It's ironic that I wasn't going to say much about the SIMPLE trial (A randomized trial of defibrillation testing at the time of ICD implantation: Results of the Shockless Implant Evaluation trial)[1]. I had my biases about defibrillation threshold (DFT) testing at the time of ICD implant. They were strong biases. I, John Mandrola, experienced electrophysiologist, knew what the trial would show, and I already knew when to do the test and when not to do the test.

Plus, I had liked the idea that either choice—to do a DFT or not—was okay. There are so few things in medicine these days that turn solely on clinical judgment.

Then I met up with a respected academic researcher walking into the conference. She asked me what I thought about SIMPLE. When I told her DFT testing wasn't that interesting, she got this look that I remember from training days. It was a blank look that seemed to say, why not, Mandrola, you don't think having excellent data that answer an important question is a good thing?

Something flipped in my head at that moment. I got to thinking about my thinking. Here I was, falling into the very trap that I write about: namely, the idea that I know what is best for the patient because of my eminence (small that it is) rather than the evidence. Twenty years of experience teaches you a lot, but it doesn't provide the same sort of power as a 2500-patient-strong multicountry randomized trial.

So let's talk about SIMPLE. As background, I'll start with two of my more useful biases.

One of my least favorite maneuvers in electrophysiology is delivering shocks to another human. It makes me grimace. Electricity is rough. I've come to like nuance and less-is-more in my electrophysiology. High-voltage shocks are the opposite.

I also don't like inducing cardiac arrest in a live human. Two facts here are relevant: The great majority of patients implanted with ICDs never use the device, and therefore it's more than likely we induce ventricular fibrillation at the time of implant for no reason. My father always advised me not to worry so much about things that might not happen in the future. (Granted, this is not a perfect analogy, but it's close.)

Now to the Study . . .

The SIMPLE trial was exemplary for many reasons:

  • It asked a simple but important question (do DFT testing or not?).

  • It enrolled a large number of patients (n=2500) from 18 countries, and only 1.4% of the cohort was lost to follow-up (no US centers?).

  • Baseline characteristics of both groups were well matched and representative of a typical ICD population.

  • It evaluated clinically relevant "hard" end points.

In brief, the trial's simplicity was its greatest strength. My colleague at Steve Stiles has this detailed recap.

I'll offer a much shorter summary: When 1253 patients enrolled in the defibrillation-testing (DT) arm were compared with the 1247 in the no-testing arm over three years, there were no differences in failed shocks for VT/VF or overall mortality. Complications were low in each group, but there were slightly more shock-related events in the testing arm.

Thoughts and Take-aways

The obvious thing that comes to mind is that the collective bias of most operators in my circle of colleagues—who were no longer doing routine DFT testing—was correct. We had decided that modern-day ICDs nearly always worked, and the tiny, but not zero, risk of inducing VF wasn't worth the gain. It's nice being correct.

But what is especially nice here is what this says about doctors' motivation. In this day, where doctors face criticism for doing procedures for financial gain, the widespread abandonment of a reimbursed "easy" procedure strengthens my belief that the primary motivator for doctors is doing what is best for their patient. Yes, of course, money is always relevant, but doing the right thing comes first for the great majority of physicians.

My friend Dr Jay Schloss (Christ Hospital, Cincinnati, OH) reminded me of our past practice of implanting atrial leads to create dual-chamber ICDs. We did this extra work without pay because we believed that dual-chamber devices were superior. Although in this case the collective wisdom was wrong, the point remains that doing what we believed as the right thing was our motivator.

It's also worth considering what the SIMPLE trial does not tell us. For this, we should look at the baseline characteristics of the included patients and the exclusion criteria. Patients referred for right-sided implants and those at generator change were excluded. The generator change is an important time for thinking, not just about whether ICD benefit remains, but also about technical aspects, such as lead integrity and future performance.

Consider also that women were underrepresented, at only 20% of the cohort. Patients with unusual ICD indications, such as hypertrophic cardiomyopathy and channelopathies, made up less than 5% of the cohort.

In my opinion, the SIMPLE trial speaks to the strategy of routine testing of ICDs in most cases of ICD implantation. Ah. If only much of the practice of medicine were routine. Consider, for example, the case of the young mother with nonischemic cardiomyopathy referred for a secondary-prevention ICD. Here, I hope you agree that the SIMPLE trial does not preclude old-fashioned clinical judgment.

Please. Please don't take our judgment away.



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