A Prospective Study of Heart Disease in Diabetes Mellitus

Abstract

Six hundred and twenty-five patients with diabetes mellitus were studied by standardised clinical methods, resting and exercise electrocardiography (ECG) and digitised echocardiography to determine the prevalence of coronary and non-coronary heart disease. Clinical evidence of coronary artery disease (angina and infarction) was present in 110 (18 per cent) normotensive patients. Hypertension (blood pressure greater than 165/95 mmHg) was present in 172 (27 per cent) of whom 32 had cardiac symptoms. Heart failure or left ventricular dilatation was seen in 18 of whom 11 had either hypertension or coronary artery disease and six asymptomatic patients had unexplained ventricular hypertrophy. Echocardiograms in 245 of 290 asymptomatic patients with normal ECG showed that relaxation was prolonged (p less than 0.001) and mitral valve opening delayed (p less than 0.001) from normal especially in those with severe microangiopathy (proliferative retinopathy and/or heavy proteinuria). The peak rates of cavity dimension increase and posterior wall thinning were reduced from normal (both p less than 0.001) and patients with severe microangiopathy had the most marked changes. Redivision of these 245 diabetics by abnormalities of left ventricular function showed that 147 had normal function in whom only one of 23 (random 15 per cent sample) had a positive exercise ECG. Prolonged relaxation or delayed mitral valve opening alone (a nonspecific abnormality) was present in 41 and only three of 28 had a positive exercise ECG. Thirty-one had delayed mitral valve opening with inco-ordinate relaxation (abnormalities very suggestive of coronary artery disease) of whom 20 of 29 had a positive exercise ECG. Twenty-six had delayed mitral valve opening with slow cavity dimension increase or wall thinning (without hypertrophy) of whom 21 of 25 had a negative exercise ECG. This is a relatively specific abnormality similar to that found in left ventricular hypertrophy. Coronary artery disease is common in symptomatic and asymptomatic forms in diabetes mellitus. Non-coronary left ventricular diseases, such as dilation and hypertrophy, are probably no more common in diabetics than non-diabetics. A small number of diabetics with severe microangiopathy had abnormal relaxation and reduced peak rate of dimension increase or wall thinning which may represent left ventricular disease due to microangiopathy.