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| EDITORIAL |
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| Year : 2001 | Volume
: 47
| Issue : 3 | Page : 163-4 |
Hypertrophic cardiomyopathy: the elusive terrorist?
Y Lokhandwala
Correspondence Address:
Y Lokhandwala
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 11832615 
Keywords: Autopsy, Biopsy, Cardiomyopathy, Hypertrophic, pathology,Human,
How to cite this article:
Lokhandwala Y. Hypertrophic cardiomyopathy: the elusive terrorist?. J Postgrad Med 2001;47:163 |
Described a century ago, hypertrophic cardiomyopathy (HCM) is a unique disease with characteristic inappropriate myocardial hypertrophy that occurs in the absence of obvious cause for hypertrophy.[1],[2],[3],[4],[5] The macroscopic and microscopic features of this disease have been under detailed study since 1950. This is particularly significant in the background of it being one of the most common genetically transmitted cardiac disorders. There is scant data regarding this in Indian literature. In this context, the present study by Phadke et al of 14 cases of HCM is commendable. Phadke et al have critically analysed the pathological data of 14 retrospective cases of HCM. Their study spans 15 years during which time they confirmed HCM in about 14% of all cases of cardiomyopathy as identified in post-mortem. The macroscopic features include marked myocardial hypertrophy with relatively small left ventricular cavity. The finding that predominant left ventricular involvement is commoner than right ventricular is commensurate with our clinical experience.
The pattern and extent of hypertrophy in HCM varies greatly from patient to patient and the characteristic feature is heterogeneity in the amount of hypertrophy evident in the different regions of left ventricle.[6],[7] A feature found in most patients with HCM is disproportionate involvement of interventricular septum and anterolateral wall compared with the posterior segment of the free wall of left ventricle. Echocardiographically, mild RV hypertrophy is very difficult to diagnose with certainty.
The cardinal microscopic features described in the literature include hypertrophy and disarray of muscle bundle.[8],[9] Fibrosis is usually prominent & may be extensive enough to produce grossly visible scars. What is unique about the disarray in HCM is its ubiquity and frequency. In the present study, they have attempted to grade the myocardial disarray & have taken it together with other features like hypertrophy, degeneration, fibrosis, inflammation and obliterative small vessel disease. Many investigators feel that myocardial disarray is not a very specific feature of HCM.[10],[11] But other investigators have suggested that myocardial disarray is a specific marker for HCM only when considered in a quantitative rather than qualitative fashion.[12],[13] They have showed that a cut off of 5% best differentiated patients with HCM from those with other cardiac diseases. Phadke et al were able to demonstrate in the present study that the disarray was quite variably distributed and often patchy and the diagnostic yield was 40-50% of an average of 20 sections. Also bizarre myocyte hypertrophy, large nuclei, myocyte degeneration, scarring and inflammatory infiltrates were usual accompaniments. Obliterative small vessel disease was present in 50% of this series as compared to >80% in some other series.[6],[14]
The clinical correlates of the hypertrophy and disarray are impaired relaxation (diastolic dysfunction), outflow obstruction and reentrant circuits. In later stages there is ventricular dilation and impaired contractility leading to heart failure. The diastolic dysfunction leads to pulmonary congestion, manifesting as dyspnea. The outflow obstruction produces giddiness on exertion and chest pain due to demand-supply mismatch. Reentrant circuits lead to ventricular tachycardia, which could sometimes be fatal. Sudden death is known and the high risk markers for this include a young age (less than 30 years) at diagnosis, family history of sudden death, history of syncope, non-sustained ventricular tachycardia on Holter, severe hypertrophy and identifiable genetic abnormalitities.
This brings us to the practical aspects of histological diagnosis. A histological diagnosis would require extensive sampling, so as to rule out false negative and false positive diagnoses. But with presently available techniques of transcatheter endomyocardial biopsy, only small tissue samples (up to four or five) are available for study. Hence everything boils down to the fact that biopsy diagnosis in life cannot really refute or confirm the diagnosis of HCM. The main role of biopsy is to provide aetiological diagnoses like amyloidosis, sarcoidosis, etc.
To conclude, the histological diagnosis of HCM can be confidently made by extensive studies at autopsy as demonstrated in this series, which is not possible with the current endomyocardial biopsy techniques. Hence the role of biopsy in the diagnosis and management of HCM at present is dubious at best. But detailed autopsy studies do help to confirm the diagnosis especially in sudden cardiac deaths so that the family members can be spared the trauma of further genetic screening.
The author acknowledges the help of Dr. P. J. Nathani, Department of Cardiology, Seth G. S. Medical College and K. E. M. Hospital for the help in writing this manuscript.
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