COMMENTARY

CardioStim, Day 1 2014: Does 'Brand' Choice Of Implantable Cardiac Devices Matter?

John Mandrola

Disclosures

June 18, 2014

Maybe you are like me when it comes to choosing an implantable cardiac device—a brand agnostic. Maybe you feel that all the major manufacturers produce remarkably similar devices, and then they leapfrog each other in producing incremental improvements over time. The analogy to high-end bicycles and cars fits: sure, there may be minor differences in features, but ultimately, for outcomes, each device does the job well.

A study presented here at CardioStim 2014 in Nice, France may change your mind, at least for patients implanted with cardiac resynchronization therapy (CRT) devices[1].

Dr Mintu Turakhia (Stanford University, CA) and colleagues presented a provocative study in which they found CRT-D patients implanted with a quadripolar, rather than bipolar, left ventricular lead had an 18% lower chance of dying over a two-year follow-up period. The catch, of course, is that the only available quadripolar lead (in the US) is made by St Jude Medical, which provided financial support for the trial.

Let me tell you about the trial, my conversation with Dr Turakhia, and then my experience with the lead.

The Study

The researchers' aim was to compare all-cause mortality in patients implanted with a CRT-D device with either a quadripolar or bipolar LV lead. The reason to ask this question is that quadripolar LV leads have theoretical and documented advantages over bipolar leads. These include higher rates of implant success and CRT response and lower rates of dislodgment, phrenic-nerve stimulation, and lead revisions. But the question remains as to whether these surrogate measures translate to a lower death rate. (The cardiology community has recently learned important lessons about surrogate measures not being substitutes for real outcomes.)

The way the research team went about answering this question was to analyze remote monitoring data from the St Jude Merlin data warehouse. They then matched Social Security death indexes and compared patients implanted with quadripolar vs bipolar leads.

Patients were included if they had a de novo CRT-D device between 2011 and 2013. The analysis included 17 820 patients who received a quadripolar lead and 5080 who had a bipolar lead. Importantly, the average age, gender, and percentage on remote monitoring were nearly identical in both groups.

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The mortality incidence was 5.84 deaths per 100 patient-years in the group with quadripolar leads and 7.14 deaths per 100 patient-years in the group with bipolar leads (p=0.004). The hazard ratio after multivariate adjustment was 0.819. Other factors that remained significant after adjustment for confounding were an increased risk of death with male gender, increased age, and lack of remote monitoring.

The authors concluded that CRT with a quadripolar LV system was associated with an 18% relative reduction of death and that major confounding factors such as age, sex, and remote monitoring did not explain these differences.

Comments

When I spoke with Dr Turakhia, he reiterated the limits of observational association trials, namely, the problem of confounding. The lower mortality may not be due to the LV lead. It may be something other than age, gender, and percentage of remote monitoring. And he was also careful to point out, first, in fact, that this was a St Jude–sponsored study. (It was refreshing that he led our conversation with the trial's limitations.)

Nonetheless, I consider this remarkable data.

Let's start with the plausibility issue. It is quite plausible that having more choices of LV pacing improves outcomes. Here are the two most obvious reasons:

· LV lead separation and preexcitation of the latest area of LV activation improves CRT response rate and hemodynamics. It follows, then, that a lead with four electrodes could offer more effective resynchronization.

· It is also well established that lead-revision surgery increases the risk of complications. Being able to push a quadripolar LV lead farther into the vein—and then avoid phrenic capture by pacing from a more proximal electrode—decreases the risk of dislodgement. Fewer dislodgments means patients receive less healthcare. And I'm not sure there is a more plausible argument than that.

But perhaps you want something more specific than less healthcare equals better health? Consider this multicenter study presented at the Heart Rhythm Society 2014 Sessions, in which quadripolar leads resulted in remarkably low rates of lead reoperations, phrenic stimulation, and procedural and fluoroscopic times[2].

That's the plausibility argument. This CardioStim poster presentation is also strong on its merits. Consider the large numbers of patients, the choice of the hardest of end points, death, which is easy to count, and the high frequency of reaching the end point (nearly 1000 patients died during follow-up). Also, patients were well matched in age, gender, and the percentage of remote monitoring, which are each strong influencers of mortality. The probability of another significant mortality confounder is low.

My (early) experience with these quadripolar leads has been favorable. As an implanting physician who despises reoperations (more healthcare), I have found the ability to deep-seat these leads and pace from proximal electrodes to be a wonderful feature. In device clinic follow-up, we have used the numerous quadripolar lead choices to "cure" phrenic-nerve stimulation and early battery depletion (high thresholds) by simple reprogramming.

When asked to comment on these leads on a morning run (interview), Dr Jay Schloss (Christ Hospital, Cincinnati, OH) raised the issue of cost. Quadripolar St Jude LV leads are sold to his hospital at a premium price. So yes, initial cost is surely an important issue. Another is future cost. This single-center Italian registry study, also presented today at CardioStim, showed significant (future) cost savings with the quadripolar lead[3]. The mechanism of said savings: fewer hospital admissions.

So . . . are you still brand agnostic?

Does this favorable, plausible, statistically significant two-year mortality data overcome your worry over having four cables running together in a thin St Jude Medical lead?

JMM

Comments

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