Endocardial Electrogram Characteristics of Epicardial Ventricular Arrhythmias

Patient Selection for Epicardial Ablation-Part I: The Role of Epicardial Ablation in Various Cardiac Disease States

Epicardial catheter ablation is most commonly performed following unsuccessful endocardial ablation. Given the frequency of epicardial substrates in certain cardiomyopathic disease states, however, a combined endocardial–epicardial approach should be considered as a primary treatment strategy. Although epicardial ablation is primarily deployed in patients with ventricular arrhythmias, the role of epicardial approaches in supraventricular tachycardias (eg, atrial fibrillation, inappropriate sinus tachycardia, and—rarely—accessory pathways) is growing, with continued advances being made.

Repeat ablation of refractory ventricular arrhythmias in patients with nonischemic cardiomyopathy: Impact of midmyocardial substrate and role of adjunctive ablation techniques

INTRODUCTION

Multiple ablations are often necessary to manage ventricular arrhythmias (VAs) in nonischemic cardiomyopathy (NICM) patients. We assessed characteristics and outcomes and role of adjunctive, nonstandard ablation in repeat VA ablation (RAbl) in NICM.

METHODS AND RESULTS

Consecutive NICM patients undergoing RAbl were analyzed, with characteristics of the last VA ablations compared between those undergoing 1 versus multiple-repeat ablations (1-RAbl vs. >1RAbl), and between those with or without midmyocardial substrate (MMS). VA-free survival was compared. Eighty-eight patients underwent 124 RAbl, 26 with > 1RAbl, and 26 with MMS. 1-RAbl and > 1-RAbl groups were similar in age (57 ± 16 vs. 57 ± 17 years; P = 0.92), males (76% vs. 69%; P = 0.60), LVEF (40 ± 17% vs. 40 ± 18%; P = 0.96), and amiodarone use (31% vs. 46%, P = 0.22). One-year VA freedom between 1-RAbl vs. > 1RAbl was similar (82% vs. 80%; P = 0.81); adjunctive ablation was utilized more in >1RAbl (31% vs. 11%, P = 0.02), and complication rates were higher (27% vs. 7%, P = 0.01), most due to septal substrate and anticipated heart block. >1-RAbl patients had more MMS (62% vs. 16%, P < 0.01). Although MMS was associated with worse VA-free survival after 1-RAbl (43% vs. 69%, P = 0.01), when >1RAbl was performed, more often with nonstandard ablation, VA-free survival was comparable to non-MMS patients (85% vs. 81%; P = 0.69). More RAbls were required in MMS versus non-MMS patients (2.00 ± 0.98 vs. 1.16 ± 0.37; P < 0.001).

CONCLUSION

For NICM patients with recurrent, refractory VAs despite previous ablation, effective arrhythmia control can safely be achieved with subsequent ablation, although >1 repeat procedure with adjunctive ablation is often required, especially with MMS.

Unipolar peak-negative voltage as an endocardial electrographic characteristic to predict overlying abnormal epicardial substrates in patients with right epicardial ventricular tachycardia

INTRODUCTION

The characteristics of endocardial electrograms needed to detect the overlying abnormal epicardial substrates in arrhythmogenic right ventricular cardiomyopathy with epicardial ventricular tachycardia (VT) remain unclear. This study investigated which of the endocardial electrogram characteristics could predict the overlying abnormal epicardial substrates.

METHODS AND RESULTS

In 20 consecutive patients (median age: 46 years, 11 men) undergoing epicardial VT ablation, detailed endocardial and epicardial mappings were obtained by using the CARTO 3 system. The endocardial electrographic characteristics (unipolar peak-to-peak voltage, unipolar peak-negative-voltage, bipolar voltage, and bipolar electrogram duration) of the opposite endocardium and epicardium in RV were retrospectively investigated (N = 1,697 paired points, 84 ± 60 pairs/patient). Endocardial predictors of the presence of epicardial dense scar (<0.5 mV), low voltage zones (LVZ; ≤1.5 mV), and ablation targets (by using activation mapping, entrainment mapping, and pace mapping) were analyzed.

RESULTS

In the multivariable analysis, (1) unipolar peak-negative voltage independently predicted the presence of epicardial LVZ, epicardial dense scar, and ablation targets; (2) bipolar voltage could not predict epicardial lesions; and (3) bipolar electrogram duration predicted epicardial LVZ, but not dense scar or ablation targets. The endocardial unipolar peak-negative voltage of <1.66 mV (89% sensitivity and 53% specificity) was the optimal cutoff point for predicting epicardial dense scar.

CONCLUSIONS

In patients with RV epicardial VT, the presence of unipolar peak-negative voltage of <1.66 mV in the endocardium predicted the presence of epicardial dense scar (<0.5 mV) and potential ablation targets in the overlying epicardium.