Prognostic Value of Nonischemic Ringlike Left Ventricular Scar in Patients With Apparently Idiopathic Nonsustained Ventricular Arrhythmias.

BACKGROUND: Left ventricular (LV) scar on late gadolinium enhancement (LGE) cardiac magnetic resonance has been correlated with life-threatening arrhythmic events in patients with apparently idiopathic ventricular arrhythmias (VAs). We investigated the prognostic significance of a specific LV-LGE phenotype characterized by a ringlike pattern of fibrosis. METHODS: A total of 686 patients with apparently idiopathic nonsustained VA underwent contrast-enhanced cardiac magnetic resonance. A ringlike pattern of LV scar was defined as LV subepicardial/midmyocardial LGE involving at least 3 contiguous segments in the same short-axis slice. The end point of the study was time to the composite outcome of all-cause death, resuscitated cardiac arrest because of ventricular fibrillation or hemodynamically unstable ventricular tachycardia and appropriate implantable cardioverter defibrillator therapy. RESULTS: A total of 28 patients (4%) had a ringlike pattern of scar (group A), 78 (11%) had a non-ringlike pattern (group B), and 580 (85%) had normal cardiac magnetic resonance with no LGE (group C). Group A patients were younger compared with groups B and C (median age, 40 vs 52 vs 45 years; P<0.01), more frequently men (96% vs 82% vs 55%; P<0.01), with a higher prevalence of family history of sudden cardiac death or cardiomyopathy (39% vs 14% vs 6%; P<0.01) and more frequent history of unexplained syncope (18% vs 9% vs 3%; P<0.01). All patients in group A showed VA with a right bundle-branch block morphology versus 69% in group B and 21% in group C (P<0.01). Multifocal VAs were observed in 46% of group A patients compared with 26% of group B and 4% of group C (P<0.01). After a median follow-up of 61 months (range, 34-84 months), the composite outcome occurred in 14 patients (50.0%) in group A versus 15 (19.0%) in group B and 2 (0.3%) in group C (P<0.01). After multivariable adjustment, the presence of LGE with ringlike pattern remained independently associated with increased risk of the composite end point (hazard ratio, 68.98 [95% CI, 14.67-324.39], P<0.01). CONCLUSIONS: In patients with apparently idiopathic nonsustained VA, nonischemic LV scar with a ringlike pattern is associated with malignant arrhythmic events.

Noninvasive Programmed Ventricular Stimulation-Guided Management Following Ventricular Tachycardia Ablation.

OBJECTIVES: This study sought to determine the impact of repeat catheter ablation (CA) prior to hospital discharge based on inducibility of clinical ventricular tachycardia (VT) during noninvasive programmed ventricular stimulation (NIPS). BACKGROUND: Inducibility of clinical VT during NIPS performed several days after CA identifies patients at high risk of recurrence. The impact of NIPS-guided repeat CA has not been reported. METHODS: Consecutive patients with structural heart disease undergoing CA of VT followed by NIPS were studied. Clinical VT was defined by comparison with 12-lead electrocardiograms and stored implantable cardioverter-defibrillator electrograms from spontaneous VT episodes. Among those with inducible clinical VT at NIPS, VT-free survival was compared between those in whom ablation was repeated (group 1) versus those in whom ablation was not repeated (group 2) prior to hospital discharge. RESULTS: Among 469 patients (64 ± 12 years of age; 85% males; 60% ischemic), 216 patients (46%) underwent NIPS 3 days (interquartile range: 2 to 4 days) after CA. Clinical VT was induced in 45 patients (21%). Among those 45, CA was repeated in 11 patients (24%). There were no significant differences in baseline clinical or index CA characteristics between groups 1 and 2. Over a median 36-month follow-up, only 1 patient (9%) in group 1 experienced VT recurrence compared to 24 patients (71%) in group 2 (p < 0.01). In univariate Cox regression, repeat CA guided by NIPS (hazard ratio: 0.07; 95% confidence interval: 0.01 to 0.58; p = 0.01) was the only predictor of VT-free survival. CONCLUSIONS: In patients with inducible clinical VT during post-ablation NIPS, repeat CA was associated with significantly lower risk of subsequent recurrence.

Long-Term Outcome of Catheter Ablation for Treatment of Bundle Branch Re-Entrant Tachycardia.

OBJECTIVES: This study reports the long-term outcome of patients with bundle branch re-entrant tachycardia (BBRT) who underwent catheter ablation for ventricular tachycardia (VT). BACKGROUND: BBRT is an uncommon mechanism of VT. Data on long-term outcomes of patients with BBRT treated with catheter ablation are insufficient. METHODS: Between 2005 and 2016, 32 patients had a sustained VT due to a bundle branch re-entrant mechanism. Diagnosis of BBRT was established per standard published criteria. RESULTS: The mode of presentation was syncope in 17 patients (53%) and palpitations in 15 (47%). BBRT was inducible in all subjects, and successful ablation of the right bundle branch in 19 patients (59%) or the left bundle branch in 13 patients (41%) was performed. During follow-up of 95 ± 36 months, 6 patients (19%) died, 3 of progressive heart failure and 3 of noncardiac causes. Recurrent VT due to BBRT did not occur in any patient. At baseline, 25 patients (78%) had a prolonged HV interval (>55 ms) and 7 (22%) had a normal HV interval (≤55 ms). In patients with a normal HV interval, there was only 1 death (due to malignancy), and no one developed heart block during 90 ± 36 months of follow-up. Ten patients (31%) had normal left ventricular (LV) function (LV ejection fraction ≥50%), and 22 (69%) had depressed LV function (LV ejection fraction <50%). No deaths were recorded in patients with normal LV function (5 with no implantable cardioverter-defibrillator) compared with 6 deaths among patients with depressed LV function (n = 22; p = 0.07). CONCLUSIONS: Radiofrequency ablation of the bundle branch is an effective therapy for treatment of BBRT. Sustained BBRT can be seen in patients with normal LV systolic function and HV interval with excellent long-term outcomes after ablation.