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Myocardial fibrosis measures may help decisions about electronic device implantation

Journal of the American College of Cardiology
Reuters Health - 25/02/2022 - Assessing myocardial fibrosis by cardiac magnetic resonance (CMR) may be useful in determining which patients can safely receive a cardiac implanted electronic device (CIED), with or without a defibrillator, an observational study suggests.

Dr. Francisco Leyva of Aston University in Birmingham, UK and colleagues assessed whether myocardial fibrosis on visual assessment (MFVA) and gray zone fibrosis (GZF) mass predict sudden cardiac death (SCD) and ventricular fibrillation/sustained ventricular tachycardia after CIED implantation.

Their study, published in the Journal of the American College of Cardiology, included 700 patients (mean age, 68; 73%, men; 91%, white), including 27 (3.85%) who experienced SCD and 121 (17.3%) who met the arrhythmic endpoint over a median of 6.93 years.

MFVA predicted SCD (HR, 26.3; negative predictive value, 100%), as well as the arrhythmic endpoint (subdistribution HR, 19.9; NPV, 98.6%).

Compared with no MFVA, a GZF mass measured with the 5SD method (GZF5SD) >17 g was associated with the highest risk of SCD (HR., 44.6) and the arrhythmic endpoint (subdistribution HR, 30.3).

Further, adding GZF5SD mass to MFVA led to the reclassification of 39% of patients for SCD and 50.2% for the arrhythmic endpoint.

In contrast, LVEF did not predict either endpoint.

The authors conclude, "In CIED recipients, MFVA excluded patients at risk of SCD and virtually excluded ventricular arrhythmias. Quantified GZF5SD mass added predictive value in relation to SCD and the arrhythmic endpoint."

Drs. Christopher Kramer and Kenneth Bilchick of the University of Virginia Health System in Charlottesville, coauthors of a related editorial, told Reuters Health by email, "Cardiac resynchronization therapy (CRT)... can have a remarkable impact on both quality of life and survival; however, there remains uncertainty regarding who should get a CRT pacemaker or CRT pacemaker-defibrillator."

"By showing that scar seen on CMR predicts dangerous arrhythmias, the present study highlights the potential role of CMR to inform which patients should receive the combination pacemaker-defibrillator device."

"Randomized clinical trials are needed to provide cardiologists with more specific guidance on how to use most effectively the important information from CMR about the structure, function, and location of scar in the hearts of patients with heart failure," they said. "This will help guide decision-making between placing a pacemaker alone or a combination of pacemaker and defibrillator."

Dr. Johanna Contreras, a cardiologist at The Mount Sinai Hospital in New York City, also commented by email. "CMR is a great method to evaluate LVEF, but also to evaluate myocardial tissue, scar tissue, infarct and edema, and we do know that patients with a diagnosis of cardiomyopathy that have late gadolinium enhancement (LGE) on CMR have increased mortality. They are more likely to have arrhythmias and SCD from fatal ventricular arrhythmias."

"However," she said, "it depends on the kind, location and size of the scar and the time in the disease that the CMR was performed. CMR certainly can orient the clinician in cases where there are conflicting data and borderline indications to determine if patients will benefit from ICD, CRT-D, CRT-P, like in certain non-ischemic cardiomyopathy cases."

"But, we still need to have more data from well designed randomized clinical trials with hard end-points," she said. "Plus, CMR is a new imaging technique that requires specialized training and expert interpretation and currently is not available in many centers, which will limit its applicability to the general population."

"I am optimistic that there will be new data coming and that we (will be able to) make better determinations about patient selection," she said.

Dr. Leyva did not respond to requests for a comment.

Financial support in the form of unrestricted educational grants from Medtronic, Boston Scientific, Abbott, and Microport covered salaries of six coauthors.

SOURCE: https://bit.ly/3t6Y5NS and https://bit.ly/3vi9xsq Journal of the American College of Cardiology, online February 14, 2022.

By Marilynn Larkin

© 2023 The Author(s). Published by Medicom Medical Publishers.
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