Reducing radiation exposure during procedures performed in the electrophysiology laboratory.

INTRODUCTION: Expert societies recently published strong recommendations to reduce the exposure of patients and staff to ionizing radiation (IR) during interventional and electrophysiology (EP) procedures. However, adherence to these guidelines remains difficult and the impact of implementing such recommendations is poorly characterized. METHODS AND RESULTS: We conducted a single-center cohort study to quantify radiation exposure over time in three EP laboratories at the Montreal Heart Institute during 5,546 consecutive procedures from 2012 to 2015 by 11 primary operators. Overall, 2,618 (47.2%) procedures were catheter-based and 2,928 (52.8%) were device interventions. Interventions to reduce radiation exposure included educational initiatives to raise awareness (i.e., limiting cine acquisition, patient position, table height), slower frame rate, lower radiation dose per pulse, collimation, and integration with 3-D mapping systems and/or MediGuide technology. An 85% reduction in IR exposure was observed from 2012 to 2015, with the mean dose-area-product (DAP) decreasing from 7.65 ± 0.05 Gy·cm2 to 1.15 ± 0.04 Gy·cm2 (P < 0.001). This was true for catheter-based procedures (mean DAP 16.99 ± 0.08 to 2.00 ± 0.06 Gy·cm2 , P < 0.001) and device interventions (mean DAP 4.18 ± 0.06 to 0.64 ± 0.05 Gy·cm2 , P < 0.001). The median effective dose of IR recorded per quarter by 282 cervical dosimeters on EP staff decreased from 0.57 (IQR 0.18, 1.03) mSv in 2012 to 0.00 (IQR 0.00, 0.19) mSv in 2015, P < 0.001. CONCLUSION: Enforcing good clinical practices with simple measures and low-dose fluoroscopy settings are highly effective in reducing IR exposure in the EP lab. These promising results should encourage other EP labs to adopt similar protective measures.

Predictors of Ventricular Arrhythmias and Sudden Death in a Québec Cohort With Brugada Syndrome.

BACKGROUND: Patients with Brugada syndrome (BrS) are at risk for ventricular arrhythmias (VAs) and sudden death. Identification of high-risk individuals beyond those with syncope or resuscitated sudden death remains a major challenge. METHODS: We assessed the value of clinical, electrophysiological, and electrocardiographic (ECG) features, including depolarization and repolarization metrics, in predicting arrhythmic events and sudden death in consecutive patients with BrS diagnosed between 2002 and 2013 in Quebec, Canada. Qualifying electrocardiograms with the highest type 1 ST-segment elevations were reviewed and analyzed by 2 electrophysiologists who were blinded to clinical history. Survival analyses were adjusted for Firth bias correction and left truncation. RESULTS: A total of 105 patients, 79.8% of whom were men, were diagnosed with BrS at a mean age of 46.2 ± 13.3 years and were followed for 59.6 ± 16.4 months. Ten (9.5%) had a history of cardiac arrest, 37 (35.2%) had syncope, and 7 (6.7%) experienced 20 arrhythmic events during follow-up, all consisting of appropriate ICD therapy (7 antitachycardia pacing; 13 shocks). In multivariate Cox regression analyses, a spontaneous type 1 electrocardiographic (ECG) pattern (hazard ratio [HR], 10.80; 95% confidence interval [CI], 1.03-113.87; P = 0.0476), maximal T peak-end (Tp-e) duration ≥ 100 ms (HR, 29.73; 95% CI, 1.33-666.37; P = 0.0325), and QRS duration in lead V6 > 110 ms (HR, 15.27; 95% CI, 1.07-217.42; P = 0.0443) were independently associated with VAs or aborted sudden cardiac death. CONCLUSIONS: In a multicentre cohort with BrS from Quebec, Canada, VAs and sudden death were independently associated with standard 12-lead ECG features, including a spontaneous type 1 pattern, depolarization (QRS in lead V6), and repolarization (maximal Tp-e duration) criteria.

