From the Guidelines
Yes, hypertrophic obstructive cardiomyopathy (HOCM) can cause syncope, which is a temporary loss of consciousness. Syncope in HOCM can occur due to several mechanisms, including obstruction of blood flow from the left ventricle to the aorta during exertion or when standing quickly, reducing cardiac output and blood pressure, and leading to inadequate blood flow to the brain 1. Additionally, HOCM can trigger abnormal heart rhythms (arrhythmias) that may also cause syncope, as well as other causes such as hypovolaemia, complete heart block, sinus node dysfunction, sustained ventricular tachycardia, LVOTO, and abnormal vascular reflexes 1. Some key points to consider in the management of syncope in HOCM patients include:
- The use of beta-blockers like metoprolol (25-100 mg twice daily) or calcium channel blockers such as verapamil (120-360 mg daily in divided doses) to reduce heart contractility and outflow obstruction 1
- In severe cases, surgical myectomy or alcohol septal ablation may be necessary to reduce the obstruction 1
- Patients should avoid dehydration, excessive alcohol, and intense physical activity, particularly competitive sports, as these can trigger syncope episodes in HOCM patients
- Syncope during exertion, or immediately following palpitation or chest pain, suggests a cardiac mechanism, while syncope after prolonged standing in a hot environment, or during the postprandial absorptive state, is suggestive of neurally mediated (reflex) syncope 1. It is essential for patients with HOCM who experience syncope to seek immediate medical attention, as it can be a warning sign of increased risk for sudden cardiac death. Management should be guided by the most recent and highest quality evidence, with consideration of individual patient factors and clinical presentation 1.
From the Research
HOCM and Syncope
- Hypertrophic obstructive cardiomyopathy (HOCM) is a condition that can cause syncope, as reported in several studies 2, 3, 4.
- Syncope is a common symptom in patients with HOCM, with a reported incidence of 15.8% in one study 2.
- The etiology of syncope in HOCM is complex and can be due to various factors, including dynamic outflow tract obstruction, arrhythmic events, and hemodynamic changes 3.
Diagnosis and Management
- The diagnosis of syncope in HOCM requires a detailed history and physical examination, as well as diagnostic tests such as electrocardiography and echocardiography 3.
- Management of syncope in HOCM involves medical therapy, such as beta-blockers and calcium channel blockers, as well as invasive treatments like septal ablation and surgical myectomy 5, 6, 4.
- Patient selection for invasive treatment is crucial, and the choice of treatment depends on various factors, including the severity of symptoms, the presence of outflow tract obstruction, and the patient's overall health status 6.
Risk of Sudden Cardiac Death
- Syncope is a risk factor for sudden cardiac death in patients with HOCM, with a reported relative risk of 1.99 in one study 2.
- Patients with HOCM who experience syncope should be evaluated for the risk of sudden cardiac death and considered for implantable cardioverter-defibrillator (ICD) therapy 5, 3.