Dilated Cardiomyopathy

Discussion on dilated cardiomyopathy. In MOGE(S) classification for cardiomyopathies M suffix D stands for dilated cardiomyopathy. Cardiomyopathy is a primary disorder of the heart muscle which causes abnormal myocardial performance. Dilated cardiomyopathy is characterised by progressive left ventricular dilatation and systolic dysfunction. Pathologically, there is increase in the size and weight of the heart. There is ventricular dilatation with near normal wall thickness. The myocardial systolic dysfunction is out of portion to the fibrosis. The incidence of dilated cardiomyopathy varies among different studies. One study has quoted annual incidence of 6 cases per 100,000 population. Death from progressive pump failure occurs at the rate of about 25% in first year, 35-40% in two years and up to 40-80% over five years. Stabilization may occur in about 20% of cases, but complete recovery is rare in idiopathic dilated cardiomyopathy. Familial dilated cardiomyopathy constitutes 20-35% of idiopathic dilated cardiomyopathy. Inheritance patterns vary from autosomal dominant/recessive to X-linked and mitochondrial inheritance patterns. In some families, there may be associated conduction system disease of varying severity. Mutations have been described in titin (TTN), lamin A/C (LMNA) and sodium channel (SCN5A) in familial DCM. Lamin A/C and sodium channel mutations may be associated with cardiac conduction abnormalities. Cardiomegaly on chest X-ray PA view in dilated cardiomyopathy. The cardiothoracic ratio is increased, and the right border is shifted to the right, indicating right atrial enlargement. Superior venacaval shadow is seen upwards from the right atrial contour, indicating congested superior vena cava. Sick persons may present with features of frank pulmonary edema in the form of hilar haze or bat wing pattern. Significant left ventricular dysfunction can exist without much of cardiomegaly on chest X-ray as well. ECG may show sinus tachycardia, left atrial overload and sometimes left ventricular hypertrophy. A wide QRS complex with left bundle branch block pattern may indicate potential benefit from cardiac resynchronization therapy. ECG is more useful in suggesting diseases which have to be considered in the differential diagnosis like coronary artery disease and severe aortic stenosis. Severe aortic stenosis with heart failure may not have an audible murmur due to the low output state. Holter monitoring is useful in identifying ventricular arrhythmias which will alter the prognosis, especially sustained ventricular tachycardia. Holter monitoring is indicated in those with history of palpitation, syncope and near syncope. Echocardiogram is the mainstay for the diagnosis of dilated cardiomyopathy and exclusion of other conditions. Though global hypokinesia of the left ventricle is the hallmark of dilated cardiomyopathy, some regional wall motion abnormalities may not negate the diagnosis of dilated cardiomyopathy. M-mode echocardiogram showing severe left ventricular dysfunction. A prominent B hump is seen in the mitral valve echocardiogram indicating high left ventricular end diastolic pressure. E point septal separation or EPSS is also increased. Calcium scoring is useful to differentiate ischemic dilated cardiomyopathy from the idiopathic variety. If the calcium score is negative, it is unlikely to be ischemic in origin. As no contrast injection is involved, it does not pose any risk of decompensation. Coronary angiography is considered in those with age above 40 years and a history suggestive of coronary artery disease or having a high coronary risk profile or an abnormal ECG. Limitation of activity based on functional status is recommended. Salt and fluid restriction is needed in those with systemic or pulmonary congestion. Medical therapy consists of Angiotensin converting enzyme inhibitors, diuretics, digoxin and carvedilol. Recent addition to this group are ARNI and SGLT2 inhibitors. Hydralazine/nitrate combination can be used as a vasodilator when ACE inhibitors are not tolerated or in the presence of renal dysfunction. Another alternative is angiotensin receptor blocker when the renal function is good. Anticoagulation is considered if the ejection fraction is less than 30%, when there is a history of thromboembolism and in the presence of mural thrombi. A thrombus in dilated cardiomyopathy has a higher chance for embolization than in coronary artery disease. In coronary artery disease, the thrombus is kept away from the bloodstream by a segment of myocardium which is poorly contracting while the rest of the myocardium contracts well. In dilated cardiomyopathy since the hypokinesia is global, the thrombus is within the region of the blood flow and has a higher chance for breaking off and embolization. Cardiac resynchronization therapy is useful in those with dyssynchrony as evidenced by wide QRS complex and left bundle branch block pattern on ECG.

Видео Dilated Cardiomyopathy канала Johnson Francis, MBBS, MD, DM