Clinical significance of myocardial scar in patients with frequent premature ventricular complexes undergoing catheter ablation

Ventricular arrhythmias in patients with bicuspid aortic valves

INTRODUCTION

Bicuspid aortic valves (BAV) are the most common congenital heart defects and the extent of ventricular arrhythmias (VA) in patients with BAV is unclear. The objective of this study is to describe VAs and late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR) in patients with BAV.

METHODS

A total of 19 patients with BAV (18 males, age: 58 ± 13 years) were referred for VA ablation procedures. Ten patients had BAVs at the time of ablation, nine patients had prior aortic valve replacement for a BAV. All but one patient had LGE-CMR and all patients underwent programmed ventricular stimulation at the time of the ablation.

RESULTS

Frequent PVCs were the targeted VAs in 17/19 patients and VT in 2/19 patients. Monomorphic ventricular tachycardia (VT) was inducible in 6 patients. A total of 15 VTs were inducible (2.5 ± 1.0 VTs per patient with a mean cycle length of 322 ± 83 msec). LGE was present in 13 patients. Patients with inducible VT had larger borderzone and core scar compared to non-inducible patients (7.8 ± 2.1 cm3 vs. 2.5 ± 3.1 cm3 and 5.1 ± 2.6 cm3 vs. 1.9 ± 3.0 cm3, p-value < .05 for both). PVCs and VTs were mapped to the periaortic valve area in 12 patients and 4 patients, respectively. The PVC burden was reduced from 27 ± 13 to 3 ± 6 (p < .001) and the ejection fraction improved from 49 ± 13% to 55 ± 9% (p = .005).

CONCLUSIONS

VAs in patients with BAV often originate from the perivalvular area and patients often have LGE and inducible VT. LGE may be due to ventricular remodeling secondary to the presence of BAV and harbors the arrhythmogenic substrate for VT.

Premature Ventricular Contraction-Induced Cardiomyopathy: Contemporary Evidence from Risk Stratification, Pathophysiology, and Management

Premature ventricular complexes (PVCs) are commonly encountered problems in clinical settings. The range of symptoms can be from asymptomatic to palpitations, fatigue, or heart failure symptoms. A higher burden of PVCs is a risk factor for development of PVC-induced cardiomyopathy (PIC). Rhythm evaluation by 12-lead ECG and an ambulatory monitoring device are essential. Currently, several imaging modalities, such as echocardiography and cardiac magnetic resonance imaging, are utilized to evaluate the underlying structure that may be related to PIC. Beta blockers and antiarrhythmic drugs are typically part of the initial management strategy. If these fail, catheter ablation of PVCs is typically the next step. The purpose of this article is to summarize the current evidence/knowledge about PIC.

Strain Analysis in Patients with Frequent Premature Ventricular Complexes and Preserved Left Ventricular Function Undergoing Ablation

BACKGROUND

Frequent premature ventricular complexes (PVCs) can cause PVC-induced cardiomyopathy. The value of PVC ablation in patients with preserved left ventricular function in the low-normal range (ejection fraction: 50-55%) is not established. Strain analysis has been used to estimate changes in left ventricular function beyond assessment of the ejection fraction (EF). Longitudinal strain has been proposed as a method to detect changes over time in the setting of frequent asymptomatic premature ventricular complexes and preserved left ventricular (LV) function. A decrease in strain may be evidence of PVC-induced cardiomyopathy.

OBJECTIVE

In this study, we assessed the role of PVC ablation in patients with low-normal EF and the effect on EF and myocardial strain before and after PVC ablation.

METHODS

A total of 70 consecutive patients with either low-normal EF (0.5-<0.55, n = 35) or high-normal EF (≥0.55; n = 35), using available imaging and Holter data, were referred for ablation due to frequent PVCs. EF and longitudinal strain were assessed pre- and post-ablation.

