Part 1 of my favorite ICD-related stories from HRS 2012

May 25, 2012 07:55 EDT

Let's talk about implantable cardiac defibrillators (ICDs). It's a really hard topic. Afford me some leeway, please.

First, my disclosures

I implant ICDs. My dear friend and neighbor Hans lived six years after he received a life-saving shock from a device I implanted. I am an ICD believer. On the other hand, I see the other side: inappropriate shocks, serious infections, and misuse. One more thing: I am married to a hospice doctor, and we talk frequently about end-of-life decision making.

I am not a neutral discussant. 

Introduction

The exact role of the ICD has always engendered discussion, but now the debate is really on. Therapeutic nihilists argue that ICD proponents underestimate risks and overemphasize benefits. Get-with-the-Guidelines people make the case that ICDs are underused. Our current Heart Rhythm Society (HRS) president, Dr Bruce Wilkoff, recently (AHA 2011) took the protagonist stand that ICDs should be used as a quality measure for heart failure. That kind of boldness draws fire from journalists—who point out that the HRS enjoys huge financial support from ICD makers.  

While heart doctors debate the exact role of ICDs, experts in end-of-life care talk about an often downplayed risk: that painful shock(s) may simply change the mode of death—from sudden and painless to not. They point to sobering studies, like one in the New England Journal of Medicine, that illustrate the concept that shocks due to ventricular arrhythmia often portend death. In this SCD-HeFT cohort, median survival in patients with appropriate shocks was only 162 days. From the vantage point of a doctor comfortable with the notion of our finite mortality, ventricular fibrillation offers something valuable—a peaceful death.

Doctors are not the only group with consternation about ICDs. The US government has injected itself in the debate. As stated by Dr Suneet Mittal at HRS 2012: "This is first time in the history of US medicine that a national coverage decision is being nationally enforced." And is it ever! Scrutiny from the ever-powerful Department of Justice (DoJ) has had a chilling effect on ICD implants. Electrophysiologist and journalist Dr Jay Schloss offers this concise review (on CardioBrief) of one hospital's experience with a DoJ audit.

See . . . I warned you. ICDs engender controversy.

With the inflammation behind us, let's run through part 1 of my list of notable ICD-related abstracts and presentations from HRS 2012.

What happens to patients implanted with non–evidence-based ICDs?

The current debate about ICDs centers mostly on timing violations. Dr Al-Khatib's now famous JAMA paper reported that 22% of primary-prevention ICDs fell outside of the evidence base—mainly because they were implanted within 40 days of an MI or within 90 days of revascularization or a new diagnosis of CHF. The Centers for Disease Control and Prevention (CDC) audits and DoJ investigations of ICDs are focusing primarily on these timing issues. Although the JAMA paper reported patients with non–evidence-based ICDs had slightly more in-patient complications, the question remains on how well they do in the long-term.

That's why I loved this abstract from the 3000-patient strong OMNI Registry of cardiac device patients. Researchers focused on 590 of 1412 ICD patients that had primary prevention implants. They found one in 10 implants was done outside of an evidence-based indication. But . . . here's the kicker: Non–evidence-based patients had the same time to appropriate shock, risk of death, or time to inappropriate shock. These findings are quite provocative; they suggest patients implanted outside of the current evidence base experienced similar therapeutic outcomes and benefits. And to me, this strengthens the argument against equating "non–evidence-based" with "inappropriate."

Not surprisingly, the Heart Rhythm Society featured this study as an important contribution. Quoting from its release:

HRS has openly emphasized—as did the JAMA article—that the ultimate judgment of the care of a particular patient must be made by the physician and the patient in light of all of the circumstances presented by the patient. There are circumstances in which deviations from these guidelines are appropriate.

 If only such wiggle room existed these days.

Baseline burden of heart failure limits benefit from an ICD

It's well established that ICDs lower mortality in carefully selected patients with heart failure and low ejection fraction. Less well-known is the time dependence of this benefit. To realize a mortality advantage from the ICD, heart-failure patients must live more than 18 months after the implant. Remember, the Kaplan-Meier curves from SCD-HeFT do not separate until after 18 months.

Here's an abstract highlighting the impact of preimplant heart-failure burden on survival after an ICD implant:

Linking data from a CMS ICD registry and Medicare files, a group of researchers from Harvard and Duke, including well-known heart-failure expert Dr Lynne Warner Stevenson, identified 66 974 patients who underwent ICDs for primary prevention. Patients were separated into four groups based on heart-failure burden. More than 50% of patients with the highest burden of heart failure died in 1.5 years, which the authors point out, would be too soon to benefit from an ICD. They conclude that the underlying burden of CHF should be considered when assessing the benefits of an ICD.

These findings reinforce the importance of bracketing patients most likely to benefit from an ICD. Other authors have suggested applying a simple five-point clinical risk score (age, BUN, QRS duration, NYHA class, and AF) to stratify ICD candidates. Doing so reveals a U-shaped pattern of ICD efficacy: those with intermediate risk benefit, while those at low or very high risk scores do not.

The message: Realizing the benefits of ICD therapy requires applying the device to carefully selected patients. Do not overtreat patients burdened with competing causes of death, including significant heart failure.

An amazing summary of ICD clinical trials

One of the most cogent presentations I have heard on primary-prevention ICDs is available for free at the Heart Rhythm Society website. When you have 20 minutes (I know, that's a long time), it's worth listening to noted expert Dr Andrew Epstein, from the University of Pennsylvania, run through the data behind timing restrictions of ICDs. He's a great speaker, and he gives a very fair and balanced assessment of the clinical trials supporting current ICD guidelines.

This concludes part 1. Look for part 2 of my favorite ICD abstracts coming soon.

JMM