Oct 04, 2024 This Week in Cardiology Podcast

Reader feedback on LGE pre-ICDs, PFA for AF ablation, CTO-PCI, endovascular ablation of the greater splanchnic nerve in HFpEF, and data sharing are the topics John Mandrola, MD, covers this week.
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In This Week’s Podcast
For the week ending Oct 4, 2024, John Mandrola, MD, comments on the following news and features stories: Reader feedback on late gadolinium enhancement (LGE) pre-implantable cardioverter-defibrillators (ICDs), pulsed field ablation (PFA) for atrial fibrillation (AF), chronic total coronary occlusion-percutaneous coronary intervention (CTO-PCI), endovascular ablation of the greater splanchnic nerve in patients with heart failure with reserved ejection fraction (HFpEF), and data sharing.
Listener Feedback on LGE before ICD
Sept 27, 2024 This Week in Cardiology Podcast
Last week I reported on a meta-analysis of observational studies of LGE in patients with nonischemic cardiomyopathy (NICM). At issue was the concept of risk stratification. Electrophysiology (EP) doctors care about predicting risk because we are asked to consider ICD placement in these patients.
At this moment, and for the past two decades, we base our ICD decision solely on left ventricular (LV) EF, as LVEF was an entry criterion for the seminal ICD trials. When the seminal ICD trials were done, LVEF was the best risk stratifier we had. Times have changed and now, many patients with newly diagnosed NICM get a cardiac magnetic resonance (CMR) imaging. CMR detects LGE, or scar.
The JAMA meta-analysis of more than 100 smaller observational studies reported a strong correlation between scar and ventricular arrhythmia, sudden death, HF, and overall mortality.
It’s a compelling association because epidemiologic data comports with biologic plausibility. Namely, scar can act as a nidus for reentry.
Regarding the meta-analysis that found strong associations of LGE and risk, I spoke in optimistic tones about the possibility of using LGE on CMR to guide ICD recommendations. Of course, an ICD recommendation is basically a surrogate marker for arrhythmic risk.
The failure of the 2016 DANISH trial of ICD vs no ICD in patients with NICM to confirm an ICD benefit could possibly be explained by the fact that modern-day NICM patients have a lower arrhythmic risk compared with 20 years ago. The lower rates of arrhythmic death may be because medical therapy is better, or it may be because LVEF is not the best risk stratifier. Had we used scar burden as measured by LGE on CMR, we may have enrolled higher risk patients and given an ICD a better chance at lowering mortality. In fact, there are at least two ongoing randomized controlled trials (RCTs) using LGE to guide ICD decision making.
That was a bunch of words to say I was swayed by the meta-analysis and the idea of risk-stratifying with LGE.
However, an expert in imaging and an artificial intelligence (AI) researcher sent me a note of caution. He argued that, a) LGE tracks with LVEF, so, even with adjustments, many of the observational studies included in the meta-analysis could be confounded, and b) LGE is difficult to quantify.
My expert writer noted that the precision (or intraclass correlation coefficient for LGE is not so great. Perhaps even more variation than LVEF. (The reliability of measurement is important; I make fun all the time when patients worry about an LVEF measure. Say, it was 43% and now it’s 41%. I tell them this is much like the data showing judges give harsher sentences before lunch.) The reason why I share this reader feedback is that I did not know there were reliability issues with LGE reporting.
Transcript in its entirety can be found by clicking here:
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