What are the characteristics and management of apical aneurysm in apical hypertrophic cardiomyopathy (HCM) without acute myocardial infarction (AMI)?

Characteristics and Management of Apical Aneurysm in Apical Hypertrophic Cardiomyopathy Without AMI

Apical aneurysms in apical hypertrophic cardiomyopathy (HCM) represent a high-risk phenotype associated with increased risk of sudden cardiac death, thromboembolism, and heart failure progression, requiring aggressive management with anticoagulation and consideration for ICD placement, particularly when aneurysm size is ≥2 cm.

Diagnostic Features of Apical Aneurysms in HCM

Morphological Characteristics

• Apical aneurysms are discrete thin-walled dyskinetic or akinetic segments at the left ventricular apex 1
• Prevalence is approximately 2% of all HCM patients 2
• Mean aneurysm size is approximately 1.77 ± 1.04 cm in large cohort studies 3
• Typically presents with an "hourglass-shaped" (71%) or distally hypertrophic (29%) left ventricle 4
• Often associated with mid-ventricular obstruction in approximately 10% of HCM patients 2

Imaging Findings

• Conventional echocardiography may miss apical aneurysms in about 10% of cases due to limited apical visualization 2
• Cardiovascular Magnetic Resonance (CMR) is the gold standard for detection due to superior spatial resolution 2, 1
• CMR can detect late gadolinium enhancement (LGE) indicating myocardial fibrosis/scarring in the aneurysm border 2, 1
• Contrast-enhanced echocardiography may improve detection when CMR is unavailable 1

Pathophysiological Mechanisms

• Development likely related to increased wall stress and microvascular ischemia despite normal epicardial coronary arteries 5
• Mid-ventricular obstruction often precedes aneurysm formation, creating high apical pressures 2
• Extensive myocardial scarring typically surrounds the aneurysm, creating substrate for arrhythmias 2

Clinical Significance and Risks

Arrhythmic Risk

• Apical aneurysms are associated with increased risk of sudden cardiac death (SCD) with an annualized event rate of 1.77% per year 3
• Ventricular tachycardia (VT) is common, with sustained VT reported in 38% of patients 4
• Risk of SCD increases with aneurysm size (HR 1.69 per 1-cm increase) 3
• Aneurysm size ≥2 cm is associated with a 5-year SCD rate of 9.7% compared to 2.9% for smaller aneurysms 3

Thromboembolic Risk

• High risk of thrombus formation within the aneurysm (46% of patients) 4
• Annualized rate of stroke or thrombus formation is 2.9% per year 3
• Risk increases with aneurysm size (HR 1.60 per 1-cm increase) 3
• Aneurysm size ≥2 cm has a significantly higher risk of stroke/thrombus (HR 2.20) 3

Heart Failure Risk

• Associated with progressive heart failure with an annualized rate of 1.28% per year for developing LV systolic dysfunction (EF <50%) 3
• Risk of developing LV dysfunction increases with aneurysm size (HR 1.63 per 1-cm increase) 3
• Overall adverse event rate (combined SCD, stroke, or LV dysfunction) is 2.12% per year 3

Management Approach

Risk Stratification

• CMR imaging is essential to accurately measure aneurysm size and extent of LGE 2
• Periodic reassessment with CMR every 3-5 years is recommended to evaluate changes in aneurysm size and LGE 2
• 24-48 hour ambulatory ECG monitoring is recommended in the initial evaluation and every 1-2 years for arrhythmia detection 2

Arrhythmia Management

• ICD implantation should be strongly considered for primary prevention in patients with aneurysm size ≥2 cm 3
• For patients with monomorphic ventricular tachycardia related to apical scarring, catheter ablation may be considered 2
• Antiarrhythmic therapy with beta-blockers and/or amiodarone is typically used 6

Thromboembolic Prevention

• Long-term oral anticoagulation is recommended for patients with documented thrombi 2, 3
• Prophylactic anticoagulation should be considered for patients with aneurysm size ≥2 cm due to higher thromboembolic risk 3, 7
• Regular monitoring for thrombus formation with imaging is essential 3

Heart Failure Management

• Standard heart failure therapy for patients with reduced ejection fraction 2
• High-dose beta-blockers, verapamil, or diltiazem for mid-ventricular obstruction, though response is often suboptimal 2
• In selected cases with severe symptoms and mid-ventricular obstruction, surgical approaches may be considered 2

Surgical Considerations

• Aneurysmectomy may be beneficial in selected high-risk patients 4
• Surgical approaches for mid-ventricular obstruction include transaortic myectomy, transapical approach, or combined approaches 2
• Surgical outcomes appear favorable with no adverse events reported in small series of patients undergoing aneurysmectomy 4

Clinical Pitfalls to Avoid

• Relying solely on echocardiography for diagnosis, which may miss up to 10% of apical aneurysms 1
• Failing to distinguish between true apical aneurysm and the normal "ace of spades" configuration of apical HCM 1
• Underestimating thromboembolic risk, particularly in patients with larger aneurysms 3, 7
• Neglecting periodic reassessment with CMR to detect progression of aneurysm size or LGE 2
• Missing the diagnosis of apical aneurysm in patients with unexplained stroke or systemic embolism 7