Background-There are limited data on typical arrhythmogenic substrates and associated ventricular tachycardias (VT) in patients with nonischemic cardiomyopathy. The substrate location may have implications for the ablation strategy. Methods and Results-Nineteen consecutive patients with nonischemic cardiomyopathy (age 58±14 years, 79% men, left ventricular ejection fraction 41±11%) who underwent contrast-enhanced MRI and VT ablation were included. On the basis of 3-dimensional contrast-enhanced MRI-derived scar reconstructions, 8 patients (42%) had predominant basal anteroseptal scar, 9 patients (47%) had predominant inferolateral scar, and 2 patients (11%) had other scar types. Three distinct VT morphologies (≥1 of 3 inducible in 16/19 patients) were associated with underlying scar type. In 9 patients with anteroseptal scar-related VT (8/9 predominant scar, 1/9 nonpredominant), ablation target sites (defined as sites with ≥11/12 pacemap, concealed entrainment or VT termination during ablation) were located in the aortic root and/or anteroseptal left ventricular endocardium in 8 patients (89%) and in the anterior cardiac vein in 1 patient (11%), with additional target sites at the right ventricular septum in 2 patients (22%) and at the epicardium in 1 patient (11%). In contrast, in 8 patients with predominant inferolateral scar-related VT, target sites were located at the epicardium in 5 patients (63%) and in the endocardial inferolateral left ventricle in 3 patients (37%). Conclusions-Two typical scar patterns (anteroseptal and inferolateral) account for 89% of arrhythmogenic substrates in patients with nonischemic cardiomyopathy. Three distinct VT morphologies are highly suggestive of the presence of these scars. Anteroseptal scars were, in general, most effectively approached from the aortic root or anteroseptal left ventricular endocardium, whereas inferolateral scars frequently required an epicardial approach. (Circ Arrhythm Electrophysiol. 2013;6:875-883.)

Both BV ≤ 1.81 mV and UV ≤ 7.95 mV are useful for detection of scar during epicardial EAM, in the absence of ≥ 2.8 mm fat. However, EC can be used to detect scar covered with fat. A newly developed algorithm combining UV and EC can differentiate between scar and viable myocardium. Unipolar voltage but not BV could detect intramural scar.

Background— Ablation failure and recurrence rates after ventricular tachycardia (VT) ablation in nonischemic cardiomyopathy are high and the optimal procedural end point is not well defined. This study assessed the outcome after ablation, the impact of noninducibility, and other potential predictors of VT recurrence. Methods and Results— Forty-five patients with nonischemic cardiomyopathy (60±16 years; left ventricular ejection fraction, 44±14%) accepted for VT ablation were included. Epicardial mapping was performed in 29 (64%). A median of 2 (first-to-third quartile, 2–4) VTs (cycle length, 342±77 ms) were induced per patient. After ablation, the complete programmed electric stimulation protocol (3 drive cycle length, 3 extrastimuli ≥200 ms, and burst≥2 sites) was repeated. Complete success (noninducibility of any monomorphic VT) was achieved in 17 patients (38%), partial success (elimination of clinical VT, persistent inducibility of nonclinical VT) in 17 patients (38%), and failure (persistent inducibility of clinical VT) in 11 patients (24%). During 25±15 months of follow-up, VT occurred in 24 patients (53%), but the 6-month VT burden was reduced by ≥75% in 79%. Recurrence rates were low after complete procedural success (18%), but high after both partial success (77%) and failure (73%). Non-complete procedural success was the strongest predictor of VT recurrence (hazard ratio, 8.20; 95% confidence interval, 2.37–28.43; P =0.001). Conclusions— Although 53% of patients had VT during follow-up, the 6-month VT burden was decreased by ≥75% in 79%. Recurrence rates are low after complete procedural success, but high after both partial success and failure. Non-complete procedural success was the strongest predictor of VT recurrence.

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Background-High idiopathic premature ventricular contractions (PVC) burden has been associated with PVC-induced cardiomyopathy. Patients may be symptomatic before left ventricular (LV) dysfunction develops. N-terminal pro-B-type natriuretic peptide (NT-proBNP) and circumferential end-systolic wall stress (cESS) on echocardiography are markers for increased ventricular wall stress. This study aimed to evaluate the relation between presenting symptoms, PVC burden, and increased ventricular wall stress in patients with frequent PVCs and preserved LV function. Methods and Results-Eighty-three patients (41 men; 49±15 years) with idiopathic PVCs and normal LV function referred for PVC ablation were included. Type of symptoms (palpitations, fatigue, and [near-]syncope), PVC burden on 24-hour Holter, NT-proBNP levels, and cESS on echocardiography were assessed before and 3 months after ablation. Sustained successful ablation was defined as ≥80% PVC burden reduction during follow-up. Patients were symptomatic for 24 months (Q1-Q3, 16-60); 73% reported palpitations, 47% fatigue, and 30% (near-)syncope. Baseline PVC burden was 23±13%, median NT-proBNP 92 pg/mL (Q1-Q3 50-156), and cESS 143±35 kdyne/cm 2 . Fatigue was associated with higher baseline NT-proBNP and cESS (P<0.001, P=0.011, respectively). After sustained successful ablation, achieved in 81%, NT-proBNP and cESS decreased significantly (P<0.001 and P=0.036, respectively). Fatigue was independently associated with a significantly larger reduction in NT-proBNP. In patients with nonsuccessful ablation, NT-proBNP and cESS remained unchanged. Conclusions-In patients with frequent PVCs and preserved LV function, fatigue was associated with higher baseline NT-proBNP and cESS, and with a significantly larger reduction in NT-proBNP after sustained successful ablation. These findings support a link between fatigue and PVC-induced increased ventricular wall stress, despite preserved LV function.