Cardiac Rhythm Management
Articles Articles 2014 June

Letter from the Editor in Chief

DOI: 10.19102/icrm.2014.050601

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Dear Readers,

It is with much sadness that I write this letter. After much consideration I need to step down in my role of Editor-in-Chief of this Journal to focus my efforts on leading the Heart Rhythm Society for the next two years.

Since the Journal launched in September, 2010 we have seen the Journal progressively grow month by month, year by year. Thank you so much for your loyal readership and comments over the last four years.

I am honored to introduce our new Editor-in-Chief, Dr. Moussa Mansour, who is a world-renowned Electrophysiologist, who unquestionably will bring a tremendous amount of expertise, experience, and enthusiasm to the position. Dr. Mansour is the Director of the Cardiac Electrophysiology Laboratory and Director of the Atrial Fibrillation Program at Massachusetts General Hospital, and is an active clinical consultant in all aspects of heart rhythm disorders, including atrial fibrillation, ventricular tachycardia, supraventricular tachycardia, bradycardia and other cardiac arrhythmias. Dr. Mansour performs a large number of catheter ablation procedures and implants pacemakers and defibrillators. He has published extensively in the field of cardiac arrhythmia, specifically the area of Atrial Fibrillation, and is involved in cutting edge research.

Please welcome Dr. Mansour to the Editor-in-Chief position.

For my letter this month I want to focus on the wonderful 35th Annual Scientific Sessions of the Heart Rhythm Society that recently concluded. For 15 months we met weekly and made detailed plans for this meeting. We were so excited to see that scientific attendance was up 15% this year! Many of you felt that same excitement that I did in San Francisco this year.

Back by popular demand, let me share with you the top 10 stories that came out of the HRS Annual Scientific Sessions this year.

10. Dementia and Atrial Fibrillation

We are increasingly learning that atrial fibrillation, and how we treat it, can have long-term consequences on cognitive function. Our group, under the direction of Dr. Jared Bunch, presented several studies looking at risk factors for dementia in atrial fibrillation patients.

Interestingly, we showed that having either a sub-therapeutic or supra-therapeutic INR was a powerful risk factor for long-term dementia in atrial fibrillation patients. We suspect that this may be due to recurrent micro strokes in the patients who are subtherapeutic and recurrent cerebral microbleeds in the patients who are supratherapeutic. We have additional data that supports these hypothesis. Our only hope is that we will observe lower long-term dementia risks with the novel anticoagulants as patients will be in a better therapeutic range with a potentially lower risk of cerebral microbleeds.

In addition, we showed that lower heart rates in patients with persistent atrial fibrillation are also associated with an increased long-term dementia risk. Could it be possible that the decreased cerebral blood flow in atrial fibrillation is only further exacerbated by lower average heart rates in patients with atrial fibrillation? Regardless, these are provacative data and support the notion that we may actually be causing our patient harm by aggressively controlling their heart rates with atrial fibrillation.

9. The Impact of Bariatric Surgery on Incidence of Atrial Fibrillation by Dr. Yong-Mei Cha and colleagues

This Mayo Clinic study builds on previous work in this area. Weight loss, however it is achieved, can have a powerful beneficial effect on atrial fibrillation. While this was just a retrospective study of 438 patients, the results were very striking. Dramatic weight loss resulted in a 3-fold reduction of atrial fibrillation over a 7 year follow-up period.

While weight loss surgery is certainly not the answer for most atrial fibrillation patients, we can encourage our overweight/obese atrial fibrillation patients to lose weight and adopt healthy lifestyles. We have to do something more than just prescribe medications and perform ablations with the atrial fibrillation epidemic we are currently witnessing.

8. Increased Adherence to Remote Monitoring is Associated with Reduced Mortality in Both Pacemaker and Defibrillator Patients by Dr. Suneet Mittal and colleagues.

While this type of study has been done before using other big databases by the other device companies, it is worth mentioning here. In this study of 262,564 patients with St. Jude Medical pacemakers and ICDs, including CRT devices, they showed that patients who faithfully used remote monitoring technology had a 2.4x survival advantage compared to those patients who do not use this technology.

Even those who just occasionally used the technology had a 1.5x survival advantage compared to those who did not use remote monitoring. They also went on to show that education level and other socioeconomic factors failed to predict which patients use remote monitoring technology.

All of the studies done to date looking at this same question have showed the exact same results. Patients with remote monitoring devices live longer.

Why is this the case?

While we would all love to believe that it is the remote monitoring technology that allows patients to live longer, the real answer may not be so simple. It may just be that those who use this technology are motivated and complaint patients and that this survival advantage has absolutely nothing to do with remote monitoring technology. Or it is possible that just having this remote monitoring technology in your home has a placebo effect?

