Background— Genotyping in hypertrophic cardiomyopathy has gained increasing attention in the past decade. Its major role is for family screening and rarely influences decision-making processes in any individual patient. It is associated with substantial costs, and cost-effectiveness can only be achieved in the presence of high-detection rates for disease-causing sarcomere protein gene mutations. Therefore, our aim was to develop a score based on clinical and echocardiographic variables that allows prediction of the probability of a positive genotype. Methods and Results— Clinical and echocardiographic variables were collected in 471 consecutive patients undergoing genetic testing at a tertiary referral center between July 2005 and November 2010. Logistic regression for a positive genotype was used to construct integer risk weights for each independent predictor variable. These were summed for each patient to create the Toronto hypertrophic cardiomyopathy genotype score. A positive genotype was found in 163 of 471 patients (35%). Independent predictors with associated-risk weights in parentheses were as follows: age at diagnosis 20 to 29 (−1), 30 to 39 (−2), 40 to 49 (−3), 50 to 59 (−4), 60 to 69 (−5), 70 to 79 (−6), ≥80 (−7); female sex (4); arterial hypertension (−4); positive family history for hypertrophic cardiomyopathy (6); morphology category (5); ratio of maximal wall thickness:posterior wall thickness <1.46 (0), 1.47 to 1.70 (1), 1.71 to 1.92 (2), 1.93 to 2.26 (3), ≥2.27 (4). The model had a receiver operator curve of 0.80 and Hosmer–Lemeshow goodness-of-fit P =0.22. Conclusions— The Toronto genotype score is an accurate tool to predict a positive genotype in a hypertrophic cardiomyopathy cohort at a tertiary referral center.

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Obstructive sleep apnea (OSA) is a highly prevalent disorder with a growing incidence worldwide that closely mirrors the global obesity epidemic. OSA is associated with enormous healthcare costs in addition to significant morbidity and mortality. Much of the morbidity and mortality related to OSA can be attributed to an increased burden of cardiovascular disease, including cardiac rhythm disorders. Awareness of the relationship between OSA and rhythm disorders is variable among physicians, a fact that can influence patient care, since the presence of OSA can influence the incidence, prevalence, and successful treatment of multiple rhythm disorders. Herein, we provide a review of this topic that is intentionally broad in scope, covering the relationship between OSA and rhythm disorders from epidemiology and pathophysiology to diagnosis and management, with a particular focus on the recognition of undiagnosed OSA in the general clinical population and the intimate relationship between OSA and atrial fibrillation.

Introduction Ablation of atrial vagal ganglia has been associated with improved pulmonary vein isolation (PVI) outcomes. Disruption of vagal reflexes results in heart rate (HR) increase. We investigated the association between HR change after PVI and freedom from atrial fibrillation (AF) at 1 year. Methods and Results Patients who underwent PVI for paroxysmal AF were identified from the Johns Hopkins Hospital AF registry. Electrocardiograms taken pre‐PVI and post‐PVI were used to determine the change in HR. Patients followed‐up at 3, 6, and 12 months. Of 257 patients (66% male, age 59+/‐11 years), 134 (52%) remained free from AF at 1 year. The average HR increased from 60.6 ± 11.3 beats per minute (bpm) pre‐PVI to 70.7 ± 12.0 bpm post‐PVI. Patients with recurrence of AF had lower post‐PVI HR than those who remained free from AF (67.8 ± 0.2 vs 73.3 ± 13.0 bpm; P <.001). The probability of AF recurrence at 1‐year decreased as the change in HR increased (estimated odds ratio [OR], 0.83; 95% confidence interval [CI, 0.74‐0.93]; P = .002). HR increase more than 15 bpm was associated with the lowest odds of AF recurrence (estimated OR, 0.39; 95% [0.17‐0.85]; P = .018) compared to HR decrease. Conclusions Resting HR was found to increase after PVI. Increase in HR more than 15 bpm has a positive association with remaining free from atrial fibrillation at 1 year.

Introduction: Leadless cardiac pacemakers are an alternative modality to traditional transvenous pacemaker systems. Recently receiving Food and Drug Administration approval, the AVEIR VR leadless pacemaker system provides a helix based active fixation leadless pacemaker system. This step-by-step review will cover patient selection, preprocedural planning, device implantation technique, implant site evaluation, troubleshooting, short-and long-term complications as well as future directions for leadless pacing.Methods: We collected and reviewed cases from primary operators to provide a step-by-step review for implanters. Results:Our paper provides a guide to patient selection, pre-procedural planning, device im plantation technique, implant site evaluation, troubleshooting, short-and long-term complications as well as future directions for leadless pacing. Conclusion:The helix based active fixation leadless pacemaker system is a safe and efficacious way to provide pacing support to patients and provides an alternative to transvenous pacing systems. Our review provides a step-by-step guide to implantation.

