Myocardial infarction, together with the unstable angina pectoris are part of a group of diseases referred to as acute coronary syndromes (ACS). Depending on the changes that occur in the electrocardiogram (ECG) at rest, acute coronary syndromes may be with segment elevation or without ST segment elevation.
ACS with the ST segment elevation is represented by the myocardial infarction.
ACS without ST segment elevation shows the same clinical and biological changes as ACS with the ST segment elevation, but without ST segment elevation on the ECG.
Unstable angina differs from ACS without ST-segment elevation in the absence of increased cardiac enzymes.
At the appearance of the unstable angina, atherosclerosis is involved in the process. Atherosclerosis is a chronic disease that mainly affects the arteries of medium size or large arteries and involves lipid deposition with the formation of atheroma plaque on blood vessel walls. These plaques narrow the vascular lumen, so their presence reduces the amount of blood that gets to perfuse an organ, and represents the risk of breaking. The rupture of the atheroma plaques causes the activation of inflammatory and coagulation mechanisms at appearance at the plaque level of a thrombus (blood clot) that can obstruct completely or incompletely the vascular lumen. When the lumen of a cardiac artery is completely obstructed – occurs myocardial infarction, when the obstruction is incomplete – occurs SCA without ST-segment elevation or unstable angina.
At a patient with severe coronary artery (coronary arteries – the arteries that supply the heart) through atherosclerosis, so a patient, who shows a reduction of the vascular lumen through the atheroma plaque, there are also other factors, except the rupture of the atheroma plaque, which can favor an unstable angina:
Factors that cause increased oxygen demand on the heart: fever, tachycardia, severe hypertension, hyperthyroidism, aortic stenosis, arteriovenous shunts, administration of cocaine, amphetamines.
Factors that decrease blood oxygenation in the whole body: anemia, hypotension.
Risk factors for unstable angina serve too many risk factors of atherosclerosis and coronary artery disease. There are risk factors linked to the patient’s genetic field and lifestyle:
The male sex. Women have a lower risk up to the onset of menopause due to estrogen protective action;
Heredity (first or second degree relatives with heart disease);
Older age (> 55 years for men,> 65 for women);
Obesity, excessive caloric intake of refined sugars, saturated fats, alcohol;
Social factors: professions with high responsibility, high level of stress.
Other conditions that favor atherosclerosis:
High blood pressure;
renal impairment, hyperuricemia;
Systemic inflammatory diseases: rheumatoid arthritis, lupus erythematosus, Kawasaki disease, arteritis Takayashu.
Chest pain is the classic manifestation of unstable angina. Compared with the pain of stable angina pectoris, unstable angina pain is prolonged (> 20 min) and more severe, requiring administration of multiple doses of nitroglycerin or longer periods of rest for improvement. Unstable angina can be de novo, may be aggravated (or precipitated by factors which modify the balance of intake to myocardial oxygen consumption) or can occur after myocardial infarction.
Typically, the pain of angina is described as a feeling of tightness, constriction located precordial or retrosternal, which may radiate to the left upper limb, the shoulders, the jaw, chest toward the rear, and can be accompanied by other manifestations: nausea, sweating , abdominal pain, dyspnea (shortness of breath), syncope (loss of consciousness). There atypical presentation as epigastric pain, indigestion onset, chest pain, pleuritic chest pain, progressive dyspnea. Atypical forms occur more frequently in people aged between 25 and 40 years or over 70 years in diabetic patients.
Note that the differential diagnosis between unstable angina and ACS without ST-segment elevation cannot be made based only on the basis of clinical symptoms or electrocardiogram. The only method of differentiation is emphasizing the myocardial necrosis by dosing the cardiac biomarkers.
Clinical examination of the patient
Clinical examination of the patient is usually normal. May be present signs of heart failure or signs of peripheral arterial disease (for example the murmur at the carotid artery level, femoral) indicating a greater probability of coronary atherosclerotic damage.
Note that in examining a patient with unstable angina is very important the disease history, such as elderly patients with multiple cardiovascular risk factors (diabetes, hypertension, hypercholesterolemia) or a history of myocardial infarction or myocardial revascularization surgery or stenting, have a higher probability of presenting unstable angina.
