Stereotactic ablative radiotherapy in patients with refractory ventricular tachyarrhythmia.

Stereotactic ablative body radiotherapy (SABR) is an innovative therapeutic approach in patients (pts) with a diagnosis of refractory ventricular tachyarrhythmia (VT) after the use of drugs, radiofrequency catheter ablation, and/or defibrillator (ICD) implant. The current efficacy data of SABR are limited and several prospective clinical studies are ongoing to support the use of ablative radiation dose to control VT. The aim of the current prospective pilot study is to report the efficacy and tolerability of SABR in ICD implanted pts with refractory VT in our centre. Non-invasive electroanatomical mapping (EAM), cardiac computed tomography (CT), and 18F-fluorodeoxyglucose positron emission (FDG-PET)-CT scan were used and combined with a radiation CT scan. A dose prescription of 25 Gy in a single dose was delivered by volumetric modulated arc therapy (VMAT) Linac-based. The primary endpoint was efficacy, defined as a reduction in ICD shocks after SABR treatment, while the secondary endpoint was safety. Six consecutive pts (five males and one female) implanted with an ICD and with three or more VT were enrolled. One pts died after 1 month, due to end-stage heart failure. Two pts experienced ICD shocks in VT 2 and 5 months after treatment. Three pts experienced no more ICD shocks on VT after therapy. Our data suggest the efficacy and safety of SABR treatment in pts with VT. Larger dataset of pts and longer follow-up are otherwise required to validate the impact of SABR as a standardized treatment in these pts.

Epicardial adipose tissue, pulmonary veins anatomy, and the P-wave/PR interval ratio in young patients with atrial fibrillation.

Background: Atrial fibrillation (AF) is uncommon in the youngest population. Epicardial adipose tissue (EAT) volume has been proposed as an independent AF risk factor. Objective: The aim of this retrospective study was to evaluate the impact of the EAT, the anatomy of the pulmonary veins (PVs), and electrocardiogram (ECG) features in these young patients with AF. Methods: Sixty-two patients divided in 2 groups, one with history of paroxysmal AF treated with ablation and the other, a control group, all younger than 30 years of age, were included. Computed tomography scans were performed in both groups to estimate the PVs anatomy and EAT volume. Twelve-lead ECGs were performed in all patients. Patients underwent follow-up in our outpatient clinic (35.9 ± 18.3 months). Results: In the AF group, the EAT volume around the left atrium was 22.25 ± 9.3 cm3 compared with 12.61 ± 3.37 cm3, showing a statistically significance difference (P = .003). Family history resulted to be another significant risk factor (P = .009). During follow-up, 67.7% of the patients treated were still free of events. The anatomy and morphology of the right-sided PVs seemed to play a more consistent role in the patients with AF recurrences (P = .04). The P/PR ratio, a new ECG index, seemed predict AF recurrences after ablation (P = .03). Conclusion: The abundance of EAT seems related to the risk of developing AF in young patients. The recurrence of AF is about 33% and does not seem related to the EAT volume, but rather to the anatomy of the PVs. A higher P/PR ratio might suggest recurrences.

Voltage mapping of Koch's triangle in atrioventricular nodal reentrant tachycardia ablation : Results from an observational multicenter prospective registry.

BACKGROUND: The identification of a "low-voltage bridge" to guide ablation of atrioventricular nodal reentry tachycardia (AVNRT) has been described as a safe and effective strategy in children. We investigated the presence of a low-voltage bridge in adult patients undergoing AVNRT ablation, to evaluate its anatomical correspondence with the successful ablation site. We also investigated the possible correlations between Koch's triangle anatomy and patients' biometric characteristics. METHODS: This observational registry prospectively collected data from 200 patients undergoing AVNRT ablation, guided by 3D electroanatomical mapping system, in 6 electrophysiology centers. Koch's triangle voltage map was collected; then, the anatomical correspondence between the low-voltage bridge and the successful ablation site was evaluated. Koch's triangle anatomical dimensions were subsequently drawn from the mapping system and correlated to patients' gender, age, and weight. RESULTS: The low-voltage bridge was identified in 159 over 200 procedures (79.5%). When the low-voltage bridge was identified, its anatomical correspondence with the successful ablation site has been proved in 137 over 159 cases (86%), with a reduction of radiofrequency deployment time. No strict correlations were found, on the other side, between Koch's triangle anatomy and patients' biometric data. CONCLUSIONS: The identification of the low-voltage bridge has proved to be a helpful strategy to guide AVNRT ablation in a large cohort of adult patients. Targeting the low-voltage bridge during AVNRT ablation helps to reduce RF application time. Koch's triangle morphological characteristics cannot be predicted on the base of patients' biometric data.

Individualized ablation strategy to treat persistent atrial fibrillation: Core-to-boundary approach guided by charge-density mapping.

