Delayed enhancement cardiac magnetic resonance imaging (DE-CMR) and programmed ventricular stimulation (PVS) may be used to identify patients with frequent premature ventricular complexes (PVCs) and no apparent structural heart disease who may be at risk for ventricular tachycardia (VT), according to study results published in Heart Rhythm.
Frequent PVCs may indicate structural heart disease; however, echocardiography and stress testing often do not show apparent heart disease in patients with frequent PVCs. The objective of this study was to determine the prevalence of myocardial scarring using DE-CMR and the value of PVS for risk stratification in patients with frequent PVCs.
In this study, researchers evaluated 272 patients with frequent PVCs without apparent structural heart disease who were referred for catheter ablation between December 2004 and December 2017. All patients underwent DE-CMR imaging within 2 weeks before ablation, and those with myocardial scarring had scar volume measured. All patients also underwent PVS and were monitored for ventricular arrhythmia. Researchers used logistic regression analysis to identify the association between clinical characteristics and the presence of scarring and formation of VT and used Cox regression to determine whether scar and VT formation were predictive of survival free from VT.
Results revealed that 25% of patients (n=67) had myocardial scarring. These patients were older, more likely to be men, and had arterial hypertension, chronic obstructive pulmonary disease, and lower preablation ejection fraction. Ablation was successful in 81% of patients (n=220), who had a similar age, were less likely to be men, and had similar preablation PVC burden but higher preprocedure ejection fraction.
Inducible VT was found in 2.6% of patients (n=7), who tended to be older, were more likely to be men, and had higher rates of renal insufficiency.
The presence of DE-CMR was related to the risk for future VT independent of the postablation ejection fraction (hazard ratio [HR], 18.8; 95% CI, 2.0-176.6; P =.01).
The total scar size correlated with the risk for VT at follow-up, independent of postablation ejection fraction (HR, 1.4/cm3 scar; 95% CI, 1.1-1.7/cm3 scar; P <.006). The positive predictive and negative predictive values of VT inducibility for VT at follow-up were 71% and 100%, respectively.
This study had a few limitations. First, the study included only patients who were referred for catheter ablation of PVCs. Second, there were a small number of end point events that precluded multivariable analyses. Third, asymptomatic VT may not have been detected in patients without implantable cardiac defibrillators. Last, workup including fluorodeoxyglucose positron emission tomography for the etiology of intramural scarring was not systematically performed.
The study researchers concluded that DE-CMR and PVS should be considered in all patients with frequent PVCs and no apparent heart disease, especially in the presence of myocardial scarring, and that implantable cardiac defibrillators should be recommended when PVS demonstrates inducible VT due to high VT risk at follow-up.
Ghannam M, Siontis KC, Kim MH, et al. Risk stratification in patients with frequent premature ventricular complexes in the absence of known heart disease [published online September 30, 2019]. Heart Rhythm. doi:10.1016/j.hrthm.2019.09.027