12 Cardiomyopathy Dilated
57Case 12 Dilated Cardiomyopathy
Table 12.2: Causes of dilated cardiomyopathy
• Idiopathic
Table 12.1: Differences between dilated and ischemic cardiomyopathy
Dilated CMP Ischemic CMP
Hypokinesia Global Regional
RWMA and the coronary territory Do not conform Conform
Dyskinesia Not seen Seen
RV involvement Often Rare
wall while right ventricular dilatation was present (Table 12.1). Therefore, the most probable diagnosis in this case is dilated cardiomyopathy.
There are several causes of dilated cardiomyopathy (DCMP). The idiopathic variety is believed to follow an acute viral myocarditis. Prominent definite causes of DCMP are heavy alcoholism, diabetes mellitus and the peri-partum period.
Familial DCMP is seen in Duchenne’s muscular dystrophy and Friedrich’s ataxia. Deficiency of thiamine (vitamin B1), selenium and carnitine can cause a reversible form of DCMP. Drugs implicated in the causation of DCMP are doxorubicin, imatinib, cyclophosphamide and trastuzumab. Uncommonly, a per sis tent tachycardia due to any cause, can lead to permanent DCMP (Table 12.2).
PERTINENT INVESTIGATIONS
While echocardiography is a dependable diagnostic modality for dilated cardiomyopathy, a battery of tests can be performed to ascertain the etiological diagnosis. This is because there are several causes of DCMP and a vigorous search is warranted to identify a treatable cause, with the optimism of preventing relentless progression of the disease.
Inflammatory markers (ESR and CRP) are elevated in the presence of myocarditis while levels of biomarkers (CPK, LDH) are increased in myocardial necrosis. Patients are screened for a chronic infection (HIV, Hepatitis C) or nutritional deficiency (thiamine, selenium, carnitine). Serum iron, ferritin and transferrin are ordered if anemia or hemochromatosis are suspected and T3, T4 and TSH if thyrotoxicosis is to be ruled out. Renal and liver function tests are ordered to assess additional causes of fluid overload.
58 Section 4 The Cardiomyopathies
Cardiac magnetic resonance imaging (MRI) is useful to assess left ventricular size and geometry, LV remodelling and for tissue characterization with gadolinium enhancement. Coronary angiography is performed in the presence of atherosclerotic risk factors. Endomyocardial biopsy is rarely performed because of its low diagnostic yield.
MANAGEMENT ISSUES
The first step in the management of DCMP is to identify and treat reversible factors. Measures include withdrawal of the offending drug and correction of any nutritional deficiency. Abstinence from alcohol and control of diabetes are equally important. The heart rate has to be controlled in tachycardia related cardiomyopathy.
Treatment of most of these patients is on the lines of standard heart failure therapy. Diuretics are prescribed to treat fluid overload and modulators of renin-angiotensin system (ACE-inhibitors or ARBs) to reduce cardiac afterload. Beta-blockers are used particularly if extreme tachycardia or atrial fibrillation are present. If the patient has persistent atrial fibrillation, rate control with digoxin is required. Additionally, the patients are initiated on an oral anticoagulant to reduce the risk of thrombo-embolic complications.
RECENT ADVANCES
A significant proportion of patients with dilated cardiomyopathy succumb to malignant ventricular arrhythmias and not to heart failure per se. Antiarrhythmic drugs reduce ejection fraction and have proarrhythmic potential, besides their systemic side-effects. The use of automatic implantable cardioverter defibrilla-tors (AICDs) is now advocated as a primary preventive strategy against sudden cardiac death (SCD) in such patients. Anticoagulant therapy is widely prescribed to patients who are in atrial fibrillation and in those where a mural thrombus has been documented. Currently, trials are underway to evaluate the role of anticoagulants against thromboembolic complications in patients who are in sinus rhythm.
In patients with moderate to severe symptoms (NYHA Class III or IV) with severe left ventricular dysfunction (LVEF below 30%) and wide QRS complexes (QRS duration more than 120 msec), cardiac resynchronization therapy (CRT) may be offered. A biventricular pacemaker is placed to synchronize the ejection of right and left ventricles if there is left bundle branch block (LBBB) or an intraventricular conduction defect (IVCD). Finally, a ventricular assist device may be implanted to improve left ventricular function in those with significant hemodynamic deterioration. This strategy is particularly useful as a bridge to cardiac transplantation.
