Cardiomyopathy

Patients diagnosed with Restrictive Cardiomyopathy will present with the following signs and symptoms:

• Shortness of breath
• Exercise intolerance
• Chronic fatigue
• Paroxysmal Nocturnal Dyspnea (PND)
• Abdominal distention
• Bilateral peripheral edema
• Palpitation
• Orthostatic hypotension

Patients diagnosed with Dilated Cardiomyopathy will present with the following signs and symptoms:

• Shortness of breath
• Fatigue
• Orthopnea and PND
• Edema
• Angina
• Anemia
• Hypertension

Majority of patients with Hypertrophic Cardiomyopathy (HCM) are asymptomatic. The following symptomatology may be seen in patients with HCM:

• Dyspnea
• Pre-syncope or syncope
• Chest pain
• Orthopnea
• Dizziness
• Paroxysmal Nocturnal Dyspnea (PND)
• Palpitations
• Sudden death

The following laboratory work up and tests are done to investigate patients with impending cardiomyopathy:

• Chest X-ray – Chest radiographs will show whether the heart is enlarged.
• Echocardiography – This makes use of sound waves that determines size and functions of the heart. 
• Electrocardiogram (ECG) – This diagnostic modality uses chest electrodes to determine the electrical activity of the heart. This can detect abnormal rhythms and enlargement by voltage.
• Magnetic Resonance Imaging (MRI) – This makes use of magnetic fields and radio waves to determine a more detailed image of the heart [8].
• Cardiac Catheterization – This procedure makes use of a slender flexible tube inserted in the major vessels to the heart where a sample biopsy of the heart tissue may be taken for laboratory examination.
• Laboratory tests – blood test like the Beta-type natriuretic peptide (BNP) are tested for elevation due to heart failure which is seen as a common complication of cardiomyopathy. Troponin I may also be used to prognosticate heart failures in cardiomyopathy [9].

For restrictive cardiomyopathy, therapeutic modalities are focused on the alleviation of the symptoms. Water and salt intake monitoring is paramount to prevent overload. In some case, patients are given diuretics to unload water retention in RCM. When heart failure become progressively worse, cardiac transplant may be the only option for RCM.

Dilated cardiomyopathy are medically treated with Angiotensin converting enzyme inhibitors, Angiotensin receptor blockers, beta blockers, digoxin, and diuretics [10]. A pacemaker may be installed in patients with DCM to synchronize any irregular cardiac rhythm. Hypertrophic cardiomyopathy are given medications to relax the heart muscles like beta blockers and calcium channel blockers. Cardiac surgeries like septal myectomy and septal ablation are some of the surgical options elected to debulk the thickened muscles of the heart.

In both children and adult population the outlook for restrictive cardiomyopathy is generally poor. Most patient progress to low output heart failure which may complicate to thromboembolism or cardiac cirrhosis. There is a higher mortality rate in dilated cardiomyopathy associated with severe congestive heart failure (CHF), male sex, and increasing age. About half of the patients with DCM presenting with CHF will die within the first 5 years from diagnosis [5]. Although patients with DCM having mild CHF carries a brighter outlook. Hypertrophic cardiomyopathy carries the best prognosis with only 1-3% mortality rating [6]. Majority of the mortality seen in HCM is due to sudden death caused by ventricular tachycardia and fibrillation. Morbidity and mortality improves with early diagnosis and intervention of the HCM disease [7].

In the majority of cases of cardiomyopathy, the etiologic causation is often times unknown. The following pre-morbid causes has been implicated as the most common identifiable causes of cardiomyopathy in clinical practice:

• Heart tissue scarring from a previous ischemia
• Long standing and uncontrolled hypertension
• Valvular Heart Diseases
• Chronic Tachyarrhythmias
• Thyroid diseases
• Diabetes mellitus
• Thiamine (Vitamin B1) deficiency
• Chronic alcoholism
• Pregnancy uteri
• Illicit drug use (cocaine, methamphetamine, anabolic steroids)
• Chemotherapeutic agents for cancer
• Viral infections
• Hemochromatosis
• Genetic heart diseases

In the world wide scale, the reported incidence of cardiomyopathy is up to 400,000 to 550,000 diagnosed cases per annum prevailing in up to 5 million people. In the United States, the most common form of restrictive myocarditis is the idiopathic type. The prevalence of endomyocardial fibrosis (EMF) abounds in the subtropical areas of Africa among children and young adults [1]. Causing 25% of the deaths due to heart diseases in the same African regions.

Dilated cardiomyopathy can affect patients at any age but symptoms usually surface in the third and fourth decade of life. Hypertrophic cardiomyopathy (HCM) represents 0.5% of patient brought in for diagnostic echocardiography [2]. The worldwide prevalence rate of HCM is only 50 to 200 cases per 100,000 population [3]. HCM has a slight male predilection over the female population with a peak mean age of occurrence at the third decade of life. Although in the adult population, the majority of the diagnosed cases HCM are within the 30’s to 60’s age range.

In restrictive cardiomyopathy (RCM), the stiffness in the myocardium can give rise to an increased intra ventricular pressure even in the light of a smaller stroke volume [4]. The restrictive effect on the ventricular volume can lead to diastolic heart failure because of the progressive loss of stroke volume due to the muscular restriction. Fibrotic changes in the heart muscles can cause cardiac scarring on the heart surface and cause bundle branch block in the electrophysiology of the heart.

In the dilated cardiomyopathy cases, the ventricle begins to enlarge due to the chronic left ventricular failure causing both systolic and diastolic type of heart failures. The progressive stretch of the heart’s myocardium reduces the volume of the cardiac output contributing to the development of congestive heart failure. The progressive dilatation of the ventricles can lead to the development of an acquired tricuspid and mitral valve regurgitation defects.

The progressive hypertrophy of the heart muscles in hypertrophic cardiomyopathy increases the pressure gradient in the outflow tracts of the circulating blood. Mitral valve dysfunction happens in hypertrophic cardiomyopathy when the hypertrophy involves the heart papillary muscles and the muscular septal hypertrophy displacing the outflow tract of the mitral valve. The thickening of the heart muscles can also impair the calcium channel physiology.

In most cases, cardiomyopathy could not be prevented. Patients can only modify some activities that may result in heart failure with cardiomyopathy like abstaining from alcohol or recreational drugs. A balanced diet with adequate vitamins and minerals can actively prevent heart failure in some cases of cardiomyopathies.

Cardiomyopathy is a general term given to abnormal heart muscles. Clinically, there are basically three types of cardiomyopathies: Restrictive, Dilated, and Hypertrophic cardiomyopathy. This abnormalities seen in the heart muscles retards the normal delivery of blood throughout the organ systems of the body. Cardiomyopathy can progress to serious heart failure if left untreated. Treatment approaches to cardiomyopathy grossly depends on the type and could be therapeutically corrected by either surgical or medical means.

• Definition: Cardiomyopathy refers to any clinical disease that involves the muscles of the heart that results in the alteration in the shape and size of the myocardium.
• Cause: A number of pre-morbid causes can give rise to cardiomyopathy like hypertension, thyroid diseases, diabetes, cardiac scarring, and viral infections.
• Symptoms: Patients with cardiomyopathy will typically present with dyspnea, orthopnea, paroxysmal nocturnal dyspnea, bilateral edema, and fatigue.
• Diagnosis: Cardiomyopathy work up includes: Chest X-ray, ECG, MRI, Echocardiography, blood tests, and cardiac catheterizations.
• Treatment and follow-up: Medical treatment of cardiomyopathy includes the usage of beta blocker, digoxin, ACE inhibitors, and calcium channel blockers. Surgical cardiac muscle myectomy and ablation may also be used to debulk the heart. 

1. Braunwald E, Abelmann WH. Atlas of Heart Diseases. Vol 2. 1994:53-61.
2. Maron BJ, Peterson EE, Maron MS, Peterson JE. Prevalence of hypertrophic cardiomyopathy in an outpatient population referred for echocardiographic study. Am J Cardiol. Mar 15 1994; 73(8):577-80.
3. Maron BJ, Gardin JM, Flack JM, et al. Prevalence of hypertrophic cardiomyopathy in a general population of young adults. Echocardiographic analysis of 4111 subjects in the CARDIA Study. Coronary Artery Risk Development in (Young) Adults. Circulation. Aug 15 1995; 92(4):785-9.
4. Goldstein JA. Differentiation of constrictive pericarditis and restrictive cardiomyopathy. ACC Ed Highlights. Fall 1998; 14-22.
5. McKee PA, Castelli WP, McNamara PM, Kannel WB. The natural history of congestive heart failure: the Framingham study. N Engl J Med. Dec 23 1971; 285(26):1441-6.
6. Maron BJ. Hypertrophic cardiomyopathy: a systematic review. JAMA. Mar 13 2002; 287(10):1308-20.
7. DeRose JJ Jr, Banas JS Jr, Winters SL. Current perspectives on sudden cardiac death in hypertrophic cardiomyopathy. Prog Cardiovasc Dis. May-Jun 1994; 36(6):475-84.
8. Francone M. Role of cardiac magnetic resonance in the evaluation of dilated cardiomyopathy: diagnostic contribution and prognostic significance. ISRN Radiol. 2014; 2014:365404.
9. La Vecchia L, Mezzena G, Zanolla L, Paccanaro M, Varotto L, Bonanno C, et al. Cardiac troponin I as diagnostic and prognostic marker in severe heart failure. J Heart Lung Transplant. Jul 2000; 19(7):644-52.
10. Felker GM, Lee KL, Bull DA, Redfield MM, Stevenson LW, Goldsmith SR, et al. Diuretic strategies in patients with acute decompensated heart failure. N Engl J Med. Mar 3 2011; 364(9):797-805.