Cryoballoon Ablation for Atrial Fibrillation

Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP) provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1) the rationale for adjunctive imaging, 2) selection of an appropriate cryoballoon size, 3) predictors of efficacy, 4) advanced trouble-shooting techniques, and 5) strategies to reduce procedural complications, such as phrenic nerve palsy

Predicting the entrainment of reentrant cardiac waves using phase resetting curves,” Phys

Excitable media, such as the Belousov-Zhabotinsky medium or the heart, are capable of supporting excitation waves that circulate in a closed repetitive path-a phenomenon known as reentrant excitation. A single stimulus, depending on its magnitude, timing, and location, can cause a time shift of the reentrant excitation called resetting. The present study examines the ability of resetting data to predict the effects of periodic stimuli on reentrant excitation circulating on an annular domain. We compare the results of the theoretical models with experiments carried out in an animal model of a dangerous reentrant cardiac rhythm. The current work may lead to improved approaches to therapy through a better understanding of how typical clinical stimuli interact with abnormal reentrant cardiac rhythms

Fish Oil for the Reduction of Atrial Fibrillation Recurrence, Inflammation, and Oxidative Stress

AbstractBackgroundRecent trials of fish oil for the prevention of atrial fibrillation (AF) recurrence have provided mixed results. Notable uncertainties in the existing evidence base include the roles of high-dose fish oil, inflammation, and oxidative stress in patients with paroxysmal or persistent AF not receiving conventional antiarrhythmic (AA) therapy.ObjectivesThe aim of this study was to evaluate the influence of high-dose fish oil on AF recurrence, inflammation, and oxidative stress parameters.MethodsWe performed a double-blind, randomized, placebo-controlled, parallel-arm study in 337 patients with symptomatic paroxysmal or persistent AF within 6 months of enrollment. Patients were randomized to fish oil (4 g/day) or placebo and followed, on average, for 271 ± 129 days.ResultsThe primary endpoint was time to first symptomatic or asymptomatic AF recurrence lasting >30 s. Secondary endpoints were high-sensitivity C-reactive protein (hs-CRP) and myeloperoxidase (MPO). The primary endpoint occurred in 64.1% of patients in the fish oil arm and 63.2% of patients in the placebo arm (hazard ratio: 1.10; 95% confidence interval: 0.84 to 1.45; p = 0.48). hs-CRP and MPO were within normal limits at baseline and decreased to a similar degree at 6 months (Δhs-CRP, 11% vs. −11%; ΔMPO, −5% vs. −9% for fish oil vs. placebo, respectively; p value for interaction = NS).ConclusionsHigh-dose fish oil does not reduce AF recurrence in patients with a history of AF not receiving conventional AA therapy. Furthermore, fish oil does not reduce inflammation or oxidative stress markers in this population, which may explain its lack of efficacy. (Multi-center Study to Evaluate the Effect of N-3 Fatty Acids [OMEGA-3] on Arrhythmia Recurrence in Atrial Fibrillation [AFFORD]; NCT01235130)

Sudden Cardiac Death Prediction in Arrhythmogenic Right Ventricular Cardiomyopathy: A Multinational Collaboration.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with ventricular arrhythmias (VA) and sudden cardiac death (SCD). A model was recently developed to predict incident sustained VA in patients with ARVC. However, since this outcome may overestimate the risk for SCD, we aimed to specifically predict life-threatening VA (LTVA) as a closer surrogate for SCD. METHODS: We assembled a retrospective cohort of definite ARVC cases from 15 centers in North America and Europe. Association of 8 prespecified clinical predictors with LTVA (SCD, aborted SCD, sustained, or implantable cardioverter-defibrillator treated ventricular tachycardia >250 beats per minute) in follow-up was assessed by Cox regression with backward selection. Candidate variables included age, sex, prior sustained VA (≥30s, hemodynamically unstable, or implantable cardioverter-defibrillator treated ventricular tachycardia; or aborted SCD), syncope, 24-hour premature ventricular complexes count, the number of anterior and inferior leads with T-wave inversion, left and right ventricular ejection fraction. The resulting model was internally validated using bootstrapping. RESULTS: A total of 864 patients with definite ARVC (40±16 years; 53% male) were included. Over 5.75 years (interquartile range, 2.77-10.58) of follow-up, 93 (10.8%) patients experienced LTVA including 15 with SCD/aborted SCD (1.7%). Of the 8 prespecified clinical predictors, only 4 (younger age, male sex, premature ventricular complex count, and number of leads with T-wave inversion) were associated with LTVA. Notably, prior sustained VA did not predict subsequent LTVA (P=0.850). A model including only these 4 predictors had an optimism-corrected C-index of 0.74 (95% CI, 0.69-0.80) and calibration slope of 0.95 (95% CI, 0.94-0.98) indicating minimal over-optimism. CONCLUSIONS: LTVA events in patients with ARVC can be predicted by a novel simple prediction model using only 4 clinical predictors. Prior sustained VA and the extent of functional heart disease are not associated with subsequent LTVA events

