In a myocardial infarction – colloquially called a heart attack – (synonyms: AMI; Acute myocardail infarction; Coronary infarction; Coronary insult; Myocardial infarction; ICD-10-GM I21.-: Acute myocardial infarction), death of heart muscle tissue (myocardium) occurs as a result of impaired blood flow to the heart. The destruction of the heart muscle tissue is largely irreversible, i.e. the dead cells can no longer be renewed. Myocardial infarction is one of the most common causes of death in industrialized countries. In the majority of cases, the “classic” type 1 infarct is present, which is based on a thromboembolic event (see “Classification” below). Acute myocardial infarction (heart attack) can be classified on the basis of the ECG (electrocardiogram: recording of the electrical activity of the heart muscle) as follows:
- Non-ST-segment-elevation myocardial infarction (NSTEMI; English : non ST-segment-elevation myocardial infarction).
- ST-elevation myocardial infarction (STEMI; ST-segment-elevation myocardial infarction).
The term acute coronary syndrome (AKS; acute coronary syndrome, ACS) includes:
- Unstable angina pectoris (iAP; “chest tightness”; sudden onset of pain in the region of the heart; unstable angina, UA) – unstable angina pectoris is said to occur when the symptoms have increased in intensity or duration compared with previous angina pectoris attacks
- Acute myocardial infarction (heart attack):
- Non-ST-segment-elevation myocardial infarction (NSTEMI; English : non ST-segment-elevation myocardial infarction; NSTE-ACS).
- ST-segment-elevation myocardial infarction (STEMI; engl.)
Early myocardial infarction is said to occur in men before the age of 40 and in women before the age of 45. In such cases, there are often genetic causes.Silent myocardial infarction is spoken of when it has no or no clear symptoms and therefore goes unnoticed. The prevalence of silent myocardial infarction is highest in the elderly. For further classification of myocardial infarction, see “Classification.” Sex ratio: men to women is 2: 1. Frequency peak: The risk of myocardial infarction increases significantly in men from age 40 and in women from age 50, peaking in both men and women in the 65- to 74-year-old age group. The following is a summary of the lifetime prevalence (incidence of disease throughout life) of myocardial infarction in adults aged 40-79 years by age and sex:
| 40-49 years[%] | 50-59 years[in %] | 60-69 years[in %] | 70-79 years[in %] | Total[in %] | |
| Women(n = 3,073) | 0,6 | 0,1 | 4,7 | 6,0 | 2,5 |
| Men(n = 2,766) | 2,3 | 3,8 | 11,9 | 15,3 | 7,0 |
| Total(n = 5,389) | 1,5 | 2,0 | 8,2 | 10,2 | 4,7 |
Each year, approximately 280,000 people in Germany suffer a myocardial infarction. More than three quarters of patients with myocardial infarction before the age of 55 are smokers. Furthermore, the presence of hypercholesterolemia and a positive family history is more suggestive of myocardial infarction at a younger age. The incidence (frequency of new cases) is 250-300 cases per 100,000 population per year in Germany, as well as in North America, Austria, the Netherlands, and Poland. Geographic variations in incidence are large:
- Japan: <100 per 100,000 population/year.
- Mediterranean countries, Switzerland, France: 100-200 per 100,000 inhabitants/year.
- Denmark, Scandinavia: 300-400 per 100,000 inhabitants/year.
- Ireland, England, Hungary: 400-500 per 100,000 inhabitants/year.
- Northern Ireland, Scotland, Finland: > 500 per 100,000 inhabitants/year.
Course and prognosis: The first two hours after the onset of myocardial infarction are crucial for the further course and the chances of survival of the affected person. The majority of deaths occur during this period.If immediate measures (percutaneous coronary intervention (PCI) or thrombolysis with drugs) are taken quickly to restore blood flow to the blocked vessel, the myocardium (heart muscle), which is undersupplied with blood, is not permanently damaged. After a myocardial infarction, monitoring in the intensive care unit is required because there is usually a high cardiovascular postinfarction risk and secondary prevention (prevention of a new infarction) is necessary. In differentiating type 1 infarct patients (most common form of infarction), only the presence of relevant coronary stenoses seems to be of importance with regard to risk profile and prognosis. Type 1 and type 2 infarction (see “Classification” below) are prognostically comparable in the absence of obstructive coronary artery disease (coronary artery disease with partial or complete vessel occlusion).Patients with type 2 infarction or nonischemic myocardial damage (myocardial damage not due to reduced blood flow) had a higher in-hospital mortality than patients with type 1 infarction (17.9% versus 14.0%). In contrast, the risk of cardiovascular mortality (cardiovascular-related mortality) was increased by 68% after type 1 infarction. Patients with nonischemic myocardial damage had a higher risk of death from any cause (+43%) but a lower risk of cardiovascular-related death (-57%). Long-term prognosis (here, a mean of three years) was as follows: type 1 infarct had a mortality of 31.7%, type 2 infarct had a mortality of 62.2%, and patients with nonischemic myocardial damage had a mortality of 58.7%. Patients who had their first acute myocardial infarction at age younger than 50 years had left ventricular dysfunction (LVEF/ejection fraction (also expulsion fraction) of the left ventricle at a heart beat <50%) in approximately 30% of cases. More than 40% of them showed LVEF recovery, which was associated with relatively low all-cause and cardiovascular mortality (mortality rate due to diseases of the cardiovascular system). The lethality (mortality related to the total number of people with the disease) in acute myocardial infarction is approximately 50%. Two-thirds of these deaths occur before hospital admission.Hospital mortality was 4.1% in women and 3.6% in men (no statistical difference) in a study of more about 30,000 people with the disease. However, women under 50 who have a myocardial infarction are more likely than men to die in subsequent years.Even one year after myocardial infarction, the risk of cardivascular events is still 20% for a period of 36 months.Women have a 1.5-fold higher mortality risk (risk of death) in the first year after a myocardial infarction than men with a comparable history.In patients with myocardial infarction with non-obstructive coronary arteries/non-obstructed coronary arteries (Engl. myocardial infarction with non-obstructive coronary arteries (MINOCA), 18.7% of patients had a repeat major adverse cardiovascular event (MACE) within 1 year and the 1-year mortality was 12.3%; myocardial infarction patients with macroscopic coronary obstruction/coronary artery occlusion (MICAD) had MACE in 27.6% of cases and the 1-year mortality was 16.7%. The 5-year mortality of patients with ST-elevation myocardial infarction (STEMI) is highly dependent on successful performance of catheter intervention (PCI) in the acute treatment of infarction. Acute patient mortality was 8.4%, and after five years, 21.3% of patients had died. Predictors of increased long-term mortality risk were age > 75, impaired renal function with creatinine levels > 2 mg/dl, and infarct size with CK levels > 3,000 U/I. In silent myocardial infarction, 5-year mortality is significantly higher than in those without signs of infarction (13 versus 8%); after 10 years, infarct mortality is nearly equalized (49 versus 51%).
