Part 2 of my favorite ICD-related posts from HRS 2012

Let's run through quick list of abstracts that piqued my interest.

Importance of sleep apnea in patients with ICDs

I like to tell my ICD patients that having a defibrillator does not negate the need to stay on the program. This means paying attention to primordial-prevention behaviors like exercise, nutrition, and sleep. For if patients continue to overeat, fail to move, and don't sleep well, what's the point of having an ICD?

Two abstracts on sleep apnea were notable. A group from Bonn Germany reported on 133 consecutive patients who underwent sleep studies before the ICD implant. Sleep-disordered breathing (SDB) was found in 62% of the cohort. Compared with patients with normal sleep patterns, those with SDB had a higher incidence of both appropriate and inappropriate shocks. They speculated on the possibility that treatment of obstructive sleep apnea (OSA) may prove to be "arrhythmia reducing."

Similarly, when researchers from Wisconsin and Arizona looked back at a cohort of 285 ICD patients followed over three years, they found those with OSA (17%) documented at the time of implant had more VT, appropriate shocks, and hospitalizations.

Count me as a believer in sleep. I look for sleep abnormalities a lot.

Remote monitoring

The primary reason to implant an ICD is to extend life. That's obvious. Currently, however, an ICD offers more than just a shock. Patients implanted with modern-day devices also enjoy the benefits of remote rhythm monitoring. Take the elderly fragile man I saw recently because of a high-ventricular rate alert. In reviewing the episode we discovered that he had unknowingly gone into AF with a rapid ventricular response. During a same-day office evaluation, we noted subtle signs of heart failure and successful outpatient treatment was started. Remote monitoring had averted a near-certain hospitalization, an inappropriate shock, and perhaps a stroke.

Numerous abstracts compared home monitoring with conventional office follow-up. Modern technology won handily. Home monitoring of ICDs lessened unnecessary in-person encounters, diagnosed AF sooner, reduced shocks, decreased hospitalizations, and saved money. These findings shine a bright light on the upside of technology advances in ICDs and e-connectivity. Amazing stuff, really.

Notes on ICD complications

Inappropriate shocks--Attention to smart programming is critical

One of the major risks of an ICD is that it can deliver an inappropriate shock. I take it personally when this happens to my patients. Why? Because I believe smart programming and adjustment of medicines should prevent most instances of ICD confusion.

Device companies and some groups have purported that an atrial lead helps discriminate SVT from VT. I don't agree. Here's an abstract from the UK that confirms my suspicion. In a look-back study of 570 patients with ICDs, researchers showed that the presence of an atrial lead did not reduce inappropriate shocks. 

Simple programming maneuvers can greatly reduce the risk of shocks. In this study, a group from Tours, France documents the effectiveness of using high-rate cutoffs (up to 220 bpm) to decrease shocks. Likewise, this multicenter European study demonstrated that increasing the number of intervals to detect VT/VF reduced therapies by 37%. In both trials, safety outcomes were not adversely affected by the therapy-delaying strategies. In other words, employing a "not-too-early" approach to ICD programming looks to be safe.

Another hot topic in ICD management is the role of antitachycardia pacing (ATP). At its best, ATP painlessly terminates tachyarrhythmia and the patient avoids a shock. Again, programming ICDs requires skill. Looking back at a series of 308 ICD patients,  researchers from the University of Wisconsin report inappropriate ATP—that which occurred for atrial arrhythmias—increased the risk of inappropriate shocks.

My take-home here is that the modern-day full-featured ICD needs to be individualized to the patient. Implanters must be more than just installers. We must temper our expectations of proprietary "automatic" features of an ICD. Though smarter, ICDs are still pretty dumb. Patients with defibrillators need a doctor, not just an installer.

Do lead revisions only when necessary

Revising ICD leads is risky. This is the conclusion of a multicenter review of 65 774 ICD surgeries culled from seven months of National Cardiovascular Data Registry (NCDR) data. After controlling for important clinical factors, researchers report that patients who underwent lead revisions suffered serious complications (like perforation, hemothorax, and venous obstruction) more than twice as often as those who had ICD implants without revisions. Sobering reports like this one should give ICD doctors pause before messing with leads.

The idea that not all lead alerts warrant surgery was highlighted in this two-patient case report from UCSF. The researchers describe the common scenario where home monitoring found lead-impedance irregularities. Rather than having lead-revision surgery, both these patients did well with intensified monitoring.

These studies remind me of the old saying that instructs one to let a sleeping dog sleep. This philosophy often works well in the management of ICD leads—and lots of other things medical.

One exception may be the Sprint Fidelis lead. Unfortunately, I, like many ICD implanters, have gained too much experience with Fidelis. Gosh, these leads have been a real burr! The question of the moment involves what to do with the troubled lead when an affected patient presents for elective generator replacement due to battery depletion. There are two lines of reasoning here: one group suggests leaving the lead alone if it shows no signs of electrical issues. The other group, which includes me, thinks that the high (and increasing over time) failure rates with Fidelis warrant doing something definitive with the recalled lead at the time of generator change. This might mean switching LV and RV ports in a CRT device—like this paper suggests, abandoning the lead altogether, or extracting it. It just makes common sense to address the lead at a time when the pocket will be open.

