Cardiologist in Bettahalasur, Bangalore • Aortic dissection and aneurysms A dissecting haematoma of the aortic root will cause severe chest and back pain but leads to ECG changes only if the coronary ostia are involved. The right coronary ostium is more often affected. Dissection into the coronary ostium usually causes its occlusion and results in an acute myocardial infarction. The diagnosis of dissection cannot be made from the ECG.27 There may, however, be evidence of pre-existing LVH in a high proportion of cases. Haemopericardium (tracking of blood from the dissection into the pericardial sac) is often the terminal event for these patients, but pericarditis-type ST elevation occurs only rarely. Thyroid disease Hyperthyroidism is characterised by a resting sinus tachycardia, sometimes associated with RAA. The QRS complexes and ST segments and T waves are generally unaffected but marked changes may occur, especially in acute exacerbations and ‘thyroid storms’.28 A significant proportion of patients develop AF with a rapid response, increasing with age (as Sinus tachycardia may be so marked as to be mistaken for atrial tachycardia or flutter, with potentially dangerous consequences In myxoedema there may be sinus bradycardia, sometimes with first-degree AV block, but less often than commonly thought (Fig 3.109). The most constant features are a small voltage (regardless of the presence of a pericardial effusion) and T wave flattening or shallow inversion. The QTc is prolonged. Both thyrotoxicosis and hypothyroidism can be induced by one of the most commonly used anti-arrhythmic drugs: amiodarone.29 The QT prolongation in myxoedema is unrelated to amiodarone therapy. Cardiomyopathies No distinctive ECG markers are present in myocardial disease although some patterns may be typical of the conditions in which they occur. An exception is the occurrence of LBBB with RAD in congestive (including ischaemic) cardiomyopathy , a combination not seen