Histopathologic Effects of Endocardial and Epicardial Percutaneous Radiofrequency Catheter Ablation in Dilated Nonischemic Cardiomyopathy

Impact of recanalization of chronic total occlusion on left ventricular electrical remodeling

Background

Successful percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) is associated with reduction of cardiac mortality, as well as reducing fatal ventricular arrhythmias. The aim of this study was to evaluate the effect of recanalization of CTO on endocardial left ventricular voltages by paired electrophysiological studies.

Methods

Sixteen consecutive patients who underwent PCI for de novo CTO lesions were included. High‐density mapping was performed during sinus rhythm before and 8 months after PCI. According to the amplitude of bipolar electrograms, the left ventricular endocardium was classified into a preserved normal voltage (>1.5 mV), border zone (0.5–1.5 mV), and dense scar areas (<0.5 mV).

Results

The border zone area had a significant positive correlation with CTO length, as well as a significant negative correlation observed in the preserved voltage region. In the successful PCI patient, the median dense scar area did not change significantly (reported as [median difference: 95% confidence interval]) between baseline and after PCI (0.1 cm²: –2.8 to 2.9). However, the area of the border zone decreased (–10.5 cm²: –16.8 to –4.1) and the preserved voltage area increased significantly (19.2 cm²: 7.7–30.6). In addition, successful PCI was related to slight, but significant, increase in the amplitude of unipolar and bipolar voltage (1.55 mV: 0.88–3.33, 0.23 mV: 0.08–0.36).

Conclusions

Recanalization of CTO may promote reverse electrical remodeling in the border zone of the left ventricle, without affecting the dense scar tissue.

Pattern of late gadolinium enhancement predicts arrhythmic events in patients with non-ischemic cardiomyopathy

BACKGROUND

Left ventricular late gadolinium enhancement (LV-LGE) by cardiac magnetic resonance (CMR) imaging has been associated with adverse clinical outcomes in patients with non-ischemic cardiomyopathy (NICM). However, an association between the characteristics of the LGE and arrhythmic risk has not been demonstrated consistently. This study evaluated the impact of the LV-LGE characteristics on the arrhythmia risk in patients with NICM.

METHODS

This study enrolled 365 consecutive patients (54±15years) with NICM who underwent CMR imaging. All patients were monitored for the following outcomes: major arrhythmic events (MA), including sustained ventricular tachycardia, an appropriate implantable cardioverter-defibrillator intervention, ventricular fibrillation and sudden cardiac death.

RESULTS

During 44.3±36.4months of follow-up, 44 (12.1%) patients experienced MA. LV-LGE was observed in 40 (90.9%) and 221 (68.8%) patients with and without MA, respectively. LV-LGE was more frequently observed in the MA group (p=0.002). The age- and sex-adjusted hazard ratio (HR) of MA was increased in patients with LGE extent≥8% (HR 8.45, 95% confidence interval (CI) 2.91-24.6), and those with subendocardial (HR 6.98, 95% CI 1.74-28.0) and subepicardial LGE patterns (HR 7.2, 95% CI 1.61-35.6). In multivariable models adjusted for other clinical variables, only the subepicardial LGE pattern had 7.2 (95% CI, 1.61-32.6, p=0.01) time increase in the MA risk.

CONCLUSIONS

LV-LGE in patients with NICM is not uncommon. The subepicardial pattern of the LV-LGE was an independent predictor of MA, suggesting that specific patterns of the LV-LGE are closely related to the severity of arrhythmic events.

The Emerging Role of Epicardial Ablation

Sosa and colleagues first described a percutaneous approach (via the subxiphoid area) to access the pericardial space in 1996. Epicardial mapping and ablation is increasingly used for the treatment of supraventricular and ventricular arrhythmias and represents an adjunctive approach for challenging arrhythmias to improve procedural success rates. Epicardial ablation should be considered not only after the failure of an endocardial ablation but often as a first-line approach. Complications may occur during percutaneous access and epicardial ablation, and these might be reduced or avoided by improved operator skills and experience. New tools to access the epicardial space are being evaluated.

Epicardial ablation for ventricular tachycardia: a European multicenter study

BACKGROUND

The purpose of this study was to describe the epicardial percutaneous ablation experience of 6 European high-volume ventricular tachycardia (VT) ablation centers.

METHODS AND RESULTS

Data from 218 patients with coronary artery disease (CAD, n=85 [39.0%]), idiopathic dilated of patients with idiopathic VT cardiomyopathy (IDCM, n=67 [30.7%]), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARCD/C, n=13 [6%]), hypertrophic cardiomyopathy (HCM, n=5 [2.3%]), and absence of structural heart disease (n=48 [22%]) undergoing epicardial subxyphoid access for VT ablation were collected. The epicardial approach was attempted as first-line treatment in 78 patients (35.8%). Acute prevention of VT inducibility was obtained in 156 patients (71.6%). There were no procedure-related deaths. Cardiac tamponade occurred in 8 patients, and abdominal hemorrhage in 1 patient. Six patients died of electrical storm recurrence within 48 hours from the procedure. After a mean follow-up of 17.3±18.2 months, 60 patients (31.4%) presented with VT recurrence (39.3% of IDCM patients; 34.7% of CAD patients; 30.8% of ARVD/C patients; 25% of HCM patients; 17.1% of patients with idiopathic VT). Twenty patients (10.4%) died during follow-up (12 of heart failure, 2 of cardiac arrest, and 6 of extracardiac causes).

CONCLUSIONS

In experienced centers, epicardial ablation of VT has an acceptable risk and favorable outcome. In selected patients, it is reasonable to consider as a first-line ablation approach.

Ablation of epicardial right ventricular tachycardia provoked by proarrhythmic RV pacing in a patient with dilated cardiomyopathy

Ventricular arrhythmias are common in the setting of nonischemic dilated cardiomyopathy (NIDCM). However, the characterization of the substrate and mechanism of epicardial ventricular tachycardia (VT) associated with NIDCM is limited, and to the best of our knowledge VT due to myocardial reentry within the right ventricular (RV) epicardium associated with NIDCM has not been reported. We report a case of RV epicardial VT provoked by RV pacing that was successfully ablated.