Until the study is done, we will never know the answer. Regardless as to why remote monitoring patients live longer, if we can just encourage our patients to use this technology we can offer them a tremendous survival advantage. As it is so simple to use this technology, I cannot think of a reason why we wouldn't strongly encourage our patients to sign up for remote monitoring.

7. Dual-Targeted Thoracic Spinal Cord Stimulation for HEArt Failure as a Restorative Treatment: First-In-Man Experience by Hung-Fat Tse and colleagues.

This was an interesting multicenter trial from the Asian Pacific area on dual-targeted spinal cord stimulation to treat heart failure. Most of the big pacemaker companies have all invested in "pacemakers" for the spinal cord to improve heart failure.

With this technology, the "pacemaker" generator sits in the lower back and 2 leads run up the back to "pace" the T1-T3 level spinal cord level. This continuous "pacing" of the spinal cord changes the autonomic innervation of the heart to favor vagal stimulation thereby decreasing sympathetic output.

In this study, they showed their results of the first 15 heart failure patients treated with dual-targeted spinal cord stimulation. Remarkably, all heart failure parameters markedly improved with this therapy, including a dramatic increase in the left ventricular ejection fraction.

Before we get too excited about this innovative new treatment strategy for heart failure, we are all aware of how all of the enthusiasm for renal denervation suddenly died. It took a sham procedure in the control group to show that there was no benefit from renal denervation. Also, as we have seen from countless pacemaker studies over the years, there is a powerful placebo effect that happens when you implant something in a patient.

Stay tuned on this exciting new technology as more studies are underway.

6. Adenosine-guided pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation: Results of the prospective multicenter randomized ADVICE trial

Pulmonary vein reconnection has been the achilles heal of atrial fibrillation ablation procedures. To help overcome this there have been a number of possible strategies that have been proposed. Recently, many small studies have suggested that adenosine could be such a tool. We have known for years that adenosine can bring out dormant, partially ablated tissue, at the end of an ablation procedure.

In this multicenter study of 550 patients they had three groups of patients. Following pulmonary vein isolation, they gave adenosine and checked for residual pulmonary vein conduction in each vein. If there was no dormant conduction into the veins with adenosine they finished the case. This happened in roughly half of the patients and I will refer to these patients as group 1.

They then took the other half of the patients with residual pulmonary vein conduction with adenosine and randomized them to two groups. In one group they continued to ablate until they had achieved no dormant conduction with adenosine. I will call this group number two. In the other half of the patients with dormant pulmonary vein conduction they did nothing more. I'll call this group number 3.

If the real goal is to eliminate any potential dormant conduction with adenosine, then you would expect group 1 and 2 to have similar efficacy rates. Interestingly, this was not the case.

The group that required much more ablating to achieve complete elimination of any adenosine induced dormant conduction (group 2, single procedure 1-year success rate of 69.4%), did much better than the group that had no dormant conduction when they first checked (group 1, single procedure 1-year success rate of 55.7%). Not surprisingly, the group that they left with dormant pulmonary vein conduction did the worst (single procedure 1-year success rate of 43%).

If adenosine is really the secret sauce to improving success rates with Afib ablations, then you would expect groups 1 and 2 to be the same. As that was clearly not the case, the answer may be that to get more durable pulmonary vein isolation you just have to ablate much more as many other studies have shown.

5. The Nanostim Leadless Pacemaker Update presented by Dr. Vivek Reddy

As with last year, the Nanostim leadless pacemaker was part of the late breaking clinical trial session. This year, Dr. Vivek Reddy presented the 1 year follow-up data on this new disruptive technology. At one year of follow-up, the reliability of this device remains very strong.

While these one year data are encouraging, a European trial of this technology was recently halted due to a very high rate of cardiac perforations with this new technology. As we learned from the Watchman experience, there is definitely a learning curve with these new first generation devices.

As with the Watchman experience, through proper training and experience as well as improved designs of the technology this obstacle will soon be overcome. We are all longing for the day when we can finally say goodbye to pacemaker and ICD leads.

4. Prophylactic Pulmonary Vein Isolation During Isthmus Ablation for Atrial Flutter: The PReVENT AF Study I by Dr. Jonathan Steinberg and colleagues.

I was very impressed with this bold and innovative study design. While most of us have come to the conclusion that it is just a matter of time before you will be dealing with Afib following an atrial flutter ablation procedure, Dr. Steinberg and colleagues took things one step further by randomizing patients to a prophylactic Afib ablation at the time of their flutter ablation.

