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Background: The early repolarization (ER) pattern is associated with an increased risk of arrhythmogenic sudden death. However, strategies for risk stratification of patients with the ER pattern are not fully defined., Objectives: This study sought to determine the role of electrophysiology studies (EPS) in risk stratification of patients with ER syndrome., Methods: In a multicenter study, 81 patients with ER syndrome (age 36 ± 13 years, 60 males) and aborted sudden death due to ventricular fibrillation (VF) were included. EPS were performed following the index VF episode using a standard protocol. Inducibility was defined by the provocation of sustained VF. Patients were followed up by serial implantable cardioverter-defibrillator interrogations., Results: Despite a recent history of aborted sudden death, VF was inducible in only 18 of 81 (22%) patients. During follow-up of 7.0 ± 4.9 years, 6 of 18 (33%) patients with inducible VF during EPS experienced VF recurrences, whereas 21 of 63 (33%) patients who were noninducible experienced recurrent VF (p = 0.93). VF storm occurred in 3 patients from the inducible VF group and in 4 patients in the noninducible group. VF inducibility was not associated with maximum J-wave amplitude (VF inducible vs. VF noninducible; 0.23 ± 0.11 mV vs. 0.21 ± 0.11 mV; p = 0.42) or J-wave distribution (inferior, odds ratio [OR]: 0.96 [95% confidence interval (CI): 0.33 to 2.81]; p = 0.95; lateral, OR: 1.57 [95% CI: 0.35 to 7.04]; p = 0.56; inferior and lateral, OR: 0.83 [95% CI: 0.27 to 2.55]; p = 0.74), which have previously been demonstrated to predict outcome in patients with an ER pattern., Conclusions: Our findings indicate that current programmed stimulation protocols do not enhance risk stratification in ER syndrome., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: This multicenter study sought to evaluate the long-term follow-up of patients ablated for idiopathic ventricular fibrillation (VF)., Background: Catheter ablation of idiopathic VF that targets ventricular premature beat (VPB) triggers has been shown to prevent VF recurrences on short-term follow-up., Methods: From January 2000, 38 consecutive patients from 6 different centers underwent ablation of primary idiopathic VF initiated by short coupled VPB. All patients had experienced at least 1 documented VF, with 87% having experienced > or =2 VF episodes in the preceding year. Catheter ablation was guided by activation mapping of VPBs or pace mapping during sinus rhythm., Results: There were 38 patients (21 men) age 42 +/- 13 years, refractory to a median of 2 antiarrhythmic drugs. Triggering VPBs originated from the right (n = 16), the left (n = 14), or both (n = 3) Purkinje systems and from the myocardium (n = 5). During a median post-procedural follow-up of 63 months, 7 (18%) of 38 patients experienced VF recurrence at a median of 4 months. Five of these 7 patients underwent repeat ablation without VF recurrence. Survival free of VF was predicted only by transient bundle-branch block in the originating ventricle during the electrophysiological study (p < 0.0001). The number of significant events (confirmed VF or aborted sudden death) was reduced from 4 (interquartile range 3 to 9) before to 0 (interquartile range 0 to 4) after ablation (p = 0.01)., Conclusions: Ablation for idiopathic VF that targets short coupled VPB triggers is associated with a long-term freedom from VF recurrence.

Objectives: This study was designed to compare electroanatomic mapping (EAM) and magnetic resonance imaging (MRI) with delayed contrast enhancement (DCE) data for delineation of post-infarct scars., Background: Electroanatomic substrate mapping is an important step in the post-infarct ventricular tachycardia (VT) ablation strategy, but this technique has not yet been compared with a gold-standard noninvasive tool informing on the topography and transmural extent of myocardial scars in humans., Methods: Ten patients (9 men, age 71 +/- 10 years) admitted for post-infarct VT ablation underwent both a left ventricle DCE MRI and a sinus-rhythm 3-dimensional (3D) (CARTO) EAM (Biosense Webster, Johnson & Johnson, Diamond Bar, California). A 3D color-coded MRI-reconstructed left ventricular endocardial shell was generated to display scar data (intramural location and transmural extent). A matching process allocated any CARTO point to its corresponding position on the MRI map. Electrogram (EGM) characteristics were then evaluated in relation to scar data., Results: A spiky EGM morphology, a reduced unipolar or bipolar EGM voltage amplitude (<6.52 and <1.54 mV, respectively), as well as a longer bipolar EGM duration (>56 ms) independently correlated with the presence of scar whatever its intramural position. Endocardial scars had a larger degree of signal reduction than intramural or epicardial scars. None of the parameters was correlated with transmural scar depth. A clear mismatch in infarct surface between CARTO and MRI maps was observed in one-third of infarct zones., Conclusions: Sinus-rhythm EAM helps identify the limits of post-infarct scars. However, the accuracy of EAM for precise scar delineation is limited. This limit might be circumvented using anatomical information provided by 3D MRI data.

