May 6 2022 This Week in Cardiology

COMMENTARY

May 6, 2022 This Week in Cardiology Podcast

John M. Mandrola, MD

Disclosures

May 06, 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 May 6, 2022, John Mandrola, MD comments on the following news and features stories.

General Comments on the Heart Rhythm Society (HRS) Meeting

Electrophysiology (EP) is a small enough sub-specialty that you get to know people over the years. It felt good to see old friends and colleagues in real life, including a fair number of international friends. On a personal note, I was happy with my talks.

  • I debated Vivek Reddy on left atrial appendage occlusion (LAAO). The show of hands at the end revealed the usual: I lost. But the debate was held in the biggest room of the Congress and it was incredibly well attended, which means that many people got to see my slides and the data. It’s the data on percutaneous LAAO that tells the story on why this procedure is a bad idea.

  • My second debate was a lot lower key: I took the antagonist the position that atrial fibrillation (AF) ablation should be first line therapy in athletes with AF. My argument here was not that ablation should not be used in athletes, but that we should try other things first, such as risk factor modification, simply waiting, or detraining, and then ablate if AF persists. I have personal experience here in that I had AF during a run-up to a national championship in bike racing, and the Voltaire approach (waiting) worked—my AF slowly dissipated and I avoided thermal energy in my left atrium.

  • I gave a brief critical appraisal of the EAST AF net trial (early rhythm control vs standard of care) and proposed what future trials should look like. This was a good session and it made me think about whether we can actually design a study of AF treatment strategies, per se. The problem is that AF is such a diverse condition, affecting young healthy people in much different ways than an elderly person with heart failure with preserved ejection fraction (HFpEF).

  • My final talk was on social media, specifically, how to handle disagreements or being wrong on social media. Although I believe in the power of social media, I have too slowly learned some basic lessons:

    • Never argue on Twitter.

    • To persuade, use long-form format, like podcasts and blogs.

    • If you are employed and want to stay employed, avoid politicized issues, such as COVID. Period.

There were no ground-breaking, CABANA-like papers at the HRS meeting. But there was news.

Conduction System Pacing

For my entire career, pacing has been the offensive line of EP; it is necessary but it gets little attention. Catheter ablation has been the quarterback, running back, and receivers. Ablation hogs the attention. But at HRS, pacing made a comeback into the limelight with the rise of conduction system pacing. Three late-breakers addressed the role of placing a pacing lead in the rapidly conducting His-Purkinje system or specialized conduction system.

I have been an early adopter of His bundle pacing (HBP), but now the field has moved on to left bundle branch (LBB) pacing. LBB pacing is easier and produces far better pacing and sensing thresholds. The lead captures the left bundle, or it excites the left bundle early, and this leads to synchronous left ventricle (LV) and right ventricle (RV) contraction, and gorgeous paced QRS complexes.

But until HRS, we had little data. Here are the highlights from HRS.

LBCT LBBP study 1: LBBP-RESYNC was a randomized controlled trial that compared the efficacy of LBB pacing with conventional biventricular pacing in 40 patients with heart failure who were eligible for cardiac resynchronization therapy (CRT). The primary endpoint was the change in LV ejection fraction (EF) from baseline to 6-month follow-up.

  • Both pacing techniques improved LVEF from baseline.

  • The between group difference in the LVEF was greater in the LBB pacing arm than the biventricular pacing arm by a statistically significant 5.6% (95% confidence interval [CI]; 0.3%-10.9%).

  • Secondary endpoints, such as reductions in left ventricular end-systolic volume, NT-proBNP, and QRS duration also favored LBB pacing.

Conduction System Pacing vs Biventricular Pacing. A second late-breaking study, from the Geisinger group, led by Pugazhendhi Vijayaraman, MD, was simultaneously published in Heart Rhythm journal. This was a non-randomized observational study comparing nearly 500 patients eligible for CRT who were treated at two health systems. One group favors conduction system pacing (CSP) and the other does traditional biventricular pacing, which set up a two-armed comparison.

  • CSP was accomplished by LBB pacing (65%) and His-bundle pacing (35%).

  • The primary endpoint of either death or first hospitalization for heart failure occurred in 28.3% of patients in the CSP arm vs 38.4% of the biventricular arm (hazard ratio [HR] = 1.52; 95% CI, 1.08-2.09).

  • QRS duration and LVEF also improved from baseline in both groups.

LBB Area Pacing as a Bailout for Failed CRT. The Geisinger group also presented a multicenter study that assessed the feasibility of LBB pacing as a bailout when standard biventricular pacing did not work, either because of inadequate coronary sinus anatomy or CRT non-response.

  • This series included 212 patients for who CRT failed and who underwent attempted left bundle area pacing.

  • The bailout was successful in 200 patients (91%).

  • The primary endpoint was defined as an increase in LVEF of >5% on echocardiogram.

  • About two-thirds of patients had an improvement in LVEF above 5% and nearly 30% had a “super-response.”

  • Similar to the previous studies, left bundle pacing resulted in shorter QRS duration and improved echocardiography parameters.

Comments: I know these small randomized controlled trials (RCTs) and nonrandomized comparisons aren’t what we are used to in big drug or device trials. But it’s a start. Here is the take-home:

  • Taken together, we learn that LBB pacing appears to increase LVEF similar to CRT and it can be used as a bailout when coronary sinus leads fail.

  • This gives me the sense that when RV pacing is expected, LBB pacing is likely to prevent pacing-induced cardiomyopathy.

I am not yet persuaded on clinical outcomes. The first Geisenger study was non-randomized, and you can’t infer that LBB pacing caused the better outcomes because there are likely other reasons (confounders) that led to the LBB group having better outcomes. But these preliminary data give me confidence that we are on the right track, and that there is surely enough equipoise to compare this technique to biventricular pacing. And I think non-inferiority is a fair way to study it, because LBB pacing is less invasive and less costly. And if I have a pacer, I want a LBB lead.

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