To validate their conclusions, they implanted a loop recorder in these patients to ensure that there were no missed episodes of arrhythmia recurrence. While they only randomized 50 patients in this study, that was all that they needed to show a benefit of performing pulmonary vein isolation in atrial flutter patients before they ever experience their first episode of Afib.

While no one would go so far as to recommend that pulmonary vein isolation should be done at the time of a flutter ablation, it is certainly something that should be studied in a larger patient group. Perhaps the isolated simple flutter ablation procedure is something that will go away in the future. It just may be that atrial fibrillation and atrial flutter are really just the same disease manifesting in different chambers of the heart.

3. Ablation of Clinical Stable Ventricular Tachycardia Versus Substrate Base Ablation on long term freedom from any VT: Results from a randomized multicenter study by Dr. Luigi Di Biase and colleagues.

As we well know, one of the most challenging aspects of VT ablation is being able to tediously map an inherently unstable rhythm. For years, we have tried supporting the patient with percutaneous left ventricular assist devices and other technologies while we laboriously tried to map the VT circuits. While this is certainly possible in some patients, for many their VT is just too unstable to map. Also, the problem has been that once the VT has been successfully ablated it is just a matter of time before it returns somewhere else.

Enter into the picture the "scar homogenization" technique of VT ablation. With this approach, the myocardial scar is mapped and then extensive ablation is performed until the scar is really a scar. In other words, any surviving little islands of myocardial tissue within the scar zone are all ablated until the scar becomes completely homogenized.

In this study, these two techniques were compared in a randomized multicenter study involving 118 patients. Interestingly, the substrate based ablation approach or scar homogenization was shown to be much more effective and even reduced the combined end-point of hospitalization and mortality compared to the traditional "map the VT circuit" approach to VT ablation.

This study could truly change our approach to VT ablation as it is much easier to map a scar than to map unstable VT.

2. Aggressive Risk Factor Reduction Study for Atrial Fibrillation (ARREST-AF): Implications for Ablation Outcomes by Dr. Prash Sanders and colleagues

There is a growing movement in EP that we need to address lifestyle modification in order to effectively treat atrial fibrillation. Dr. Sanders and his team should be commended for their recent JAMA article which showed that atrial fibrillation is reversible with significant weight loss. Weight loss, whether through lifestyle changes or weight loss surgery can have a powerful effect on atrial fibrillation.

The most striking thing about the ARREST-AF Study is that in overweight and obese patients, if we don't address the underlying causes of atrial fibrillation, our ablation procedures are often ineffective Indeed, in this study Prash and colleagues showed that the single procedure success rate at 42 months was 62% in those patients making lifestyle changes versus just 26% in those patients that did not make lifestyle changes. When they allowed for multiple procedures, the 42 month success rate rose to 87% in those who made lifestyle changes versus just 48% in those who did not make lifestyle changes.

I cannot begin to share with you just how powerful the results of lifestyle modifications are for the treatment of atrial fibrillation. In our practice, we have now adopted an aggressive lifestyle modification approach and have seen dramatic weight loss and reduction of atrial fibrillation. Even though we just started this program four months ago, we have already seen greater than 40% reduction in atrial fibrillation symptoms, discontinuation of medications in most patients, and dramatic weight loss with lifestyle modification.

Patients really are willing to make lifestyle changes!

1. A Randomized Trial of Defibrillation Testing at the time of ICD implantation: Results of the Shockless Implant Evaluation trial (SIMPLE) by Dr. Jeff Healey and colleagues.

In my opinion this was the biggest study coming out of the Annual Scientific Sessions this year. Since the ICD was FDA approved in 1985, defibrillation testing has been a time honored ritual at the end of ICD implantation. Could it now be that this should no longer be done?

Indeed, these were the findings of the SIMPLE Study. In a multicenter randomized study of 2,500 patients they showed that defibrillation testing at the time of ICD implantation offered no benefit. If anything, there was a strong trend toward increased complications, including the need for CPR and intubation.

It seems counter intuitive but the VF encountered during induction at ICD implantation is just not the same as VF that occurs spontaneously during real life of these patients. With 2,500 patients in this study, there were enough events, in my opinion, to answer this question. Defibrillation testing is just no longer needed with routine ICD implantation.

What was your impression of the meeting this year? Please send me an email and share your thoughts with me.

In closing, I truly hope that the contents of this Journal have been beneficial to you and your patients these past four years. It has been an honor to serve in this capacity as editor and I look forward to even greater success of this Journal in the upcoming years.

Warm regards,


John D. Day, MD, FHRS, FACC
The Journal of Innovations in Cardiac Rhythm Management
Director of Heart Rhythm Services
Intermountain Medical Center
Salt Lake City, UT