Apr 22 2022 This Week in Cardiology

COMMENTARY

Apr 22, 2022 This Week in Cardiology Podcast

John M. Mandrola, MD

Disclosures

April 22, 2022

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Please note that the text below is not a full transcript and has not been copyedited. For more insight and commentary on these stories, subscribe to the This Week in Cardiology podcast on Apple Podcasts, Spotify, or your preferred podcast provider. This podcast is intended for healthcare professionals only.

In This Week’s Podcast

For the week ending April 22, 2022, John Mandrola, MD comments on the following news and features stories.

VT Ablation

I want to revisit the comments I made last week on ventricular tachycardia (VT). If you haven’t listened, you might do that first.

I misspoke slightly in my review of the PARTITA study of early VT ablation vs standard care after an implantable cardioverter defibrillator (ICD) shock. The trial found that VT ablation reduced the primary endpoint of death or hospitalizations for heart failure (HHF). I criticized it on many fronts. One was that VT ablation improved overall mortality but did not really reduce VT.

I said this: “Cardiac death, recurrent VT, VT with anti-tachycardia pacing (ATP), or VT with shocks did not differ.”

The last phrase – VT with shocks — was actually lower in the ablation arm; two vs 10 patients, with a P of 0.039. Thanks to Dr. Dimitris Tsiachris for listening so carefully.

Sorry for the mistake. My criticisms still stand: recurrent VT of any type, of which there were more events, did not differ. Again, the primary endpoint of this trial, which had 23 patients in the ablation arm and 24 getting standard care, had a positive endpoint driven by non-cardiac deaths, which could not have been affected by either arm.

I also received an extremely kind email from one of the SURVIVE VT investigators. He disagreed with many of my criticism of SURVIVE VT, a trial conducted in Spain, that compared early VT ablation with substrate ablation and antiarrhythmic drugs (AAD) in patients with ischemic cardiomyopathy (CM) who had an ICD shock.

This trial included 144 patients and a primary endpoint of cardiovascular (CV) death, ICD shock for VT, HHF, or severe treatment-related complications. I want to review some of his most important responses to my criticisms.

  • First, he took issue with my citation of a 14% complication rate. In the supplement they broke down complications into major and minor and here there were eight major complications in seven patients, which is 10%. Two of these were slow VTs that, if excluded, would result in an 8% complication rate. He also points out that AAD also have complications.

My response: Okay, but 8% to 10% is still a high complication rate, especially considering the trial is conducted in super-expert centers on carefully selected patients.

  • Second point of contention: he took issue with my comment that VT ablation should reduce the primary endpoint via reduction of VT. Again, in SURVIVE, rates of ICD shocks, CV deaths, total deaths, and any VT were all similar.

    He said, “You made it sound like VT ablation is a curative procedure and I don’t think that is the case. VT ablation is an adjuvant therapy to ICD aimed at reducing VT recurrent events; the more you reduce them, the better, but I think it is unrealistic to believe that VTs can be eliminated.”

That’s fair, but keep in mind, these were patients who had undergone one ICD therapy or one episode of sustained VT.

  • He also took issue with my critique of calling sinus bradycardia and hypothyroidism severe complications, which made the AAD arm look worse. His rebuttal was that the hypothyroidism was symptomatic and led to discontinuation of amiodarone. And both cases of sinus bradycardia and dyspnea were symptomatic.

That is also fair, but still, none of these are akin to stroke or pericardial tamponade.

  • A fourth disagreement centered on my comments that slow VTs in the AAD arm are not severe complications because part of the efficacy of AAD is to slow VT and if recurrent it can be ablated.

    My gracious colleague from Spain wrote: “AADs slow conduction velocity, but the reason we use them is not to slow VTs, it is to prevent them, right? Suffering a slow VT (undetected and untreated by the ICD) led these patients to the hospital because they were symptomatic, many of them with VT lasting hours and requiring cardioversion. Additionally, five out of these 15 patients (33%) had incessant VT defined as a VT that recurs promptly despite repeated interventions for termination over several hours, and this is a serious condition that may require urgent VT ablation.”

There were some other more minor points of disagreements.

I want to say how much I love these comments and interactions. I learn from them and I hope you can too. I also want to re-iterate strongly that my critical appraisal of a trial is never meant to be personal. I’ve gotten involved in trials and now understand firsthand how damn hard they are to do. This week, I heard results of an NIH trial I was part of, and as proponents of the thing we were studying, we had hoped for stronger results. So, I get it.

My aim here is never to diminish the work of generating evidence. My aim is to help clinicians appraise the evidence in a neutral way and to be able to better translate it to the bedside. And it is true that I have biases. I have lived through many periods of irrational exuberance in cardiology — especially electrophysiology (EP). In large part this happened because we were too easily bamboozled. We were unable to critically appraise the evidence for ourselves. These experiences have led me to becoming medically conservative. So, part of my aim is to provide a cautious approach to new therapies.

American College of Cardiology (ACC): More to Come

I’ve spent two weeks reviewing the ACC meeting. I did not get to all the studies. There are still some more noteworthy topics to sort out from ACC.

One is renal denervation, the SPYRAL-HTN – On Med follow-up study, for instance. I am in a journal club on this next week and will let you know more on this study coming soon. Renal denervation is making a comeback, there are many studies in this space, using different study designs and different devices vs the SYMPLICITY III days. It’s super complicated.

European Heart Rhythm Association (EHRA) Meeting

As ACC was on, the EHRA meeting happened in Copenhagen. It’s quite unfortunate that the two meetings overlapped. I hope that changes in the future.

At EHRA, a number of studies addressed three white-hot topics in EP. I realize EP is a sub-specialty so I will attempt to keep it interesting for a broad audience.

Pulsed-Field Ablation (PFA)

First is a new ablation energy called PFA.

PFA works via electroporation, a technique that involves applying electrical current to the heart, which then disrupts current flow across the cardiac cell membrane. This results in pore formation and cell death.

Recall that the very first ablation was DC shock to the atrioventricular (AV) node. PFA is a super-controlled form of DC shocks. Patients have to be under anesthesia to have it. The main upside of PFA is its cardio-selectivity; it purportedly does not harm the adjacent phrenic nerve or esophagus. It’s also fast. There is much excitement in the EP community about this technique.

Vivek Reddy presented results of a large European experience with the first generation PFA system. It earned the Conformitè Europëenne (CE) Mark about 11 months ago, and Reddy had a survey from 24 European centers and 1700 patients. The study was called MANIFEST PF. The results were mixed.

  • Patients in this retrospective observational survey were typical of an ablation cohort; about 62 years old with a mean CHADSVASC of 2 and normal ejection fractions (EF).

  • All patients had one transseptal puncture, the mean procedure time was 65 minutes (range, 38 to 215 minutes), mean fluoroscopy time was 12.7 minutes (range, 4.5 to 33 minutes), and 16% of patients were discharged the same day.

  • I want to stop there and say that this is not much different than my radiofrequency (RF) ablation procedures and probably longer than my colleagues’ cryoballoon procedures.

  • The success rate using PFA was similar to standard; 99.9% of PVs were isolated.

  • In this survey, there were no esophageal fistulas or pulmonary vein (PV) stenoses. However, there was one (transient) phrenic nerve (PN) injury and coronary vasospasm. The PN injury was very short lived but again, PFA is supposed to be cardio-specific.

  • There was a 1% rate of pericardial tamponade; 17 of 1700. Four required surgery.

  • There were seven strokes, one fatal; incidence 0.4%.

  • There were 56 vascular complications, the majority were hematomas, for a rate of 3%

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