Adding to this line of reasoning is the issue of cost. Researchers from Vancouver presented compelling data supporting the conclusion that it is less expensive to deal with the lead electively rather than emergently, which is often the case when Fidelis fails.

Female patients have a higher risk of perforation

Every time I implant an ICD in a woman, I worry about pushing too hard with the lead. "Go easy, John," I say to myself. It turns out this concern is well placed. Reviewing more than 300 000 ICD implants in the NCDR database, researchers from Yale report that female gender greatly increased the risk of cardiac perforation. Other less obvious risk factors for perforation include the presence of sustained monomorphic VT and PCI within the past 90 days (oops). As expected, prior heart surgery protects against perforation.

Think twice about moving a device for radiation therapy

Not infrequently I am asked to move a pacemaker or ICD to the other side of the chest so that a patient can have radiation therapy. As if scarred-in intravascular devices can be easily moved. This study from the prolific group at the University of Michigan tells us that maybe this dogma needs another look. In a series of 70 patients with cardiac devices who underwent radiation therapy, they found ICD or pacemaker malfunction due to indirect radiation was both unusual and easily remedied. No patient suffered a serious outcome. They recommended regular in-treatment or home interrogation of the device during radiation therapy. I like this trial because it addresses a "scary" problem heretofore with scant information available to guide us.  

That's it for ICD abstracts of interest.

I suspect the next big story about ICDs will involve the sub-Q (leadless ICD). There were a number of abstracts on this device. I stopped by the Cameron Health booth and got to handle the bulky and very heavy device. It's going to be an interesting story for a lot of reasons, not the least of which is the concept that offering fewer features is its chief attraction. That's funny isn't it? Less is more keeps coming up in medicine. Surely, I'll have more to say about this soon-to-be approved device.

Also pending review and deserving of a separate post is a look at the many abstracts concerning CRT. For an electrophysiologist there are few more satisfying moments than bearing witness to the patient who enjoys a "super" response from CRT. It's nearly as joyful as a successful AF ablation.

See you all soon.

Thanks for reading.

JMM

Your comments

	Part 2 of my favorite ICD-related posts from HRS 2012
	# 1 of 4	June 4, 2012 12:23 (EDT)
	Don L	Speaking of remote monitoring, I was shocked the first time my cardiologist gave me an event monitor to wear.  To report my results, I had to put the device up against a telephone mouthpiece and push a button, wherupon it emitted an earsplitting series of whistles and wails.  I couldn't believe that it was using acoustic coupling; a technology that went out of date in the 1980s.  "Where's the USB port?", I kept wondering.  (This was only 4 years ago). When I commented about this, the response was that many elderly patients don't have access to a computer, but they all have telephones.
	# 2 of 4	June 4, 2012 01:39 (EDT)
	Ken Grauer, MD	CLINICAL APPLICATION of your point about OSA (Obstructive Sleep Apnea) - IF you see bradyarrhythmias including pauses (as well as runs of VT) during the early morning hours when you inspect telemetry tracings on morning rounds from the night before - THINK OF OSA. As you state - Treatment of OSA may "cure" these arrhythmias (as well as lower blood pressure, relieve headaches, daytime sleepiness and cardio-protect). Would seem that REMOTE monitoring may also detect abnormal brady as well as tachy episodes - for diagnosis of sick sinus (and perhaps, as per above - suggesting OSA as an underlying diagnosis in some patients ... ). Finally - GREAT points you make about Inappropriate shocks!  THANKS for the Updates - : ) Ken
	# 3 of 4	June 4, 2012 01:55 (EDT)
	Ken Grauer, MD	FOR DR. JOHN: The question of how high to program the ICD for shock delivery recently arose in discussion on the EKG Club site about a regular WCT rhythm. The patient had an ICD that did not go off. Realizing that the French study group abstract that you cited (by Clementy et al) did not encounter increased mortality from an initial strategy of a relatively high cut-off rate (220/min) which could then be reprogrammed if needed - it seems risky to me to set the rate so high? Would could be worse than for a patient "reassured" by ICD implantation to develop VT at 170-180/minute and die from it because the ICD didn't go off ... I realize there is no "perfect" solution: Setting lower cut-off rates invites inappropriate shocks - but setting higher ones may miss certain VTs that could prove lethal at a lower VT rate (say 170-180/minute). Please give me insight: WHAT do YOU usually select as your cut-off for ICD shock delivery in a patient you are trying to protect from VT? What clinical parameters do you individualize in selecting that rate-limit? THANK YOU!
	# 4 of 4	June 7, 2012 04:01 (EDT)
	Carey	I'm very glad you take it personally when "your" ICD users experience inappropriate shock. My EP will take it personally too, if or when that happens (I hope. or maybe I'll make it so. for sure, I'll take it personally).   Since I got an ICD for primary prevention, and since these days it seems as if my chances of getting an inappropriate shock are higher than my chances of having my life saved by the device, I'm wondering -- why? was it ever put that way? so -- why'd I agree?? and does it make sense to keep implanting more and more people for whom the same is true?? p.s. I requested that my cut-off rate be set at > 200, and that my interval settings be increased, and my ATP settings be maximized. Most from reading articles about smart programming. Hope those authors got it right.  Thanks for the review.

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