Submitral Diverticulum in Hypertrophic Cardiomyopathy in an Adult Male: A Phenotypic Marker for Electrophysiological Consequences

Abstract

Submitral diverticulum of left ventricle is rare entity often presumed to be congenital in origin having preserved myocardial contractility and function. Patients may be entirely asymptomatic for many years or may have varied clinical or electrophysiological manifestations. We present a case of a middle-aged man with hypertrophic cardiomyopathy who presented with atrial fibrillation and ventricular tachycardia detected to have submitral diverticulum on computed tomography angiography which further assisted in planning of electrophysiology ablation.

Keywords

arrythmia - CT angiography - electrophysiology - hypertrophic cardiomyopathy

Introduction

A gentleman in his fifties presented with palpitations and exertional dyspnea for 1 year. On examination, the patient's pulse was irregular. He had a sustained apical impulse, and a fourth heart sound was appreciated. The 12-lead electrocardiogram showed atrial fibrillation (AF) with fast ventricular rate. Transthoracic echocardiography revealed hypertrophic cardiomyopathy (HCM) with severe left ventricular hypertrophy ([Fig. 1A], [Supplementary Video S1]). There was no mitral regurgitation and no systolic anterior motion of the anterior mitral leaflet ([Fig. 1B]). No dynamic left ventricular outflow tract obstruction was noted. A deep submitral myocardial diverticulum (SMD) was identified in the basal inferior segment in a two-chamber view ([Fig. 1C], white arrow). The diverticulum demonstrated diastolic prominence with partial systolic obliteration. He was planned for ablation for AF and cardiac computed tomography angiography (CTCA) was done for pulmonary venous anatomy. The CTCA also confirmed a deep SMD (4 × 5 cm) in basal inferior segment ([Fig. 1D, E], white arrow; [Supplementary Video S2]). Volumetric reconstruction also highlighted the morphological aspects of SMD ([Fig. 1E], white arrow). He underwent successful ablation for AF with symptomatic relief.

Fig. 1 Transthoracic echocardiography (TTE) image (A) in parasternal long axis view showing severe left ventricular hypertrophy. M mode echocardiography image (B) showing severe left ventricular hypertrophy. No evidence of systolic anterior motion of anterior mitral leaflet is noted. TTE image in two-chamber view showing submitral diverticulum in inferior wall of left ventricle (white arrow in C). Multiplanar reconstructed computed tomography images in vertical longitudinal axis (D) and short axis (E) views demonstrating submitral diverticulum (white arrow) in basal inferior segment of left ventricle. Three-dimensional reconstructed virtual dissection image (F) showing submitral diverticulum (white arrow).

Download Video

Supplementary Video S1 Two-chamber echocardiography video loop showing a submitral diverticulum in inferior wall of left ventricle exhibiting diastolic prominence with partial systolic obliteration.

Download Video

Supplementary Video S2 Multiplanar reconstructed computed tomography video loop in vertical longitudinal axis plane showing submitral diverticulum in basal inferior segment of left ventricle showing preserved myocardial contractility.

SMDs of left ventricle are rare subtype of left ventricular diverticulum (LVD) and are presumed to be congenital in origin with preserved myocardial contractile function unlike myocardial aneurysms which often depict akinetic or dyskinetic movements. Diverticulum will show preserved myocardial layers and myocardial contractility; however, an aneurysm or pseudoaneurysm will show hypokinesia/akinesia or dyskinesia. SMDs are congenital whereas left ventricular aneurysms (LVAs) or pseudoaneurysms (LVPAs) are acquired secondary to infection, ischemia, or inflammation (HIV, tuberculosis, infective endocarditis, Takayasu arteritis, myocardial infarction).[1] In a large retrospective study of 809 patients, 354 (49.1%) had LVA, 453 (50.6%) had LVD, and 2 (0.3%) had both. LVD was most seen at left ventricle apex in 61% cases and in submitral region in 4.9% cases. Both LVA and LVD presented with ventricular tachycardia/fibrillation, syncope, and cardioembolic events in 18 to 20% cases.[2] No association with HCM is described in published literature till date. Generally, SMDs are asymptomatic; however, they can present with electrophysiological and thromboembolic consequences. Often SMDs present with re-entrant ventricular tachycardia.[3] [4] Also, secondary to its location in submitral region, it may involve mitral sub-valvular apparatus and trigger AF as seen in our case. Echocardiography and cross-sectional cardiac imaging such as CTCA and cardiac magnetic resonance imaging provide comprehensive evaluation of SMD. This case highlights important phenotypic markers in patients with HCM having electrophysiological manifestations and role of imaging in detection of such uncommon anatomical variations.

Conflict of Interest

None declared.

Data Availability Statement

All the data related to this case are available with the corresponding author and can be provided at reasonable request.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. No animals were involved.

Patient Consent

Informed consent was taken from the patient regarding use of clinical information and imaging findings for publication.

• References

• 1 Barnawi A, Al Otaibi A, Soliman A, Al Rifae M, Al Baradie A, Ghazal S. A case of submitral aneurysm presenting with severe mitral regurgitation and shock in an African male patient with rheumatic heart disease. CASE (Phila) 2021; 5 (04) 224-226
• 2 Ohlow M, Lauer B. P2105 Characteristics and outcome of congenital left ventricular aneurysm and diverticulum: analysis of 809 cases published since 1816. Eur Heart J 2017; 38 (Suppl. 01) ehx502.P2105
• 3 Yoshida T, Niwano S, Izumi T. Images in cardiology: arrhythmogenic giant submitral left ventricular diverticulum. Heart 2002; 88 (01) 52
• 4 Kumar B, Satheesh S, Selvaraj R. Submitral aneurysm in adults: a rare entity with varied presentations. Cardiovasc Case Rep 2018; 2 (02) 119-122 (CVCR)

Publication History

Article published online:
10 February 2026