 |
I./4.3.: Course
Acute coronary syndrome is currently divided to two groups (Figure 3). The division is based on the ECG made during the first medical examination. If the ECG shows an elevation of the ST segment, it is called ST segment elevation myocardial infarction (shortly: STEMI). Similarly, a probably recent infarction with typical chest pain and an ECG showing left bundle branch block should be treated as an “ST segment elevation” acute infarction. If the ECG shows other alterations, e.g. ST depression or a change, mostly turning into negative of the T wave, or no ECG abnormity is seen at all, the correct diagnosis is non ST segment elevation acute coronary syndrome (NSTE-ACS).
Within this group (NSTE-ACS), if myocardial necrosis is demonstrated by the later performed biomarker examination, the final diagnosis is non ST segment elevation myocardial infarction (NSTEMI), while it is unstable angina pectoris if there is no elevation of necroenzyme. ST segment elevation indicates the development of transmural ischemia due to the complete occlusion of a coronary. STEMI and NSTE-ACS are different diseases from several aspects. Patients with NSTE-ACS are older and they have more severe accompanying diseases (diabetes mellitus, renal failure, heart failure, peripheral vascular disease). Also the coronary disease is more extended, severe three vessel disease is more common (i.e. several, usually multiple significant stenoses are present on the anterior descending and circumflex branches of the left coronary and on the right coronary artery – and frequently also on the main trunk).
|
 |
Nevertheless, coronary angiography not always shows a single well-defined severe stenosis or occlusion which can clearly be made responsible for the acute symptoms, but an extended ischemia (≠necrosis!) can be found as the common resultant developing due to several severe stenoses. In patients with STEMI a well defined acute coronary occlusion can be found in most cases. The prognosis of NSTE-ACS is globally not better in comparison to that of STEMI. In both cases the prognosis is determined by the size of the necrosis, which can be microscopic (focal necrosis), small (less than 10% of the left ventricle’s mass), moderate (10 to 30%), or large (more than 30%). In addition to the size of the actual necrosis, left ventricular function at the beginning of the infarction is an important anatomical aspect, as even an actually small necrosis can lead to a left ventricular function which is not compatible with life in patients whose left ventricle has already underwent a severe impairment previously.
Based on large registries, the mortality of NSTE-ACS is worse without an appropriate therapy and management of the patient, beginning from the moment of discharge from the hospital. The course of acute myocardial infarction showed a dramatic improvement in the last 40 years. In the 1960s the hospital treatment included a long bed rest, even for 6 weeks (!) and administration of heparin, morphine and nitrate. The hospital mortality corresponded to this; it was averagely about 30%. From the 1970s coronary care units began to spread, and also the defibrillators in parallel. Solely due to the availability of patient monitoring and immediate termination of ventricular fibrillation, the hospital mortality decreased to 15%.
Further significant improvement occurred from the end of the 1970s, with the era of reperfusion. In the spirit of the “theory of open coronary”, the aim was to terminate coronary occlusion in time. The first possibility of this was provided by thrombolytic therapy. Initially the thrombolytic medication was administered into the coronaries in the cardiac catheterization laboratory; obviously this was accessible only for a small number of patients. The spread of systemic intravenous administration has brought a breakthrough. Initially streptokinase from streptococcus (later produced by recombinant technique) was available. Its disadvantage was in part the relatively high number of allergies.
|
|
Thrombus-specific tissue plasminogen activators produced by recombinant technique have been available from the end of the 1980s. A further improvement in the area of life expectation was brought by the immediate coronary catheterization care, the primary percutaneous coronary intervention, by the help of which the early mortality decreased to 5-6 %. The above relate to the care of ST segment elevation myocardial infarction; in the care of non ST segment elevation acute coronary syndrome no thrombolysis was administered as it has proven to be clearly harmful in this disease, based on the relating clinical studies.
|
|