This international consensus statement is intended to help cardiologists and other health care professionals involved in the care of adult and pediatric patients with arrhythmogenic cardiomyopathy (ACM), which encompasses a broad range of disorders, by providing recommendations for evaluation and management and supporting shared decision making between health care providers and patients in a document format that is also useful at the point of care.This consensus statement was written by experts in the field chosen by the Heart Rhythm Society (HRS) and collaborating organizations.

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Sinus node dysfunction (SND) and atrial arrhythmias frequently coexist and interact to initiate and perpetuate each other. Atrial arrhythmias are present in 40% to 70% of patients at the time of diagnosis of SND.1,2 However, the complex relationship between the 2 remains ill defined. The documented degenerative changes in atrial myocardial structure relating to SND are primarily right atrial. Yet, the majority of triggers and substrates for atrial fibrillation (AF) originate from the left atrium. Although progressive biatrial fibrosis is a feature in patients with structural heart disease and in senescence, paroxysmal AF that occurs in patients with no structural heart disease may have a different pathophysiology. SND associated with this latter condition is likely to be primarily a result of electric remodeling and potentially reversible. The time course of the progression of SND and AF 3 and their individual clinical manifestations also vary depending on the underlying pathology. The purpose of this review is to summarize the state of our knowledge of sinus node (SN) function in both health and disease, and to understand the complex relationship between SN disease and atrial arrhythmias. Structure and Functional Components of the Sinus NodeIn the adult human heart, the SN is a crescent-shaped structure 1 to 2 cm long and 0.5 cm wide that lies at the junction of the superior vena cava with the right atrium and lies along the sulcus terminalis. The node itself is composed of clusters of pacemaker myocytes arranged in parallel rows with short digitations that frequently anastomose with the surrounding atrial tissue. The specialized pacemaker cells are interspersed with nerves and capillaries and scaffolded by dense connective tissue to form the SN pacemaker complex. The caudal portion fragments to merge with the atrial myocardium. The lack of a distinct encapsulation and the radiating sinoatrial connections explains the lack of a single breakthrough of the sinus impulse. The position of the leading pacemaker site shifts within the node and varies with sympathetic and vagal stimulation. 3The SN pacemaker cells are interspersed with interstitial collagen that varies in extent as a function of older age. 4 Collagen content increases from 24% in the infant to 70% in the adult heart.5 The fibrous matrix with surrounding fatty insulation of the SN together with distinct electrophysiological properties (see below) provides insulation and prevents the depression of pacemaker automaticity from the hyperpolarizing electric load of the surrounding atrial myocardium. 6 Multiple currents are involved in the activation of the SN. The predominant inward current in the center of the node is I CaL . Action potentials with slow upstrokes initiated in the center spreads peripherally and into the musculature of the terminal crest. However, in the periphery of the node, I Na is operative and is necessary for providing sufficient inward current to depolarize the larger mass of atrial tissue. Delayed rectifier potassium currents facili...

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BackgroundSleep apnea (SA) is associated with an increased risk of atrial fibrillation (AF). We sought to determine the effect of SA on cardiac structure in patients with AF, whether therapy for SA was associated with beneficial cardiac structural remodelling, and whether beneficial cardiac structural remodelling translated into a reduced risk of recurrence of AF after pulmonary venous isolation (PVI).Methods and ResultsA consecutive group of 720 patients underwent a cardiac magnetic resonance study before PVI. Patients with SA (n=142, 20%) were more likely to be male, diabetic, and hypertensive and have an increased pulmonary artery pressure, right ventricular volume, atrial dimensions, and left ventricular mass. Treated SA was defined as duration of continuous positive airway pressure therapy of >4 hours per night. Treated SA patients (n=71, 50%) were more likely to have paroxysmal AF, a lower blood pressure, lower ventricular mass, and smaller left atrium. During a follow‐up of 42 months, AF recurred in 245 patients. The cumulative incidence of AF recurrence was 51% in patients with SA, 30% in patients without SA, 68% in patients with untreated SA, and 35% in patients with treated SA. In a multivariable model, the presence of SA (hazard ratio 2.79, CI 1.97 to 3.94, P<0.0001) and untreated SA (hazard ratio 1.61, CI 1.35 to 1.92, P<0.0001) were highly associated with AF recurrence.ConclusionsPatients with SA have an increased blood pressure, pulmonary artery pressure, right ventricular volume, left atrial size, and left ventricular mass. Therapy with continuous positive airway pressure is associated with lower blood pressure, atrial size, and ventricular mass, and a lower risk of AF recurrence after PVI.

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