Objectives: This study sought to determine whether the reopening of the infarct-related vessel is related to clinical characteristics or cardiovascular risk factors, or both., Background: In acute myocardial infarction, thrombolytic therapy reduces mortality by restoring the patency of the infarct-related vessel. However, despite the use of thrombolytic agents, the infarct-related vessel remains occluded in up to 40% of patients., Methods: We studied 295 consecutive patients with an acute myocardial infarction who underwent coronary angiography within 15 days (mean [+/- SD] 6.7 +/- 3.2 days) of the onset of symptoms. Infarct-related artery patency was defined by Thrombolysis in Myocardial Infarction trial flow grade > or = 2. Four cardiovascular risk factors--smoking, hypertension, hypercholesterolemia and diabetes mellitus--and eight different variables-age, gender, in-hospital death, history of previous myocardial infarction, location of current myocardial infarction, use of thrombolytic agents, time interval between onset of symptoms, thrombolytic therapy and coronary angiography--were recorded in all patients., Results: Thrombolysis in current smokers and anterior infard location on admission were the three independent factors highly correlated with the patency of the infarct-related vessel (odds ratios 3.2, 3.0 and 1.9, respectively). In smokers, thrombolytic therapy was associated with a higher reopening rate of the infard vessel, from 35% to 77% (p < 0.001). Nonsmokers did not benefit from thrombolytic therapy, regardless of infarct location., Conclusions: These observational data, if replicated, suggest that in patients with acute myocardial infarction, thrombolytic therapy may be most effective in current smokers, whereas nonsmokers and ex-smokers may require other management strategies, such as emergency percutaneous transluminal coronary angioplasty.

Objectives: This study was designed to assess the influence of accessory atrioventricular (AV) pathway location on the clinical and electrophysiologic characteristics of 384 consecutive symptomatic patients having a single accessory pathway., Methods: Four locations were studied: left free wall (n = 270), posteroseptal (n = 52), anteroseptal (n = 29) and right free wall (n = 33). Ten clinical variables and 12 electrophysiologic variables were analyzed, including the effective refractory period of the accessory pathway and the different clinically occurring and inducible arrhythmias., Results: Only two clinical findings were associated with accessory pathway location: 1) later age at onset of symptoms in the left free wall versus other accessory pathway locations (24 +/- 12 vs. 20 +/- 11 years, p = 0.02), and 2) later age at the time of electrophysiologic study in the left free wall accessory pathway location (36 +/- 13 vs. 32 +/- 11 years, p = 0.01). Six electrophysiologic variables showed a correlation with the accessory pathway location: 1) retrograde conduction only was found less frequently in right free wall (9%) and anteroseptal (10%) than in left free wall (26%) and posteroseptal (29%) accessory pathway locations (p = 0.05); 2) the retrograde effective refractory period of the accessory pathway was shorter in anteroseptal (253 +/- 52 ms) and left free wall (270 +/- 72 ms) as compared with right free wall (296 +/- 101 ms) and posteroseptal (301 +/- 76 ms) locations (p = 0.05); 3) retrograde decremental conduction over the accessory pathway was present in the posteroseptal (17%) and left free wall (3%) but absent in the other locations (p less than 0.001); 4) anterograde decremental conduction was only seen in the right free wall location (12%) (p less than 0.001); 5) orthodromic reentrant tachycardia was induced less frequently in the right free wall than in other locations (70% vs. 93%, p less than 0.001); and 6) inducibility of atrial fibrillation was greater in anteroseptal (62%) than in right free wall (21%), left free wall (44%) and posteroseptal (36%) locations (p = 0.01)., Conclusions: The location of the accessory AV pathway is associated with specific electrophysiologic characteristics.

To determine the natural history of late potentials on the signal-averaged electrocardiogram (ECG), multivariate analysis was performed in 167 patients (138 men, 29 women) with a first anterior or inferior acute myocardial infarction. Seventy-four patients received thrombolytic therapy; the remaining 93 patients were treated conventionally. All patients underwent coronary angiography, left ventricular ejection fraction determination and signal-averaged ECG recording. Eight variables thought to be correlated with the presence of late potentials were studied; that is, age, infarct location, number of diseased coronary vessels, left ventricular ejection fraction, infarct-related coronary artery patency, treatment received, delay between admission and signal-averaged recording and delay between admission and coronary angiography. Statistical analysis showed that two independent factors (coronary artery occlusion and impaired left ventricular ejection fraction) were highly correlated with the incidence of late potentials. The occurrence of late potentials was multiplied by 5 in case of an occluded infarct-related vessel and by 1.75 each time the left ventricular ejection fraction value decreased by 0.10. This study suggests that coronary artery patency is the most important factor that decrease the rate of late potentials after a first acute myocardial infarction and it occurs independently of infarct location and left ventricular function.