A new prediction model for ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy

Aims Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is characterized by ventricular arrhythmias (VAs) and sudden cardiac death (SCD). We aimed to develop a model for individualized prediction of incident VA/SCD in ARVC patients. Methods and results Five hundred and twenty-eight patients with a definite diagnosis and no history of sustained VAs/SCD at baseline, aged 38.2 ± 15.5 years, 44.7% male, were enrolled from five registries in North America and Europe. Over 4.83 (interquartile range 2.44–9.33) years of follow-up, 146 (27.7%) experienced sustained VA, defined as SCD, aborted SCD, sustained ventricular tachycardia, or appropriate implantable cardioverter-defibrillator (ICD) therapy. A prediction model estimating annual VA risk was developed using Cox regression with internal validation. Eight potential predictors were pre-specified: age, sex, cardiac syncope in the prior 6 months, non-sustained ventricular tachycardia, number of premature ventricular complexes in 24 h, number of leads with T-wave inversion, and right and left ventricular ejection fractions (LVEFs). All except LVEF were retained in the final model. The model accurately distinguished patients with and without events, with an optimism-corrected C-index of 0.77 [95% confidence interval (CI) 0.73–0.81] and minimal over-optimism [calibration slope of 0.93 (95% CI 0.92–0.95)]. By decision curve analysis, the clinical benefit of the model was superior to a current consensus-based ICD placement algorithm with a 20.6% reduction of ICD placements with the same proportion of protected patients (P < 0.001). Conclusion Using the largest cohort of patients with ARVC and no prior VA, a prediction model using readily available clinical parameters was devised to estimate VA risk and guide decisions regarding primary prevention ICD

Rationale and current perspective for early rhythm control therapy in atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and an important source for mortality and morbidity on a population level. Despite the clear association between AF and death, stroke, and other cardiovascular events, there is no evidence that rhythm control treatment improves outcome in AF patients. The poor outcome of rhythm control relates to the severity of the atrial substrate for AF not only due to the underlying atrial remodelling process but also due to the poor efficacy and adverse events of the currently available ion-channel antiarrhythmic drugs and ablation techniques. Data suggest, however, an association between sinus rhythm maintenance and improved survival. Hypothetically, sinus rhythm may also lead to a lower risk of stroke and heart failure. The presence of AF, thus, seems one of the modifiable factors associated with death and cardiovascular morbidity in AF patients. Patients with a short history of AF and the underlying heart disease have not been studied before. It is fair to assume that abolishment of AF in these patients is more successful and possibly also safer, which could translate into a prognostic benefit of early rhythm control therapy. Several trials are now investigating whether aggressive early rhythm control therapy can reduce cardiovascular morbidity and mortality and increase maintenance of sinus rhythm. In the present paper we describe the background of these studies and provide some information on their design

A new prediction model for ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy

Aims Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is characterized by ventricular arrhythmias (VAs) and sudden cardiac death (SCD). We aimed to develop a model for individualized prediction of incident VA/SCD in ARVC patients.Methods and results Five hundred and twenty-eight patients with a definite diagnosis and no history of sustained VAs/SCD at baseline, aged 38.2 +/- 15.5 years, 44.7% male, were enrolled from five registries in North America and Europe. Over 4.83 (interquartile range 2.44-9.33) years of follow-up, 146 (27.7%) experienced sustained VA, defined as SCD, aborted SCD, sustained ventricular tachycardia, or appropriate implantable cardioverter-defibrillator (ICD) therapy. A prediction model estimating annual VA risk was developed using Cox regression with internal validation. Eight potential predictors were pre-specified: age, sex, cardiac syncope in the prior 6 months, non-sustained ventricular tachycardia, number of premature ventricular complexes in 24 h, number of leads with T-wave inversion, and right and left ventricular ejection fractions (LVEFs). All except LVEF were retained in the final model. The model accurately distinguished patients with and without events, with an optimism-corrected C-index of 0.77 [95% confidence interval (CI) 0.73-0.81] and minimal over-optimism [calibration slope of 0.93 (95% CI 0.92-0.95)]. By decision curve analysis, the clinical benefit of the model was superior to a current consensus-based ICD placement algorithm with a 20.6% reduction of ICD placements with the same proportion of protected patients (P &lt;0.001).Conclusion Using the largest cohort of patients with ARVC and no prior VA, a prediction model using readily available clinical parameters was devised to estimate VA risk and guide decisions regarding primary prevention ICDs (www.arvcrisk.com).</p