Incremental value of implantable loop recorders in arrhythmia detection and management in cardiomyopathies:...

Implantable loop recorders (ILRs) are increasingly being used for the detection of infrequent arrhythmias in patients with cardiomyopathies, especially in the presence of risk markers. The role of these devices in improving the detection of significant arrhythmias requiring a change in clinical management remains to be determined. Our purpose was to evaluate the diagnostic yield, types of arrhythmia, and subsequent management in cardiomyopathy patients receiving an ILR.

Prospective single-centre study in cardiomyopathy patients considered at borderline risk for ventricular arrhythmias, who received an ILR. The primary endpoint was a meaningful arrhythmic event detection leading to a change in clinical management.

A total of 45 patients were included, 51% were male, median age was 62 (48-71) years. The underlying disease was hypertrophic cardiomyopathy (HCM) in 31 patients (69%), dilated and non-dilated left ventricle cardiomyopathy (DCM/NDLVC) in 12 patients (26%) and transthyretin amyloid cardiomyopathy (ATTR-CM) in 2 patients (4%). The most frequent risk markers were brief run of nonsustained ventricular tachycardia in 42%, unexplained syncope/pre-syncope in 36%, family history of premature sudden cardiac death (SCD) in a first-degree relative in 36%, and palpitations suspicious of arrhythmic origin in 18% of patients. In the HCM cohort, median HCM Risk-SCD score was 3.07 (2.68-3.76)%, with 19% of patients having an estimated 5-year risk of SCD ≥4%. Mean maximum wall thickness was 20±4 mm, mean left atrial diameter was 43±7 mm, 23% of patients had obstructive HCM, late gadolinium enhancement (LGE) was present in 74% - with 52% of patients presenting extensive LGE - and left ventricle apical aneurysm in 3%. A sarcomeric pathogenic variant was identified in 26%. Among the DCM/NDLVC patients, 58% had left ventricular ejection <50%, 25% carried pathogenic/likely pathogenic variants on genetic testing and 25% exhibited an extensive ring-like scar pattern on cardiac magnetic resonance (CMR). During a mean follow-up of 19±13 months, 44% of patients had, at least, one ILR-guided diagnosis. De novo atrial fibrillation was diagnosed in 24% of patients and was the main detected event. Due to ILR-guided diagnosis, 20% (9 patients) received an implantable cardioverter-defibrillator (ICD), one of which with subsequent appropriate ICD-therapies.

This study provides insight into the possible role of ILR in this population, not only for the diagnosis of ventricular arrhythmias, but also for detection of atrial fibrillation, which can lead to a different clinical management.