Background: Transthyretin (TTR) cardiac amyloidosis (CA) results from TTR protein deposition in the extracellular space of the heart altering cardiac chamber mechanics and efficiency. Ventriculo-arterial coupling (VAC) is calculated from 2D echo derived measurements and reflects cardiac function and efficiency. We aimed to identify whether VAC assessment at diagnosis improves current risk stratification models as a prognostic tool. Methods: The Amyloid Heart Disease registry at our institution was used to identify 365 TTR-CA patients. Primary outcome was mortality and advanced heart failure therapy (ventricular assist device (VAD) or heart transplant). Results: At a median follow up of 1.9 years, VAD, transplant or death occurred in 163 (44.7%) patients. On adjusted multivariable Cox survival analysis, the Gillmore Stage which incorporates eGFR and NTproBNP (HR=2.5, 95% CI 1.96-3.18), CAD (HR=1.50 95% CI 1.02-2.20), therapy with Tafamidis (HR=0.31, 95% CI 0.19-0.51), and VAC greater than median (>1.01) (HR=2.28 95% CI 1.57-3.29, p<0.001) were independently associated with outcome (all p<0.05) (Figure). Conclusion: The easily measurable and widely available echo parameter VAC provides incremental independent value in patients with TTR-CA.

Introduction: Flecainide is a class 1c antiarrhythmic commonly used for the treatment of atrial and ventricular arrhythmias in the absence of underlying structural heart disease. The significant proarrhythmic effects of the drug warrant familiarity with the drug and its toxicity. Flecainide overdose, whether intentional or iatrogenic, is a life threatening emergency with mortality rates as high as 22.5%. We present a case of intentional flecainide overdose and its management. Case: A 78-year-old man with a history of heart failure, paroxysmal atrial fibrillation on flecainide, presented to a local ED after a suicide attempt. He was initially hemodynamically stable and a 12-lead EKG revealed a wide-QRS bradyarrhythmia (See figure 1). Electrolyte panel showed normal potassium and pH. During transport to our tertiary cardiac intensive care unit, the patient declined and was critically ill on arrival. The diagnosis of flecainide toxicity was suspected and therapy was initiated on arrival. Despite therapy with sodium bicarbonate and fat emulsion, the patient continued to decline. Renal replacement therapy was started and the patient was evaluated for mechanical circulatory support. Ultimately, the patient’s family elected for palliative extubation. The patient’s flecainide level returned more than four times above the therapeutic range. Discussion: This case highlights the importance of a high index of suspicion when faced with a wide-QRS arrythmia in a patient with suspected antiarrhythmic overdose. The persistence of these rhythms after correction of acid-base abnormalities and electrolyte derangements should prompt aggressive, empiric treatment of potential overdose. The presence of electromechanical dyssynchrony in this context is an ominous sign and should prompt simultaneous evaluation for biventricular mechanical circulatory support concomitant with medical therapy for suspected overdose. Figure 1

Cardiac electrophysiology procedures have evolved to provide improvement in morbidity and mortality for many patients. Cardiac resynchronization therapy (CRT), implantable cardioverter/defibrillator (ICD) placement and lead extraction procedures are proven procedures, associated with significant reductions in patient morbidity and mortality as well as improved quality of life. The applications and optimization of these therapies are an evolving field. The optimal use and outcomes of cardiac electrophysiology procedures require a multidisciplinary approach to patient selection, device selection, and procedural planning. Cardiac imaging using echocardiography plays a key role in selection of patients for CRT therapy, for guidance of left ventricular (LV) lead placement, and for optimization of atrioventricular pacing delays in patients with CRT. Cardiac computed tomography (CT) is an important tool in assessment of lead perforation, as well as assessing risk of lead extraction and procedural planning. Cardiac magnetic resonance imaging (MRI) is an important adjunct to transthoracic echocardiography for patient selection and risk stratification for defibrillator therapy for multiple disease states including ischemic cardiomyopathy, hypertrophic cardiomyopathy, cardiac sarcoidosis, and arrhythmogenic right ventricular cardiomyopathy (ARVC). Cardiac positron emission tomography (PET) is a useful adjunct to the diagnosis of device infections as well as inflammatory conditions including cardiac sarcoidosis. Our review attempts to summarize the contemporary roles of multimodality imaging in CRT therapy, ICD therapy and lead extraction therapy.