CMR Could Help Identify Concealed Structural Cardiac Abnormalities in Patients With Frequent PVCs

Cardiac magnetic resonance (CMR) imaging was found to detect concealed structural cardiac abnormalities in 16% of patients with idiopathic frequent premature ventricular contractions (PVCs), according to a study published in JACC: Clinical Electrophysiology.

Little is known about the diagnostic utility of CMR imaging in patients with frequent PVCs and an otherwise normal workup, or about the prognostic value of incidental abnormalities detected on CMR.

In this multicenter, international observational study, 518 patients (mean age, 44 years; 56.9% men) who had frequent  idiopathic PVCs (ie, >1000/24 hours; median 24-hour PVC burden, 16% of total beat count), but an otherwise normal routine diagnostic workup, were enrolled between 2002 and 2017. A total of 77% of participants reported palpitations, 13% were asymptomatic, and multifocal PVCs were detected in 7.5% of participants. Participants were imaged with CMR with late gadolinium enhancement (LGE) to detect fibrosis/necrosis and had follow-ups at 3- to 6-month intervals post-CMR.

The study’s primary outcome was a composite of sudden cardiac death, resuscitated cardiac arrest, and sustained ventricular tachycardia or nonfatal ventricular fibrillation that required implantation of a cardioverter-defibrillator.

Myocardial abnormalities were detected in 85 patients (16.4%), with 82 participants (15.8%) showing evidence of LGE. There was an independent association between the presence of abnormalities on CMR and age (odds ratio [OR], 1.04; 95% CI, 1.01-1.06; P <.01), male sex (OR, 4.28; 95% CI, 2.06-8.93; P =.01), family history of cardiomyopathy and/or sudden cardiac death (OR, 3.61; 95% CI, 1.33-9.82; P =.01), and the presence of non-left bundle branch block-inferior axis morphology (OR, 14.11; 95% CI, 7.35-27.07; P <.01) or of multifocal PVCs (OR, 11.12; 95% CI, 4.35-28.46; P <.01) at baseline.

During follow-up (median, 67 months), the composite outcome occurred in 26 patients (5.0%), with a higher incidence of malignant arrhythmic events in participants with vs without CMR abnormalities (29.4% vs 0.2%, respectively; P <.01). During follow-up, 3 participants (0.6%) had SCD, 19 participants (3.7%) had a resuscitated cardiac arrest, and 4 patients (1%) had adequate implantable cardioverter-defibrillator shocks.

Study limitations include a possible selection/referral bias and a possible exclusion of confounders leading to an overestimation of the prevalence of CMR abnormality.

“These findings demonstrate the clinical relevance of CMR imaging for risk stratification of subjects otherwise considered at low risk on the basis of routine diagnostic investigations,” noted the authors. They recommended that future research involve large randomized clinical trials with extended follow-up and a focus on accurately evaluating the prognostic utility of CMR abnormalities.

Funding

Funded in part by the Richard T. and Angela Clark Innovation Fund and the Mark S. Marchlinski Research Fund in Cardiac Electrophysiology.

Reference

Muser D, Santangeli P, Castro SA, et al. Risk stratification of patients with apparently idiopathic premature ventricular contractions: a multicenter international CMR registry. JACC Clin Electrophysiol. December 2019. doi: 10.1016/j.jacep.2019.10.015