Myocardial infarction: symptoms

Symptoms of myocardial infarction

The symptoms of myocardial infarction depend to some extent on the severity and location of the arterial obstruction and are highly variable. Except in cases of extensive infarction, determining the extent of ischemia based on clinical manifestations alone is difficult.

Following acute injury, various complications may develop. They usually consist of electrical dysfunction (e.g. conduction disturbances, arrhythmia), myocardial dysfunction (heart failure, rupture of the interventricular septum or ventricular wall, ventricular aneurysm, pseudoaneurysm, cardiogenic shock), or valvular dysfunction (typically the development of mitral regurgitation). Electrical dysfunction may be significant in any form of myocardial infarction, whereas myocardial dysfunction usually requires disruption of the blood supply to large areas of the myocardium. Other complications of myocardial infarction include transient ischemia, mural thrombosis, pericarditis, and post-infarction syndrome (Dressler syndrome).

Unstable angina

The clinical manifestations are the same as those of angina pectoris, except that the pain or discomfort of unstable angina is usually more intense, lasts longer, is caused by less physical exertion, occurs spontaneously at rest (like rest angina), and has a progressive course (any combination of these features is possible).

Non-ST-elevation myocardial infarction with ST-elevation

The presentation of HSTMM and STMM is similar. Several days to weeks before the acute episode, two-thirds of patients experience prodromal symptoms, including unstable or worsening angina, shortness of breath, and fatigue. Usually the first sign of infarction is a deep, intense sensation in the chest described as pain or pressure, often radiating to the back, jaw, left arm, right arm, shoulders, or all of these areas. The pain is similar to that of angina but is usually more intense and prolonged; it is often accompanied by shortness of breath, diaphoresis, nausea, and vomiting; it is relieved only slightly and only temporarily by nitroglycerin or rest. However, discomfort may be mild. Approximately 20% of acute myocardial infarction cases are asymptomatic (either so-called asymptomatic, or the patient experiences vague sensations that he/she does not perceive as a disease); this picture most often develops in patients with diabetes mellitus. Some patients develop syncope. Patients often describe discomfort as dyspepsia, especially because spontaneous symptomatic relief may coincide with heartburn or taking antacids. Atypical variants of discomfort occur more often in women. Elderly patients may complain of shortness of breath more often than of ischemic chest pain. In severe ischemic episodes, patients often experience severe pain and anxiety. Nausea and vomiting may occur, especially in lower myocardial infarction. Dyspnea and weakness may predominate due to left ventricular failure, pulmonary edema, shock, or severe arrhythmia.

The skin may be pale, cold to the touch and moist. Central cyanosis or acrocyanosis is possible. The pulse may be threadlike, blood pressure may be variable, although many patients initially have some increase in blood pressure due to pain syndrome.

Heart sounds are usually somewhat muffled, with a fourth heart sound almost always present. A soft systolic murmur at the apex (reflecting the onset of papillary muscle dysfunction) may appear. Pericardial friction rubs and other more intense murmurs detected at initial examination suggest preexisting heart disease or another diagnosis. A pericardial friction rub detected several hours after an acute episode resembling myocardial infarction suggests acute pericarditis rather than myocardial infarction. However, a pericardial friction rub, usually short-lived, quite often appears on the 2nd or 3rd day after STHM. Tenderness on palpation of the chest wall is noted in approximately 15% of patients.

In right ventricular myocardial infarction, symptoms include increased right ventricular filling pressure, distension of the jugular veins (often with the appearance of Kussmaul's sign), clearing of the lung fields, and arterial hypotension.

Classification of myocardial infarction

Classification of myocardial infarction is based on changes in ECG data and the presence or absence of markers of myocardial injury in the blood. Dividing myocardial infarction into HSTHM and ETIM is useful because these conditions have different prognoses and treatments.

Unstable angina (acute coronary insufficiency, pre-infarction angina, intermediate syndrome) is defined as meeting the following criteria.

• Rest angina lasting more than 20 minutes.
• First-ever attack of angina pectoris (at least Canadian Cardiovascular Society functional class III).
• Worsening angina: previously diagnosed angina with increasing frequency of attacks, increasing severity and duration, occurring with less exertion (e.g. an increase of one or more functional classes or at least functional class III).

In unstable angina, changes in ECG data (segment depression, elevation, or inversion of the wave) are also possible, but these changes are transient. Of the markers of myocardial damage, no increase in CPK activity is detected, but a slight increase in troponin I is possible. Unstable angina is clinically inconsistent and can be a prelude to myocardial infarction, arrhythmias, or (less commonly) sudden death.

Non-segment elevation myocardial infarction (HSTHM, subendocardial myocardial infarction) is myocardial necrosis (proven by markers of myocardial damage in the blood) without acute segment elevation and the appearance of a pathological wave on the electrocardiogram. Segment depression, wave inversion, or both are possible.

Segment elevation myocardial infarction (STMM, transmural myocardial infarction) is myocardial necrosis with changes in ECG data in the form of a segment elevation that does not quickly return to the isoline after taking nitroglycerin, or with the appearance of a complete left bundle branch block. Pathological O waves may appear.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ]