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Cardiomyopathy

ESC working group defines cardiomyopathy as a myocardial disorder in which there is abnormality in the structure and function of the myocytes, in the absence of coronary artery disease , hypertension , valvular heart disease and congenital heart disease that could justify this abnormality

 

American Heart Association defines cardiomyopathy as a heterogeneous group of diseases of the myocardium associated with mechanical and / or electric dysfunction that usually (but not invariably) exhibit inappropriate ventricular hypertrophy or dilatation due to a variety of etiologies that are frequently genetic

 

Non-ischaemic disease of the myocardium was conceptualized in 1889 by Fieldler – when he reported a series of fatal cases in young adults with cardiomegaly and heart failure Evans reported unexplained cardiomegaly in families Brigden – was the first to use the term cardiomegaly in 1957 to characterize patients with idiopathic myocardial disease , several among them had familial disease A WHO task force two decades later gave the first classification of cardiomyopathies based on predominant structural and hemodynamic phenotype that is 
- dilated cardiomyopathy ( DCM )
- hypertrophic cardiomyopathy ( HCM ) &
- restrictive cardiomyopathy all cardiomyopathies were initially thought to be idiopathic , but discovery in 1990 of a mutation in the beta myosin heavy chain gene led to the recognition of disease causing genes WHO took note of this and unknown was deleted from the classification and cardiomyopathy was redefined as diseases of the myocardium associated with cardiac dysfunction

 

A full knowledge of classification is not needed in primary care Previous classification by the American Heart Association was to divide them into primary and secondary The European Society of Cardiology classifies cardiomyopathies according to morphological and functional phenotype ( Elliott et al 2008 ) An easier classification for primary care physicians has been given by Vincenza et al in Acta Biomedica 2019 which classifies them as
- hypertrophic ( HCM )
- dilated ( DCM )
- left- ventricular non-compaction
- restrictive
- arrhythmogenic right ventricular

 

HCM is thought to be more prevalent in the general population than previous estimates – in fact it is the commonest known cardiovascular genetic disorder known HCM , DCM and restrictive cardiomyopathies may each present with symptoms suggestive of heart failure as reduced ejection fraction , peripheral edema , fatigue , orthopnoea , dyspnoea on exertion , paroxysmal nocturnal dyspnoea , presyncpe and cardiac ischaemia HCM is the commonest structural cause of sudden cardiac death in individuals less than 35 yrs of age including competitive athletes A diagnosis of cardiomyopathy can have a significant implication on
- occupation
- insurance
- pregnancy and childbirth
- driving 
in addition to risk of heart failure and death Epidemiological data is only available from developed countries

 

Hypertrophic cardiomyopathy is described as the presence of increased left ventricular thickness not solely explained by abnormal loading conditions
 ( European Society of Cardiology ).

Loading conditions can be aortic stenosis , hypertension or thyroid disease.

 

How common -recognised globally Houston and Stevens ( 2015 ) reported a prevalence of 0.2 % with a mortality of 1 % annually Vincenza et al report that HCM is a relatively common inherited condition with a prevalence of 1 : 500 in the population.

 

What happens -left ventricular hypertrophy without chamber dilatation septal thickening predominates and may cause LV outflow tract obstruction or mitral valve dysfunction autosomal dominant mutations of genes that code for sarcomere proteins causing myocyte disarray – hallmark of HCM ( ie 60 % of cases are familial ) 11 mutant genes with more than 500 individual transmutations- ie phenotypic diversity and variable penetrance ( means not all persons with HCM will be symptomatic ) The affected individuals are heterozygous and offspring of the affected individuals have a 50 % risk of inheriting the gene mutation, with males and females equally at risk in 5-10 % of adult cases HCM may be caused by other genetic disorders including inherited metabolic and neuromuscular diseases, chromosome abnormalities and genetic syndromes

 

Presentation – can vary from individual to individual some complain few if any symptoms and are picked up incidentally or during screening tests others may experience angina , dyspnoea , palpitations and syncope caused by dynamic LV outflow obstruction , systolic and diastolic LV dysfunction and arrhythmia key points in history
- family h/o sudden deaths
- unexplained heart failure or arrhythmias
- signs and symptoms suggesting an underlying systemic cause

 

Clinical features – jerky rapidly rising pulse prominent LV impulse apical systolic murmur (increases in intensity during Valsalva murmur ) a fourth heart sound may also be frequently heard

 

Suggested tests – ECG may show- voltage criteria for LVH , T wave inversions and Q waves Transthoracic 2-D and Doppler Echocardiography – most reliable test which confirms the diagnosis of HCM ( LV wall thickness >= 15 mm in adults ) Upright exercise testing 48 hr ambulatory ECG monitoring Cardiac MRI ( if available )

 

Genetic counselling – genetic counseling by trained professionals within multidisciplinary teams if the disease cannot be explained solely by a non-genetic cause genetic testing for those who fulfill the diagnostic criteria for HCM when it enables cascade genetic screening fr their relatives 1st degree relatives should be informed about the consequences of a diagnostic test on life insurance , pension , occupation , sporting activities and eligibility for fostering and adoption if a definite causative mutation is identified relatives should be 1st genetically tested and then clinically evaluated if they are found to carry the same mutation if genetic testing is not available or fails to identify a definite mutation 1st degree relatives – offer them ECG and echocardiogram which is then repeated every 1-2 yrs between 10-20 yrs of age and then every 2-5 years thereafter in children – consider best interest and consequences

 

Management – lifestyle measures as avoiding excess alcohol consumption , weight loss , avoiding dehydration pharmacological agents as non vasodilating beta blockers as propranolol , calcium channel blockers and diuretics septal surgical myomectomy and transcoronary alcohol septal ablation of the myocardium ICD – single most important recent advancement in management of HCM

 

 

Dilated cardiomyopathy-Characterized by dilatation of at least one ventricle and systolic dysfunction with normal ventricular wall thickness important cause of sudden cardiac death and heart failure major reason for cardiac transplantation in children and adults causes include inherited , infectious and inflammatory etiologies about 25-30 % cases are familial – it is a genetically heterogenous diseases and has different modes of inheritance most common is idiopathic variant can present at any age and is responsible for 60 % of cases of cardiomyopathy in children long latent period is common where patients may remain asymptomatic clinical signs are usually arrhythmias , thromboembolic events such as stroke and above all symptoms of heart failure

 

lifestyle recommendations pharmacological management with significant clinical benefit include ACEi , ARBs , beta blockers , aldosterone antagonists and vasodilators ICD for patients with prior cardiac arrest or sustained VT , severe systolic dysfunction

 

Restrictive cardiomyopathy – Defined by impaired diastolic function with restrictive filling and reduced diastolic volume of either or both ventricles , preserved systolic function and invariably normal or mildly increased wall thickness. least common of the major cardiomyopathies with unknown prevalence can be primary or secondary with amyloidosis , sarcoidosis , radiation therapy and scleroderma among the common causes can manifest any time from childhood ( 5 % of paediatric cardiomyopathies ) to adulthood in half the cases no cause can be found

 

Left ventricular non compaction – Disease of endomyocardial trabeculations that increases in number and prominence- leading to a typical thick spongy appearance. rare congenital cardiomyopathy can present throughout life high risk of malignant arrhythmias , thromboembolic events and left ventricular dysfunction.

 

Arrhythmogenic – Characterized by fibrofatty myocardial replacements and clinically by prominent ventricular arrhythmias and impairment of ventricular systolic function.inherited heart disease can present with palpitations and syncope , signs of ventricular failure and life threatening arrhythmias predisposes to sudden cardiac death particularly in young infants and athletes

 

Peripartum -LV systolic dysfunction at the end of the pregnancy or in the the months following delivery associated with increasing age , black race , preeclampsia , hypertension , peripartum cardiomyopathy in a previous pregnancy and multiple gestation’s presentation is with heart failure

 

Takotsubo also known as stress-induced or broken heart syndrome Other names include transient apical ballooning syndrome , apical ballooning cardiomyopathy , Gebrochenes- Herz syndrome non-ischaemic cardiomyopathy which predominantly affects post-menopausal women abrupt onset of LV dysfunction in response to severe emotional or physiologic stress characterized by transient regional systolic dysfunction of the LV in absence of angiographically significant CAD or acute plaque rupture

References

  1. Ahmad SA, Brito D, Khalid N, et al. Takotsubo Cardiomyopathy. [Updated 2020 Mar 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430798/
  2. Domenico CorradoCristina Basso, and Daniel P. Judge ( Abstract )
  3. Singh DP, Patel H. Left Ventricular Non-compaction (LVNC) Cardiomyopathy. [Updated 2020 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537025/
  4. Rammos, Aidonis et al. “Restrictive Cardiomyopathies: The Importance of Noninvasive Cardiac Imaging Modalities in Diagnosis and Treatment-A Systematic Review.” Radiology research and practice vol. 2017 (2017): 2874902. doi:10.1155/2017/2874902
  5. Mahmaljy H, Yelamanchili VS, Singhal M. Dilated Cardiomyopathy. [Updated 2020 Aug 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441911/
  6. Lakdawala, Neal K et al. “Dilated cardiomyopathy.” Circulation. Arrhythmia and electrophysiology vol. 6,1 (2013): 228-37. doi:10.1161/CIRCEP.111.962050
  7. Precone, Vincenza et al. “Cardiomyopathies.” Acta bio-medica : Atenei Parmensis vol. 90,10-S 32-43. 30 Sep. 2019, doi:10.23750/abm.v90i10-S.8755
  8.  Jarvis S (2019) Cardiomyopathies 1: classification, pathophysiology and symptoms. Nursing Times [online]; 115: 7, 38-42.
  9. Precone, Vincenza et al. “Cardiomyopathies.” Acta bio-medica : Atenei Parmensis vol. 90,10-S 32-43. 30 Sep. 2019, doi:10.23750/abm.v90i10-S.8755
  10. HCM Summary card for general practice ESC via https://www.escardio.org/static-file/Escardio/Guidelines/publications/HCM2014_ESC_HCM_Summary_Card.pdf
  11. Brieler J, Breeden MA, Tucker J. Cardiomyopathy: An Overview. Am Fam Physician. 2017;96(10):640-646
  12. McKenna WJ, Maron BJ, Thiene G. Classification, Epidemiology, and Global Burden of Cardiomyopathies. Circ Res. 2017;121(7):722-730. doi:10.1161/CIRCRESAHA.117.30971
  13. Diagnosis and Management of Hypertrphic Cardiomyopathy – Position Statement The Cardiac Society of Australia and New Zealand via https://www.csanz.edu.au/wp-content/uploads/2017/07/Hypertrophic-Cardiomyopathy_ratified_25-Nov-2016.pdf

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