Approach to Exertional Syncope Due to HOCM

Initial Diagnostic Workup

The European Society of Cardiology recommends a 12-lead ECG to identify conduction abnormalities, bradyarrhythmias, or signs of ventricular hypertrophy in patients with exertional syncope and HOCM 1, 2
The American College of Cardiology suggests a standard upright exercise test to reproduce symptoms, assess blood pressure response, and evaluate for exercise-induced arrhythmias in patients with exertional syncope and HOCM 1, 3
The European Heart Journal recommends 48-hour ambulatory ECG monitoring to detect paroxysmal arrhythmias including atrial fibrillation with rapid ventricular response, ventricular tachycardia, or bradyarrhythmias in patients with exertional syncope and HOCM 1, 2
Exercise echocardiography is critical in patients with exertional or postural syncope to detect provocable LVOTO, as recommended by the American College of Cardiology and the European Society of Cardiology 1, 2, 3

The American Heart Association and the American College of Cardiology emphasize that exertional syncope in HOCM has multiple potential causes, including LVOTO, ventricular arrhythmias, atrial arrhythmias with fast ventricular response, abnormal blood pressure response, and bradyarrhythmias 1, 2, 3, 5
The European Society of Cardiology notes that syncope during exertion or immediately following palpitation or chest pain strongly suggests a cardiac mechanism rather than neurally-mediated syncope 1, 2

The European Society of Cardiology states that unexplained non-vasovagal syncope is a major risk factor for sudden cardiac death, particularly in young patients occurring in close temporal proximity to their first evaluation 1, 2
The American College of Cardiology recommends assessing additional high-risk features, including age <40 years with abnormal exercise blood pressure response, family history of sudden cardiac death, massive left ventricular hypertrophy, and non-sustained ventricular tachycardia on ambulatory monitoring 3, 4

The American College of Cardiology recommends non-vasodilating beta-blockers as first-line pharmacotherapy for symptomatic HOCM with LVOTO, with a target heart rate <60-65 bpm 7
The European Heart Journal suggests non-dihydropyridine calcium channel blockers, such as verapamil or diltiazem, if beta-blockers fail or are not tolerated 7

The European Society of Cardiology recommends considering implantable loop recorder (ILR) for recurrent episodes of unexplained syncope in patients at low risk of sudden cardiac death 1, 2
Electrophysiological studies are indicated only if there is evidence from non-invasive tests suggesting sino-atrial disease, AV block, or persistent supraventricular tachycardia, as recommended by the European Society of Cardiology 1

The American College of Cardiology recommends treating bradyarrhythmia according to current cardiac pacing guidelines, with permanent pacemaker may be required for symptomatic bradycardia or high-degree AV block 1, 2
The European Heart Journal suggests anticoagulation with vitamin K antagonist (INR 2-3) for atrial fibrillation, even for short episodes, due to high thromboembolic risk 7

The European Society of Cardiology recommends hospital admission for syncope occurring during exercise, suspected or known significant heart disease with syncope, ECG abnormalities suspected of arrhythmic syncope, and patients requiring continuous monitoring, urgent echocardiography, and risk stratification 8