III-symptoms–especially when the doctor knows that a CRT device is best for the patient. Thus, I don’t think the regulators (of expensive therapies) should worry too much about Dr William Abraham’s comment to the WSJ that RAFT will “open the floodgates” of CRT device implants.

And, as is the case, always, in the treatment of established heart disease, we are advancing nicely.  New drugs like dabigatran, new procedural advances in catheter ablation, and now life-advancing and life-enhancing cardiac devices are continued illustrations of the benefits of the ‘fury’ of modern medical practice.

If only we could harness some of this fury in the “primary” prevention of heart disease. That would be progress.

JMM

References:
RAFT Trial:  http://www.nejm.org/doi/pdf/10.1056/NEJMoa1009540
MADIT-CRT Trial: http://www.nejm.org/doi/pdf/10.1056/NEJMoa0906431
Bundle Branch Morphology…other predictors of outcome in CRT: http://circ.ahajournals.org/cgi/content/abstract/122/20/2022?view=short&fp=2022&vol=122&lookupType=volpage

2 comments

  1. ICD is Internal Cardiac Defibrillator
    CRT is Cardiac Resynchronization Therapy = BiV device.

    CRTs come as 3 lead pacemakers or 3 lead ICDs. In the above post, the CRT devices are CRT-Ds (3 lead ICDs).

    JMM

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