Search

Diabetes mellitus is one of the main risk factors of coronary atherosclerosis. The relative risk of cardiovascular disease is 2 to 4 times higher in type II diabetes than in the general population. The number of cases, especially type II, is increasing, especially as the definition of diabetes has been changed recently by the specialist scientific societies (American Diabetic Association, World Health organisation and ALFEDIAM) to include all patients with fasting glucose levels > or = 7 mmol/L on two occasions. Therefore, in the next 25 years, the number of diabetic patients will probably double, not only because of this new definition but also because of the combined effects of an ageing population, dietary changes (with an increase in obesity) and a progressively more sedentary and urbanized life-style in the so-called "emerging" countries.

The present interest in myocardial contrast echocardiography is related to the development of new contrast agents which can be used intravenously and the perfection of new echocardiographic technologies. Amongst the potential applications of this technique, the study of myocardial perfusion in the acute phase of myocardial infarction is one of the most promising as shown by the experience acquired over several years with intracoronary contrast echocardiography. It allows assessment of the extent of the zones at risk before recanalisation, the presence of collateral vessels and, above all, the quality of myocardial reperfusion. The demonstration of the absence of effective reperfusion of the myocardial microcirculation, or the phenomenon of no-reflow, is one of the main advantages of contrast echocardiography and has been identified as an important independent prognostic factor. This technique could therefore become essential in the evaluation of methods for reducing the extent of microvascular damage. Although many questions remain unanswered about the ideal methods of performing and analysing intravenous contrast echocardiography, the preliminary results confirm the potential of the technique in non-invasive evaluation of myocardial reperfusion in the acute phase of myocardial infarction.

Diabetes mellitus is associated with increased risk of short and long-term complications after balloon angioplasty. In patients with multivessel disease, there may be a substantial increase in long-term mortality when percutaneous transluminal coronary angioplasty (PTCA) is preferred over surgery in patients who are amenable to both techniques, which should lead to caution in selecting PTCA as a routine revascularization method for these patients. However, many diabetic patients will still require revascularization with PTCA, either for single-vessel disease or because they are poor surgical candidates. Finally, the impact of recent advances, such as stents and glycoprotein IIb/IIIa inhibitors, on the short and long-term results of percutaneous interventions is still not fully defined and deserves further study.

Complete coronary reperfusion after thrombolysis or primary angioplasty is associated with limitation of infarct size and conservation of left ventricular function. The area of viable myocardium recovers its function secondarily, the amount of recovery being related to the precocity of reperfusion. Patients with a patent artery in the acute stage do not all recover segmental contraction to the same extent. There are considerable discrepancies between coronary patency and myocardial perfusion. Myocardial perfusion, measured in the acute phase by myocardial contrast echocardiography is the best predictor of preservation of function. This suggests that microvascular lesions are a sign of the extent and irreversibility of myocardial damage. Modern treatment of infarction should not only restore coronary patency but also ensure effective myocardial reperfusion. The factors which determine recovery of ventricular function after reperfusion during the acute phase, are, in addition to early and complete coronary recanalisation and effective myocardial reperfusion: short duration of ischaemia, small size of the area at risk, collateral circulation, ability of the myocardium to withstand ischaemia, limitation of reperfusion injury. Other factors (smoking, pre-infarction angina, the occluded artery or method of reperfusion) may play a role but the role of confounding factors is always difficult to exclude.