Acute failure of catheter ablation for ventricular tachycardia due to structural heart disease: causes and significance

Abstract

Background: Acute end points of catheter ablation for ventricular tachycardia (VT) remain incompletely defined. The aim of this study is to identify causes for failure in patients with structural heart disease and to assess the relation of this acute outcome to longer-term management and outcomes.

Methods and results: From 2002 to 2010, 518 consecutive patients (84% male, 62 ± 14 years) with structural heart disease underwent a first ablation procedure for sustained VT at our institution. Acute ablation failure was defined as persistent inducibility of a clinical VT. Acute ablation failure was seen in 52 (10%) patients. Causes for failure were: intramural free wall VT in 13 (25%), deep septal VT in 9 (17%), decision not to ablate due to proximity to the bundle of His, left phrenic nerve, or a coronary artery in 3 (6%), and endocardial ablation failure with inability or decision not to attempt to access the epicardium in 27 (52%) patients. In multivariable analysis, ablation failure was an independent predictor of mortality (hazard ratio 2.010, 95% CI 1.147 to 3.239, P=0.004) and VT recurrence (hazard ratio 2.385, 95% CI 1.642 to 3.466, P<0.001).

Conclusions: With endocardial or epicardial ablation, or both, acute ablation failure was seen in 10% of patients, largely due to anatomic factors. Persistence of a clinical VT is associated with recurrence and comparatively higher mortality.

Keywords: catheter ablation; failure; outcome; structural heart disease; ventricular tachycardia.

Figures

Figure 1.

Flow chart and causes of ablation failure. After endocardial mapping, 101 (23%) had failed ablation. Epicardial mapping was performed in 64 patients, which resulted in acute procedural success in an additional 49 patients. Thus, 52 (12%) were acute failures. ENDO indicates endocardial; EPI, epicardial; VT, ventricular tachycardia.

Figure 2.

Example of septal origin. (A) Merged RV and LV activation maps of VT indicating the earliest activation during VT is located at the mid septum. (B) Sustained monomorphic VT with a cycle length of 540 ms is present. The first 2 beats of a train of stimuli at a cycle length of 490 ms is shown. The VT is continually reset without an alteration in the QRS morphology consistent with entrainment with concealed fusion. The stimulus‐to‐QRS interval is 60 ms. As shown in the last beat of the tracing, the electrocardiogram onset at the recording site occurs 60 ms before the QRS onset. Thus, the stimulus‐to‐QRS interval matches the electrocardiogram‐to‐QRS interval. The postpacing interval matches the VT cycle length of 540 ms. These findings are consistent with pacing at a reentry circuit site near an “exit”. ABLd indicates bipolar intracardiac recordings from the distal electrode pair of the mapping catheter at left ventricular site; ABLp, those from the proximal pair; RV, right ventricle; LV, left ventricle; VT, ventricular tachycardia; Uni, unipolar recordings; d, distal; m, middle; p, proximal.

Figure 3.

Overall attributed causes of ablation failure are shown.

Figure 4.

Kaplan–Meier curves showing all cause mortality in the patients with ablation success, those with ablation failure, and those who did not have a postablation attempt to reinduce VT. All 518 patients were included in this survival analysis. In pairwise comparison, Bonferroni adjusted P<0.05/3 was considered significant. VT indicates ventricular tachycardia.

Figure 5.

Kaplan–Meier curves showing VT recurrence within 1 year after catheter ablation in the patients with ablation success, those with ablation failure and those who did not have a post ablation attempt to re‐induce VT. All 518 patients were included in this survival analysis. In pairwise comparison, Bonferroni adjusted P<0.05/3 was considered significant. VT indicates ventricular tachycardia.

Figure 6.

Kaplan–Meier curves showing all cause mortality in the patients with mappable VT only and those with at least 1 unmappable VT. All 518 patients were included in this survival analysis. P value is from the log‐rank test. VT indicates ventricular tachycardia.

Figure 7.

Kaplan–Meier curves showing VT recurrence within 1 year after catheter ablation in the patients with mappable VT only and those with at least 1 unmappable VT. All 518 patients were included in this survival analysis. P value is from the log‐rank test. VT indicates ventricular tachycardia.