Heart Rhythm UK position statement on clinical indications for implantable cardioverter defibrillators in adult patients with familial sudden cardiac death syndromes.

Whilst the decision regarding defibrillator implantation in a patient with a familial sudden cardiac death syndrome is likely to be most significant for any particular individual, the clinical decision-making process itself is complex and requires interpretation and extrapolation of information from a number of different sources. This document provides recommendations for adult patients with the congenital Long QT syndromes, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, hypertrophic cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. Although these specific conditions differ in terms of clinical features and prognosis, it is possible and logical to take an approach to determining a threshold for implantable cardioveter-defibrillator implantation that is common to all of the familial sudden cardiac death syndromes based on estimates of absolute risk of sudden death.

Paced ventricular electrogram fractionation predicts sudden cardiac death in hypertrophic cardiomyopathy.

AIMS: Paced electrogram fractionation analysis (PEFA) has been assessed for the prediction of sudden cardiac death (SCD) in a large-scale, prospective study of patients with hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: We determined the positive predictive value (PPV) of PEFA in relation to other risk factors for SCD and outcomes in 179 patients with HCM and no prior history of cardiac arrest. Patients were followed over a mean 4.3 years (range: 1.1-6.3 years). Thirteen patients had SCD-equivalent events: four of these patients died suddenly, three were resuscitated from ventricular fibrillation (VF), and six had implantable cardioverter-defibrillator (ICD) discharges in response to VF. PEFA identified nine of these patients and another 14 non-VF patients yielding a censored PPV of between 0.19 and 0.59 that was greater than the PPV that was the formal stopping point of the trial (0.18). Eighty per cent of patients were followed for 4 years or more. The PPV for the identification of SCD in this group was 0.38 (0.17-0.59). The use of two or more conventional markers to predict SCD identified five patients with SCD-equivalent events in the 4-year follow-up group and 42 other patients without events yielding a PPV of 0.106 (confidence limits 0.02-0.15). CONCLUSION: PEFA identifies HCM patients at risk of SCD with greater accuracy than non-invasive techniques and may have an important role in determining indications for ICD prescription.

A streamlined "3-catheter" approach in the electrophysiological study and radiofrequency ablation of narrow complex tachycardia.

BACKGROUND: Electrophysiological study (EPS) followed by radiofrequency (RF) ablation has emerged as the treatment of choice for symptomatic narrow complex tachycardia (NCT), for which purpose, 5 catheters are typically used (4 for the initial EPS and an additional one for the subsequent RF ablation). We describe an alternative, streamlined approach using only 3 catheters [2 standard (diagnostic) and 1 deflectable, thermistor tip (mapping)] as the standard configuration for EPS and RF ablation in patients with NCT but no pre-excitation on ECG. METHODS AND RESULTS: Diagnosis was obtained in all 250 consecutive patients (mean age 45 years, 174 females): atrio-ventricular nodal re-entrant tachycardia (AVNRT) in 188 (75%), concealed accessory pathways (AP's) in 38 patients (15%), ectopic atrial tachycardia in 19 patients (8%), persistent junctional re-entrant tachycardia (PJRT) in 4 patients (2%) and atrial fibrillation in 1 patient. An additional diagnostic catheter was used for optimising atrial pacing in 3 patients and for ventricular pacing in concealed right postero-septal AP's in another 3. An additional mapping catheter was used in 31 patients with concealed left-sided AP's, 2 with multiple AP's and 1 with PJRT. Three patients had complications (1 pulmonary embolism, 1 pericardial effusion and 1 atrio-ventricular node block). Overall, the immediate success rate was 98% (224/229) with a recurrence rate of 4.4% (10/224), and the total success rate (with repeat RF ablation if necessary) was 99.2% (227/229) over a median follow-up period of 31.4 months. The average cost saving was US$474 per procedure. Procedure duration (2.0 +/- 0.1 hours), fluoroscopy time (13 +/- 1 minutes) and the number of radiofrequency applications (5.4 +/- 0.3) also compared favourably with values reported in the literature for RF ablation of AVNRT. CONCLUSION: Compared to the conventional 5-catheter configuration for the combined EPS and RF ablation procedure in treatment of patients with NCT, the described 3-catheter configuration reduces cost, procedure duration and fluoroscopy time without compromising on success rate and safety. On these bases, we advocate its widespread adoption.

Noninvasive assessment of atrial substrate change after wide area circumferential ablation: a comparison with segmental pulmonary vein isolation.

BACKGROUND: The wide area circumferential ablation (WACA) approach to atrial fibrillation is thought to result in 'substrate modification' perhaps related to autonomic denervation. We examined this prospectively by comparing WACA and segmental pulmonary vein isolation (PVI) using noninvasive surrogate markers. METHODS: Heart rate variability (HRV) and signal averaged P wave (SAPW) data were derived from high-resolution (HR) recordings ('SpiderView' ELA Medical) made in sinus rhythm immediately before and 24 hours after ablation. RESULTS: Forty patients recruited (20 WACA; 20 PVI); cohorts were comparable. WACA caused marked SAPW change: P wave duration (PWD) (149[4.6] ms to 160[5.9] ms; P = 0.003), root mean square (RMS) (4.4[0.4]microV to 2.8[0.4]; P = 0.001) and energy content (30-150 Hz; 20.4 [3.6]microV(2)/s to 13.7[2.4]; P = 0.001). No significant change was seen after PVI. Heart rate increased after WACA and PVI (61.4 to 73.5 [P = 0.001]; 69.5 to 75.0 [P = 0.07], respectively). HRV was significantly influenced after WACA: low frequency power (LF) 5.7(0.4) to 3.6(0.4); P = 0.001), high-frequency power (HF) 4.6(0.4)-3.4(0.3); P = 0.024, and after PVI: LF 5.4(0.3) to 4.3(0.3); P = 0.024. HF: 4.4(0.4) to 3.0(0.4); P = 0.018). CONCLUSIONS: HR recordings exhibit change in HRV after WACA and PVI. Marked change in both HRV and SAPW is observed after WACA. SAPW variables provide a measure of atrial substrate change after WACA unrelated to autonomic denervation.