New directions in cardiac arrhythmia management: present challenges and future solutions.

Cardiac arrhythmias are a major contributor to population morbidity and mortality. Enormous advances in arrhythmia management have occurred over the 60 years since the founding of the Montreal Heart Institute, but important challenges remain. The purpose of this article is to identify the areas of cardiac arrhythmia therapy that need improvement and to discuss the evolving approaches that promise solutions. Challenges in diagnosis, detection, and risk-stratification include difficulties in separating benign from high-risk syncope and pinpointing the underlying causes, the detection of silent atrial fibrillation in patients at risk of stroke, and inadequate identification of sudden-death risk. Implantable devices are limited by the need for battery and device replacements, device complications like infection and dysfunction, and lead complications like fracture, infection, or displacement. Antiarrhythmic drug therapy, although widely used, is plagued by a very limited range of available agents, supply issues, insufficient efficacy, and significant adverse effect risk. Health economic concerns include the high cost of new technologies, challenges in establishing cost effectiveness, and restrictive practices of government or third-party payers. Major improvements in arrhythmia management can be expected from new discoveries and technological developments in genetics, innovative diagnostic tools for arrhythmia monitoring, imaging and analysis, new approaches to antiarrhythmic drug development, biological therapies, and continuing improvement in implantable device technology like further miniaturization, leadless technology, and use of novel energy sources. As exciting as the developments in arrhythmia management have been in the past, we can look forward to exponential improvement in our ability to manage arrhythmia patients in the near future.

Clinical experience with a novel electromyographic approach to preventing phrenic nerve injury during cryoballoon ablation in atrial fibrillation.

BACKGROUND: Phrenic nerve palsy remains the most frequent complication associated with cryoballoon-based pulmonary vein (PV) isolation. We sought to characterize our experience using a novel monitoring technique for the prevention of phrenic nerve palsy. METHODS AND RESULTS: Two hundred consecutive cryoballoon-based PV isolation procedures between October 2010 and October 2013 were studied. In addition to standard abdominal palpation during right phrenic nerve pacing from the superior vena cava, all patients underwent diaphragmatic electromyographic monitoring using surface electrodes. Cryoablation was terminated on any perceived reduction in diaphragmatic motion or a 30% decrease in the compound motor action potential (CMAP). During right-sided ablation, a ≥30% reduction in CMAP amplitude occurred in 49 patients (24.5%). Diaphragmatic motion decreased in 30 of 49 patients and was preceded by a 30% reduction in CMAP amplitude in all. In 82% of cases, this reduction in CMAP amplitude occurred during right superior PV isolation. The baseline CMAP amplitude was 946.5±609.2 mV and decreased by 13.8±13.8% at the end of application. This decrease was more marked in the 33 PVs with a reduction in diaphragmatic motion than in those without (40.9±15.3% versus 11.3±10.5%; P<0.001). In 3 cases, phrenic nerve palsy persisted beyond the end of the procedure, with all cases recovering within 6 months. Despite the shortened application all veins were isolated. At repeat procedure the right-sided PVs reconnected less frequently than the left-sided PVs in those with phrenic nerve palsy. CONCLUSIONS: Electromyographic phrenic nerve monitoring using the surface CMAP is reliable, easy to perform, and offers an early warning to impending phrenic nerve injury.

Diagnostic tools for arrhythmia detection in adults with congenital heart disease and heart failure.

As patients with congenital heart disease age with increasingly complex lesions, heart failure and arrhythmias have emerged as leading sources of morbidity and mortality. The two are intertwined, as one may herald, beget, or aggravate the other. Moreover, arrhythmias in adults with congenital heart disease and heart failure can be poorly tolerated or life threatening. There is, therefore, much interest in promptly and accurately diagnosing arrhythmias and identifying risk factors for sudden death. This article appraises current knowledge regarding diagnostic tools for arrhythmias in adults with congenital heart disease and heart failure and comments on their prognostic value where relevant.