Non-obstructive hypertrophic cardiomyopathy, asymptomatic presentation

Jothika*

Physician Assistant, Kauvery Hospital, Hosur, Tamil Nadu

*Correspondence

Abstract

Non-obstructive Hypertrophic Cardiomyopathy (Non HCM) is a genetic cardiac disorder characterized by asymmetric septal hypertrophy and left ventricular outflow tract obstruction. We present a case of a 41- year-old male presenting with asymptomatic status

Key words: Non-obstructive Hypertrophic cardiomyopathy (Non HCM); HOCM

Introduction

HOCM is a primary myocardial disorder associated with significant morbidity and risk of sudden cardiac death.

Case presentation

A 41-year-old male came for Master Health Checkup and noticed VPC in ECG, and further evaluation of ECHO showed Asymmetrical Septal Hypertrophy, dilated LA, no RWMA, good LV function, ditastolic dysfunction grade II and trivial MR.

Was Then patient advised Holter monitoring to evaluate the VPC burden & Cardiac MRI to evaluate the percentage of scar burden evaluation.

Holter monitor report: 10% PVC, No NSVT/ VT.

Cardiac MRI report: Mixed subtype of biventricular HCM, severe burden of non-ischemic scar (30% of myocardial mass) wall thickness 29 mm in inferior septum and 15 mm apical lateralsegment.

On examination

On clinical examination, patients had no shortness of breath, no angina on exertion, no fainting, no palpitation, vitals stable, no arrhythmias.

Lab investigations

Hb114.9
TC 88041
Creatinine 0.8
TGL1623
HDL335
HbA1C55.7
Na136
K5.1
Total cholesterol193
Uric acid8.4
Urea22

ECG

ECHO

Management

Patients were evaluated with Holter monitoring and Cardiac MRI and advised for Automatic Implantable Cardiac Defibrillator (AICD), Patients underwent the procedure on 20/3/26

Medications

  • Cordarone 200 mg 1-0-0 to given (Antiarrhythmics)
  • Amlong AT 5mg (for hypertension)

Though the patient being asymptomatic, he was advised surgery in view of increased scar burden, asymptomatic septal hypertrophy of around 29mm and family history of sudden cardiac death.

Treatment

The administration of L type calcium channel blockers and of disopyramide, a negative inotropic antiarrhythmic agent, has also been beneficial. Left ventricular hypertrophy in HCM is known to be caused by myocardial hyper contractility that results from an excess of action – myosin cross bridges in the sarcomere. The inhibition of myosin ATPase has been shown to reduce this excess and thereby block the development of left ventricular hypertrophy in mouse model of HCM. Mavacamten is the first in class myosin inhibitor that has been shown, in placebo – controlled trials, to reduce outflow pressure gradients substantially and to improve exercise capacity. It has been approved.it is possible that myosin inhibitors will be disease modifying that is change its natural history.

Symptomatic patients with persistent marked obstruction despite Pharmacological treatment can be managed by septal reduction therapy – Either surgical Myectomy or alcohol septal ablation

Septal Myectomy: Septal Myectomy is surgery to thin out the wall between the left and right side of the heart, which becomes thick and obstructs blood flow in people with HCM. Thinning the septum also reduces mitral valve regurgitation, a condition in which blood flows backward into the atrium, or upper chamber of the heart. Septal Myectomy is the most performed surgical procedure for people with HCM.

Sudden cardiac death, observed most frequently in adolescents and young adults, is caused by ventricular fibrillation and as was shown by Maron et al can be prevented by implanting a cardioverter defibrillator. Patients with history of sustain or repetitive ventricular tachycardia, unexplained syncope, massive left ventricular hypertrophy and extensive late gadolinium enhancement or with a family history of this complication are at high risk and should receive such a device.

Discussion

HCM -Hypertrophic Cardiomyopathy is characterized by the presence of increased left ventricular (LV) wall thickness or mass (hypertrophy). It is genetically determined heart muscle disease most often caused by mutation in sarcomeric genes which encode proteins forming the contractile apparatus of heart, although many features of the HCM phenotype may not be attributable to sarcomere mutations. HCM is notable for the heterogeneous spectrum of its phenotypic expression, clinical course, pattern and extent of LV hypertrophy and other features such as papillary muscle and mitral valve abnormalities. It is associated with an increased risk of sudden cardiac arrhythmia, death, atrial fibrillation, thromboembolic disease, and progressive heart failure. HCM has an estimated prevalence of 1 in 500 individuals.

Individuals with HCM are often asymptomatic and diagnosed incidentally. Symptomatic patients commonly present with dyspnea, fatigue, chest discomfort, palpitation, presyncope and syncope, or sudden cardiac death (SCD). The mechanisms underlying dyspnea include elevated left ventricular end Diastolic pressure from Diastolic dysfunction, mitral regurgitation, left ventricular outflow tract obstruction (LVOTO)and ischemia. Chest discomfort results from an oxygen demand- supply mismatch, intramural compression of small arteries from myocardial hypertrophy, vascular remodeling, and abnormal coronary flow reserve. Unexplained syncope is an established risk factor for SCD.

On physical examination, the classic finding of LVOTO is mid peaking crescendo – decrescendo systolic murmur best heard at the left sternal border in patients with Obstructive HCM. A separate, distinct, mid- systolic, high- pitched, blowing systolic murmur caused by mitral regurgitation, resulting from distortion of the mitral valve apparatus related to systolic anterior motion of the mitral valve, may be best heard at the apex .

Non-Obstructive HCM may present with signs of volume overload due to a small restrictive LV, with elevated jugular venous pressure or lower extremity edema.

Conclusion

HCM has been a fascinating condition challenging cardiologist for more than 6 decades. Suspecting HCM is the first key to obtaining the proper studies to make an early diagnosis. Family screening and sudden cardiac death risk assessment are crucial for all patients diagnosed with HCM. Asymptomatic patients do not require therapy, medical therapy should be considered with Beta blockers and calcium channel blockers as first -line agents, but CMIs have been proven effective as a novel therapy for the treatment of symptomatic obstruction HCM and may delay the need for septal reduction therapy.

The wide variety of phenotypes and clinical presentations can complicate the diagnosis of HCM but, with thorough and focused diagnostic evaluation, patients can be identified and appropriately managed, minimizing their morbidity and mortality.

Reference

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  2. Maron MS,wells S . Myocardial strain in hypertrophy cardiomyopathy: A force worth pursuing? JACC cardiovasc imaging 2019 Oct; 12 (10):1943-1945 [Pub Med].
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  4. Teare, D Asymmetrical hypertrophy of the heart in young adult br Heart J. 1958-20:1-8
  5. Ommen, SR .Mital ,S Burke MA.2020 AHA/ACC guidelines for the diagnosis and treatment of patients with hypertrophic cardiomyopathy: a report of the American College of cardiology/ American Heart association joint committee on clinical practice guidelines, circulation 2020;142:e558-e631
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