Are ICDs overused?

The medical news of the week nearly shocked me off my bike trainer.  It isn’t often that electrophysiology makes the major-network evening news broadcast.

The teaser proclaimed…“thousands of heart patients have unnecessary expensive cardiac devices…Should they be removed?”

They were talking about ICDs (internal cardiac defibrillators), and were referring to the widely publicized JAMA study that reported one in five (25000) ICDs implanted between 2006-2009 were outside of evidenced-based guidelines.

I am a real doctor so let’s start with a real story:

Mr [Smith], a jovial pot-bellied farmer, was in to see me recently.  His demeanor is one that exudes life.  His story is as epic as the warmth of his smile.  It’s the kind of story that sticks with you—human stories always resonate more than paired-t-tests.

About a year ago, the text message form the pacemaker nurse read: Mr [Smith] called this morning because he was shocked at 4 AM.  His transmission showed VF [VF is ventricular fibrillation–translation: sudden death.]

My response:  Can he come in now, I have a case in the EP lab soon.

A few minutes later this response came:  No. He just sat down at Denny’s with his wife.  He said he can come in after that…He feels fine.

Herein lies the problem with calling non-evidenced-based ICDs ‘inappropriate.’  Statistics are one thing, Mr Smith’s eventful morning was yet another. He was enjoying a Grand-slam breakfast with his wife, but if not for that ICD, he would have been in the funeral home.

When Mr Smith finally made his way to the office, I learned some interesting things about his past history.  I had implanted his ICD prophylactically almost a year ago.  The reasons were that he had a low-ejection fraction (weak heart) and a previous heart attack.  But here is the kicker: on one of the pre-ICD imaging studies the strength of his heart–measured by the ejection-fraction (EF)–was estimated at 38%, however, 35% is the upper-limit for placing an ICD.  Alas, his life-saving shock was delivered by a non-evidenced-based ICD!

Why would I have deviated from the guidelines?

Perhaps because of my 15 year experience base, or that the notches in Mr Smith’s resting ECG whispered ventricular tachycardia to me, or because I know that one echo-interpreters EF of 38% is another’s 33%. These vagaries are doctoring–in the real-world.

Enough storytelling, let’s get back to the study.

So why are doctors erring on the side of implanting more ICDs than statistical outcomes researchers say they should?

For the moment, let’s assume the statisticians are right; there are too many ICD implants.  Here are four possible explanations:

• Mr Smith’s story illustrates the primary reason.  ICDs are not used to treat a malady, they are used to prevent death.  In the culture of heart doctors, death is failure, and heart doctors despise failure.
• Most heart doctors don’t live with a palliative care specialist who tells stories of human suffering that makes the painless death from a malignant arrhythmia seem like a blessing.  Thus, they may not realize the importance of discussing end-of-life wishes with the patient before ICD surgery. (And they sure aren’t paid for their time to do so.)
• Heart doctors are optimists.  They seem to purge negative ICD data from their minds. How many heart failure patients considered for an ICD hear about the “sobering” 168-day median survival after an appropriate ICD shock? (As published in the NEJM in 2008.) How many patients understand that an ICD–unlike an insurance policy– has substantial risks, including infection, painful shocks and manufacture recalls?
• The cynics would say that ICDs are overused because they are easy to implant and well compensated.  That would be true, especially when one compares the ease of a thirty minute ICD implant with the angst of a thirty minute office visit to explain that a dad or mom has a terrible heart and won’t benefit from an ICD.  (That said, ICD surgery is not like spinal fusions; ICD implanters aren’t getting million dollar royalties from medical device makers.  At least none that I know are.)

Now let’s insert five real-world notions into the analysis of the ICD debate and science of this study.

• The ICD registry data likely over represents the number of inappropriate ICDs.  For example, thirty percent of the ICDs were deemed inappropriate because of a heart attack in the past 40 days.  But how many of these hart attacks were ‘enzyme rises’ that were called heart attacks, or were minor heart attacks in a patient who previously qualified for an ICD based on a remote heart attack years ago?
• Not all ICD implants neatly fall into guidelines.  For instance, what about the patient who presents with newly discovered heart block who may theoretically benefit from an ICD.  Would you do place a pacemaker knowing there was a good chance of needing an ICD later?
• Indications for ICDs are misclassified. At least in my experience, ICDs implanted because of symptoms (secondary prevention) are frequently misclassified as prophylactic. ICD registry data is submitted by a retrospective review of charts by chart-reviewers not clinicians. These are not prospective trials.
• More than half of the questioned ICD implants were in patients with newly diagnosed heart failure. Although it sounds Clinton-esque to ask, “How new is new,” concerns about timing of ICD implants are not insignificant.  Even experts aren’t sure about how long after the initial diagnosis one should wait before implanting an ICD.  These words are from the 2008 ACC/AHA/HRS ICD guidelines…

...The optimal time required for this assessment is uncertain; however, another analysis determined that patients with non-ischemic DCM (Ed note: DCM means dilated cardiomyopathy or a weak heart) experienced equivalent occurrences of treated and potentially lethal arrhythmias irrespective of diagnosis duration. These findings suggest that use of a time qualifier relative to the time since diagnosis of a non-ischemic DCM may not reliably discriminate patients at high risk for SCD in this selected population. Given these considerations, physicians should consider the timing of defibrillator implantation carefully.

• Although there were modest increases in in-hospital complications (3.2% vs 2.4%) for non-evidenced-based ICDs, the study does not report on what really matters: what were the long-term outcomes of the two groups?  Did the non-evidenced-based group fare worse at one or two years?

In summary, this is an important trial that sheds light on an important topic.  ICDs are serious.  In selecting patients for ICDs, we can do better. We should do better.

But now I fear that the pendulum is swinging.  It’s a heavy wide pendulum that is sure to hurt when it hits. It always hurts when statistical spreadsheets and over-reaching arbitrary guidelines bully themselves into the doctor-patient relationship.

Mr [Smith] is sure glad that his care came from a doctor, not a pdf file.

JMM