Use of cardiac MRI and wearable defibrillator to identify patients at low risk for arrhythmic events: single center experience
Authors: Solarino G , Del Meglio J , Nesti L , Canale M L , Tognarelli A , Cardelli L , Michelotti E , Christou A , De Caro F , Poddighe R , Ferrali E , Marracci L , Casolo G 
Published: May 2024

Abstract

Introduction
In our Center, patients (pts) with newly diagnosed HF and reduced LVEF underwent MRI to determine the presence and extension of delayed enhancement (DE) or scar areas. These patients were discharged with a wearable cardioverter defibrillator (WCD) as monitoring and temporary antiarrhythmic therapy until a three-month follow-up (FU). Subsequent FU was performed at 6 and 12 months.

Methods
From May 2016 to July 2023, 120 consecutive pts (97 M; mean age 65.3y±9.7y) with reduced EF (28.5%±8.5%) on OMT, were discharged with WCD and included in clinical FU. Coronary anatomy was acquired in 119 pts: absence of coronary atherosclerosis (ats) (44 pts); not significant ats(39 pts); Significant ats(36 pts). 1 pt did not perform angiography due to thyrotoxicosis. MRI was performed in 95 pts (EDV 181.9 ± 48.7 ml/m2; Mass 96.9± 23.4 g/m2, LVEF MRI 26.8% ±9.2). FU was performed at 3 months in all patients; at 6 months in 111pts and at 12 months in 107pts. WCD is still present in 4 pts. LGE score was used to quantify myocardial fibrosis by defining reduced extension as LGE score &lt;5.

Results
MRI identified 57 pts with a delayed enhancement(DE) midwall pattern and in 13 of these there was a regional ischemic pattern also; 27 pts with regional scar; 18 pts without DE. During follow-up, 87 patients (75%) recovered LVEF function at 3 months (LVEF 44.3±6.3%) and were no longer indicated for ICD. 29 pts were implanted with ICD (25%). These patients had higher absolute and indexed volumes on MRI (p 0.053; p 0.042) and a greater presence of ischemic pattern (p 0.05). The LGE score was low in 76 pts (&lt;5). A low LGE score is linked to the recovery of LVEF (p 0.04). Patients who undergo ICD had greater DE extension (p 0.01). 1 pt with a high LGE score (36.6) refused ICD and underwent SCD at 6 months.
In pts with LGE score &lt;5, 1 major arrhythmic event occurred (1 SVT in pt with ICD). In pts with LGE score &gt;5, 3 major events occurred (1 shock on VF, 1 ATP on SVT, 1 SCD). 1 pt with extensive anterior akinesia who refused MRI presented 1 shock on VF at 6 months. 1 pt with partial recovery of LVEF and extensive anterior akinesia refused MRI and presented cardiac arrest for VF at 6 months.

Conclusions
MRI has become essential for risk stratification in patients with reduced LVEF. It is useful for identifying pts with severe impairment LVEF and low risk of events. The absence of DE and/or the presence of a low LGE score are linked to a low risk of arrhythmic events at 6 and 12 months and to a higher probability of recovery LVEF regardless of the etiology. The volumetric dimensions found on MRI are inversely linked to the recovery of LVEF. The WCD represents additional safety with excellent compliance in pts who still do not have clear indications for a definitive ICD.
The combined MRI and WCD strategy can help to reduce the need for definitive ICD and therefore healthcare costs. The size of the sample does not allow definitive conclusions.