C A S E
13 Restrictive
Cardiomyopathy
CASE PRESENTATION
A 58-year old man presented to the cardiology facility with fatigue, difficulty in breathing and increasing swelling over his ankles, for the last 3 months. His dyspnea became worse at night and he required two or more pillows under his head to be comfortable. In addition, he had noticed an increase in his abdominal girth and had loss of appetite, but there was no weight loss. There was no history of fever, productive cough, chest pain or hemoptysis. He also denied palpitations or episodes of syncope. The patient was not hypertensive or diabetic and there was no history of premature coronary artery disease in any of his family members.
On examination, he was tachypneic but not in any distress. The pulse was 90 beats /min with a BP of 114/72 mm Hg. There was no cyanosis or jaundice but pitting edema was present around the ankles. The liver edge was palpable 6 cm below the right costal margin and there was free fluid in the abdominal cavity. The JVP was elevated 5 cm above the angle of Louis, with prominent a waves and without a fall in its level during inspiration. The apex beat was normal in character and location, without any displacement towards the axilla. The S1 and S2 were normal with an audible S4 in late diastole. There was no murmur or pericardial friction rub. Crepts were audible over the basilar lung fields posteriorly.
CLINICAL DISCUSSION
From the history and physical examination, this patient was clearly having biventricular heart failure. ECG showed low QRS voltages with non-specific T-wave changes but no Q waves. There was no tachyarrhythmia or conduction block. X-ray chest findings were interstitial pulmonary edema and small bilateral pleural effusion, but the heart size was normal. ECHO revealed relative small ventricular chambers with bilateral atrial dilatation. The ventricular free walls and the interventricular septum were thick and gave a “granular sparkling”
ground-glass appearance (Fig. 13.1). There was also thickening of the mitral and tricuspid valve leaflets with minimal valvular regurgitation. The left ventricular ejection fraction was normal but the transmitral Doppler showed a tall E-wave with rapid deceleration and a small A-wave.
There were several unusual clinical findings in this case. There was biventri-cular heart failure but no clinical or radiological evidence of cardiomegaly.
60 Section 4 The Cardiomyopathies
Prominent a waves in the JVP and presence of S4 on auscultation indicate atrial contraction against a stiff, noncompliant right ventricle. Failure of the JVP to fall during inspiration (or paradoxical rise) constitutes the Kussmaul’s sign and also indicates ventricular diastolic restriction. Despite evidence of ventricular hypertrophy on ECHO, the voltages of the QRS complexes on the ECG were low.
This indicates that myocardial infiltration was the cause of ventricular thickening in this case and not myocardial hypertrophy, as is observed in systemic hypertension and aortic stenosis. ECHO revealed relatively small ventricles and large atria, findings that are typically seen in mitral stenosis with pulmonary hypertension and secondary tricuspid regurgitation. However, in our case there was no evidence of mitral stenosis.
This patient therefore has a restrictive ventricular filling abnormality or left ventricular diastolic dysfunction (LVDD) or heart failure with preserved ejection fraction (HFPEF). Clinically speaking, the most frequent causes of LVDD are systemic hypertension and coronary artery disease, where the mitral inflow Doppler signal shows a slow relaxation pattern with the E wave shorter than the A wave. These conditions were clearly absent in our case. Therefore, the most probable diagnosis in this case is restrictive cardiomyopathy.
There are several causes of restrictive cardiomyopathy (RCMP). The most prominent cause of RCMP is endomyocardial fibrosis (EMF). Another reason is hypereosinophilic syndrome, the so called Loeffler’s endocarditis. A variety of systemic infiltrative disease such as amyloidosis, sarcoidosis and malignancy can present with RCMP. Connective tissue disorders especially scleroderma can also lead to myocardial restriction. Finally, RCMP may be observed in storage diseases like hemochromatosis and glycogen storage disorders (Table 13.1).
Amyloidosis is an important cause of restrictive cardiomyopathy. Besides cardiac involvement, there may be other systemic manifestations of amyloid deposition. Macroglossia with periorbital ecchymosis is pathognomic of amyloi-dosis. Neurological manifestations are sensory neuropathy, carpal tunnel syndrome and autonomic neuropathy with postural hypotension. Hepatomegaly may be due to amyloid infiltration or due to congestive heart failure. Renal
Figure 13.1: ECHO showing bright echogenicity with small ventricles and large atria
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