BACKGROUND: Noncontact charge-density mapping allows rapid real-time global mapping of atrial fibrillation (AF), offering the opportunity for a personalized ablation strategy. OBJECTIVE: The purpose of this study was to compare the 2-year outcome of an individualized strategy consisting of pulmonary vein isolation (PVI) plus core-to-boundary ablation (targeting the conduction pattern core with an extension to the nearest nonconducting boundary) guided by charge-density mapping, with an empirical PVI plus posterior wall electrical isolation (PWI) strategy. METHODS: Forty patients (age 62 ± 12 years; 29 male) with persistent AF (10 ± 5 months) prospectively underwent charge-density mapping-guided PVI, followed by core-to-boundary stepwise ablation until termination of AF or depletion of identified cores. Freedom from AF/atrial tachycardia (AT) at 24 months was compared with a propensity score-matched control group of 80 patients with empirical PVI + PWI guided by conventional contact mapping. RESULTS: Acute AF termination occurred in 8 of 40 patients after charge-density mapping-guided PVI alone and in 21 of the remaining 32 patients after core-to-boundary ablation in the study cohort, compared with 8 of 80 (10%) in the control cohort (P <.001). On average, 2.2 ± 0.6 cores were ablated post-PVI before acute AF termination. At 24 months, freedom from AF/AT after a single procedure was 68% in the study group vs 46% in the control group (P = .043). CONCLUSION: An individualized ablation strategy consisting of PVI plus core-to-boundary ablation guided by noncontact charge-density mapping is a feasible and effective strategy for treating persistent AF, with a favorable 24-month outcome.

Should all individuals with a nondiagnostic Brugada-electrocardiogram undergo sodium-channel blocker test?

BACKGROUND: The diagnostic Brugada-electrocardiogram (Br-ECG) is characterized by "coved-type" ST-segment elevation (type 1) in V(1) to V(2)/V(3). The sodium-channel blocker test is clinically used to unmask diagnostic Br-ECG in patients with nondiagnostic "saddle-back" Br-ECG (type 2 and type 3). OBJECTIVE: To assess the prognostic value of the sodium-channel blockers test in individuals with a nondiagnostic Br-ECG. METHODS: We studied 153 consecutive patients (128 men; age 41.7 ± 14.0 years) with a type 2/3 Br-ECG who underwent a sodium-channel blocker test with either flecainide (48%) or ajmaline (52%). Nondiagnostic Br-ECGs were identified during the evaluation of cardiac arrest in 5 patients (3%), syncope in 36 (24%), cascade family screening in 48 (31%), and incidental ECG in 64 (42%). A spontaneous type 1 Br-ECG was systematically excluded by serial ECGs (6.1 ± 0.4) and recording of right precordial leads both at standard and second and third intercostal spaces. RESULTS: The sodium-channel blocker test result was positive in 76 (50%) patients. During a follow-up of 59 ± 33 months, 9 (5.9%) patients experienced events such as syncope (n = 4), appropriate interventions of defibrillator (n = 4), or sudden death (n = 1). A positive sodium-channel blocker test was associated with a significantly higher event rate in symptomatic patients (P = .01) but not in asymptomatic individuals (P = .18). No events occurred among asymptomatic individuals with an incidental nondiagnostic Br-ECG. CONCLUSIONS: In asymptomatic individuals with a nondiagnostic Br-ECG, the incidence of events is low regardless of the sodium-channel blocker test result while in symptomatic patients a positive sodium-channel blocker test result is associated with an adverse arrhythmic outcome and may contribute to risk stratification.

Age-related hemodynamic changes during vasovagal syncope.

OBJECTIVE: The aim of our study was to identify specific age-related hemodynamic changes during upright tilt test in patients with vasovagal syncope. METHODS: We studied 115 subjects who were referred to us for unexplained syncope during 65 degrees tilt with pharmacological challenge (s.l. nitrate) by noninvasive monitoring of blood pressure (Finometer). Two derived variables were also considered: total peripheral resistance and stroke volume. The patients were divided into 3 groups by age: Group 1, 10-30 yrs; Group 2, 31-50 yrs; and Group 3, >51 yrs. RESULTS: The test was positive in 65 patients (57%). During the first 20 min of the test, older patients experienced lower increases in heart rate (p<0.00001) and premature reduction of total peripheral resistance (p<0.005) and systolic blood pressure (p<0.005). Group 1 showed more pronounced decreases in stroke volume (p<0.01). No differences emerged between negative and positive patients. In the 5 min that preceded syncope, younger subjects experienced a distinct, transient increase in heart rate immediately before symptom onset (p<0.005). Blood pressure was prematurely and progressively decreased in Group 3, whereas it decreased only in the 90 s prior to syncope in Groups 1 and 2 (p<0.01). CONCLUSIONS: Our results suggest that blunted sympathetic activation occurs during passive orthostatism in older patients. On the other hand, hemodynamic changes before symptom onset seem to indicate as in younger subjects syncope results from an excessive sympathovagal reaction, whereas in older subjects it is related to an overwhelming, progressive central vagal activity that is associated with a defective peripheral sympathetic activation.