RESULTS

There was a significant increase in EF (53.2 ± 0.4% to 58.3 ± 0.5%, p < 0.001) and improvement in longitudinal strain (-15.2 ± 3.3 to -16.6 ± 3, p = 0.007) post-ablation in patients with low-normal EF and successful ablation. There was no change in EF or longitudinal strain in patients with high-normal EF and a successful ablation pre- vs. post-ablation.

CONCLUSIONS

Patients with frequent PVCs and low-normal LV EF compared to patients with frequent PVCs and high-normal LV EF have evidence of PVC-induced cardiomyopathy and may benefit from ablation despite a preserved left ventricular EF.

Intramural Mapping of Intramural Septal Ventricular Arrhythmias

Background

Intramural ventricular arrhythmias (VAs) can originate in patients with or without structural heart disease. Electrogram (EGM) recordings from intramural sources of VA have not been described thoroughly.

Objective

We hypothesized that the presence of scar may be linked to the site of origin (SOO) of focal, intramural VAs.

Methods

In a series of 21 patients (age: 55 ± 11 years, 12 women, mean ejection fraction 43 ± 14%) in whom the SOO of intramural VAs was identified, we analyzed bipolar EGM characteristics at the SOO and compared the findings with the endocardial breakout site. The patients were from a pool of 86 patients with intramural VAs referred for ablation.

Results

In 16/21 patients intramural scarring was detected by cardiac magnetic resonance (CMR) imaging In patients in whom the intramural SOO was reached, intramural bipolar EGMs showed a lower voltage and had broader EGMs compared to the endocardial breakout sites (0.97 ± 0.56 vs. 2.28 ± 0.15 mV, p = .001; and 122.3 ± 31.6 vs. 96.5 ± 26.3 ms, p < .01). All intramural sampled sites at the SOO had either low voltage or broad abnormal EGMs. The activation time was significantly earlier at the intramural SOO than at breakout sites (−36.2 ± 11.8 vs. −23.2 ± 9.1 ms, p < .0001).

Conclusions

Sites of origin of intramural VAs with scar by CMR display EGM characteristics of scarring, supporting that scar tissue localizes to the SOO of intramural outflow tract arrhythmias in some patients. Scarring identified by CMR may be helpful in planning ablation procedures in patients with suspected intramural VAs.

Factors predictive for delayed enhancement in cardiac resonance imaging in patients undergoing catheter ablation of premature ventricular complexes

Background

Patients undergoing ablation of premature ventricular complexes (PVCs) can have cardiac scar. Risk factors for the presence of scar are not well defined.

Objectives

To determine the prevalence of scarring detected by delayed enhancement cardiac magnetic resonance imaging (DE-CMR) in patients undergoing ablation of PVCs, to create a risk score predictive of scar, and to explore correlations between the scoring system and long-term outcomes.

Methods

DE-CMR imaging was performed in consecutive patients with frequent PVCs referred for ablation. The full sample was used to develop a prediction model for cardiac scar based on demographic and clinical characteristics, and internal validation of the prediction model was done using bootstrap samples.

Results

The study consisted of 333 patients (52% male, aged 53.2 ± 14.5 years, preablation ejection fraction 50.9% ± 12.2%, PVC burden 20.7 ± 13.14), of whom 112 (34%) had DE-CMR scarring. Multiple logistic regression analysis showed age (odds ratio [OR] 1.02 [1.01–1.04]/year, P = .019) and preablation ejection fraction (OR 0.92 [0.89–0.94]/%, P < .001) to be predictive of scar. A weighted risk score incorporating age and ejection fraction was used to stratify patients into low-, medium-, and high-risk groups. Scar prevalence was around 86% in the high-risk group and 12% in the low-risk group; high-risk patients had worse survival free of arrhythmia.

Conclusions

Cardiac scar was present in one-third of patients referred for PVC ablation. A weighted risk score based simply on patient age and preprocedural ejection fraction can help discriminate between patients at high and low risk for the presence of cardiac scar and worse arrhythmia outcomes.