'Epidemiology' above.) Risk factors Several factors predispose to the development of AF in patients with HCM, including increased left atrial diameter and volume, left atrial dysfunction, increasing age, and left ventricular ejection fraction (LVEF), particularly when LVEF <50 percent (end-stage HCM). In contrast to these risk factors, the presence or severity of an LV outflow tract (LVOT) gradient does not appear to be associated with an increased incidence of AF. (See 'Predisposing factors' above.) Clinical manifestations While most patients with HCM who develop AF have fairly prominent symptoms, not all patients will be symptomatic. The acute symptoms associated with AF in patients with HCM, which may include palpitations, dyspnea, and chest pain, are similar to the symptoms of AF in patients without HCM. However, patients with HCM, especially those with an LVOT gradient, are also at risk for hypotension, lightheadedness, presyncope, and syncope. (See 'Clinical manifestations' above.) https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 12/21 7/5/23, 9:14 AM Hypertrophic cardiomyopathy in adults: Supraventricular tachycardias including atrial fibrillation - UpToDate The long-term consequences of both paroxysmal and persistent/permanent AF in patients with HCM include an increase in limiting symptoms and risk of thromboembolic stroke, as well as decreased overall functional status. Unlike ventricular arrhythmias, however, AF is not clearly associated with an increased risk of sudden cardiac death. (See 'Clinical manifestations' above.) Diagnosis The diagnosis of AF is usually suspected in a patient with palpitations, dyspnea, or chest pain with an irregularly irregular pulse present on physical examination and confirmed by obtaining an ECG. (See 'Diagnosis' above.) Initial management In patients who are asymptomatic or have only mild to moderate symptoms, the initial management of AF is similar to other patients with AF and includes slowing the ventricular rate and concurrent initiation of anticoagulation therapy ( algorithm 1). (See 'Initial management' above and "Atrial fibrillation: Cardioversion" and "Cardioversion for specific arrhythmias".) In patients with severe symptoms or who are hemodynamically unstable related to AF, urgent cardioversion should be performed. Long-term management Rhythm versus rate control In symptomatic patients with HCM and paroxysmal or persistent AF, we suggest a rhythm control strategy (Grade 2C). This can be accomplished with either chemical or electrical cardioversion to restore sinus rhythm and antiarrhythmic drugs to suppress recurrences of AF. Although various professional society guidelines have concluded that the available data were insufficient to recommend one antiarrhythmic drug over another, our experts generally use sotalol (rather than amiodarone or disopyramide). In selected cases, catheter-based radiofrequency ablation or a surgical maze procedure may be appropriate. (See 'Rhythm control' above.) A rate control strategy is also reasonable. For patients in whom a rate control strategy is selected, we recommend the use of beta blockers, calcium channel blockers, or the two drugs in combination, rather than digoxin (Grade 1B). (See 'Rate control' above.) If rate control is not achieved with medications and catheter or surgical ablation is not an option, patients may undergo atrioventricular (AV) nodal ablation with placement of a permanent pacemaker for definitive rate control. (See 'Rate control' above.) Anticoagulation The CHA DS -VASc score has not been studied in patients with HCM 2 2 and therefore cannot be applied to patients with AF and HCM to determine need for https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 13/21 7/5/23, 9:14 AM Hypertrophic cardiomyopathy in adults: Supraventricular tachycardias including atrial fibrillation - UpToDate anticoagulation. For patients with HCM and clinical AF and subclinical AF >24 hours duration, we recommend chronic oral anticoagulation (Grade 1A). Either warfarin (with a target international normalized ratio [INR] of 2 to 3) or one of the direct oral anticoagulants (DOACs; eg, dabigatran, rivaroxaban, apixaban) can be chosen as the initial thrombotic regimen in patients with HCM and AF. For patients with shorter episodes of subclinical AF, anticoagulation therapy may be reasonable. 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Topic 4926 Version 38.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 17/21 7/5/23, 9:14 AM Hypertrophic cardiomyopathy in adults: Supraventricular tachycardias including atrial fibrillation - UpToDate GRAPHICS Morphologic variants of hypertrophic cardiomyopathy HCM typically presents with asymmetric or localized areas of LV hypertrophy, which are diagrammed in B to J. (A) Normal LV wall thickness. (B) ASH. (C) Sigmoid septum, which is more common in older adults. (D) Midcavity hypertrophy associated with midcavity obstruction. (E) Predominantly free wall hypertrophy, an unusual pattern in HCM. (F) LV wall thinning (associated with low LV ejection fraction) and biatrial enlargement. (G) Predominantly apical LV hypertrophy. (H) Severe concentric hypertrophy with cavity obliteration. (I) Biventricular hypertrophy. (J) Mild to moderate symmetric hypertrophy. https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 18/21 7/5/23, 9:14 AM Hypertrophic cardiomyopathy in adults: Supraventricular tachycardias including atrial fibrillation - UpToDate HCM: hypertrophic cardiomyopathy; LV: left ventricular; ASH: asymmetrical septal hypertrophy. Graphic 58156 Version 6.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 19/21 7/5/23, 9:14 AM Hypertrophic cardiomyopathy in adults: Supraventricular tachycardias including atrial fibrillation - UpToDate Management of atrial fibrillation in patients with hypertrophic cardiomyopathy Algorithmic approach to the management of AF in patients with HCM. The approach in this population is sim AF management, with consideration of all three major management questions (anticoagulation, rate control, patient. AF: atrial fibrillation; HCM: hypertrophic cardiomyopathy; BB: beta blocker; CCB: calcium channel blocker; INR CV: cardioversion; RFA: radiofrequency ablation. Patients with AF and rapid HR who are unstable should undergo urgent electrical cardioversion. Graphic 119349 Version 1.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 20/21 7/5/23, 9:14 AM Hypertrophic cardiomyopathy in adults: Supraventricular tachycardias including atrial fibrillation - UpToDate Contributor Disclosures Martin S Maron, MD Grant/Research/Clinical Trial Support: iRhythm [Hypertrophic cardiomyopathy]. Consultant/Advisory Boards: Cytokinetics [Steering committee, REDWOOD-HCM]; Edgewise Pharmaceuticals [Myosin inhibitor for treatment of symptomatic hypertrophic cardiomyopathy]; Imbria Pharmaceuticals [Hypertrophic cardiomyopathy]. All of the relevant financial relationships listed have been mitigated. Samuel L vy, MD No relevant financial relationship(s) with ineligible companies to disclose. William J McKenna, MD Consultant/Advisory Boards: Bristol Meyers Squibb [Novel pharmacological treatments for HCM]; Cytokinetics [Novel pharmacological treatments for HCM]; Health in Code [Genetic testing in inherited cardiac disease]; Tenaya Therapeutics [Gene therapy in cardiomyopathy]. All of the relevant financial relationships listed have been mitigated. Todd F Dardas, MD, MS No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-in-adults-supraventricular-tachycardias-including-atrial-fibrillation/print 21/21