Electrocardiogram (ECG) according to current guidelines this should be done in the first 10 minutes of the pain appearance. ST segment changes and T waves are most common, but a normal ECG does not exclude the diagnosis of unstable angina. Patients with unstable angina should be monitored continuously in terms of electrocardiography as dynamic ECG changes may occur, or may be transient or intermittent. Not a rule, but ECG changes suggest that the coronary artery is effective.
Cardiac enzymes: are represented mainly by troponin and creatine kinase along with the creatine kinase MB, their growth shows installation of myocardial necrosis. In unstable angina enzymes are normal.
Cardiac ultrasound: evaluates the kinetic (movement) myocardial, left ventricular function, investigate the existence of other valvular pathologies. In case there is myocardial ischemia can be highlighted kinetic disorders (certain segments of the cardiac muscle do not have a normal contraction).
Noninvasive cardiac stress tests: refers to the various methods of assessment of myocardial oxygenation, such as exercise tests or tests with certain medicinal substances for patients who cannot make the effort. These tests are not contraindicated in patients with unstable angina who are employed in low or intermediate risk classes (does not experience pain in the last 12 to 24 hours, no signs of heart failure). Early exercise test has an important role in making the differential diagnosis with other pathologies or in determining prognosis.
Coronary angiography: an invasive diagnostic method that must be carried out in the cardiac catheterization laboratory and allows accurate visualization of the coronary arteries. Except employed patients in high risk, coronary angiography should not be performed immediately. This procedure allows besides getting a different diagnostic and therapeutic procedures of certainty as coronary obstruction with balloon or stent placement at the stenosis level from the coronary arteries.
Other imaging methods: computed tomography and cardiac nuclear magnetic resonance to visualize the heart and coronary arteries.
Chest pain or symptomatology similar to unstable angina can occur in many other heart diseases and extra-cardiac pathologies. Clinical suspicion should always be complemented by laboratory investigations to confirm the diagnosis. Differential diagnosis can be made with the following conditions:
Heart disease: myocarditis, pericarditis;
lung disease: pulmonary embolism, pulmonary infarction, pneumonia, pneumothorax, pleural effusion;
Hematologic Diseases: Anemia;
Vascular diseases: aortic dissection, aortic aneurysm;
Diseases Gastrointestinal: esophagitis, ulcers, pancreatitis, cholecystitis;
Orthopedic Diseases: rib fractures, various inflammations.
A patient with unstable angina should be continuously monitored in a coronary care unit.
1. General measures:
at ease, mobilization will be allowed after 12-24 hours without chest pain;
oxygen-therapy, depending on the case;
Pain relief: through the administration of nitrates, beta blockers, or morphine’s.
2. Medicinal treatment has two goals: prevents thrombus formation in the ruptured atheroma plaque (anticoagulant and antiplatelet therapy) and angina relief (ischemic therapy):
Anticoagulant therapy: the first priority represents the medical treatment in unstable angina. There are many treatment options available, choosing a particular preparation should take into account the indications and contraindications that the patient show, risk class that fits and the treatment strategy (invasive or conservative). Anticoagulation therapy is interrupted every 24 hours if it performs interventional procedures or at hospital discharges, if it addresses a conservative strategy (medication only).
Antiplatelet therapy must be associated with anticoagulant therapy. Usually aspirin + clopidogrel combination is given, but there are other options available. Diabetic patients, assign to a higher risk, require more potent preparations. Antiplatelet therapy is interrupted only in case of major surgical interventions or some life-threatening bleeding.
Beta blockers: ameliorates myocardial oxygenation (acting on blood pressure, heart rate and cardiac contractility) and they decrease long-term mortality. In the absence of contraindications, all patients should receive beta-blocker therapy. The best medicines in this class are metoprolol, atenolol, bisoprolol. A beta-blocker treatment is effective when resting heart rate is between 50-60 beats / minute.
Nitrates: does not influence long-term mortality, but have an important role in the symptomatic treatment – it handles attacks of angina. They can be administered orally, transdermally or intravenously.
Calcium channel blockers: does not influence long-term cardiovascular mortality. Are indicated to symptomatic patients with not sufficiently controlled with nitrates and beta-blocker, or patients who have contraindications to beta-blocker treatment. It is recommended calcium channel blockers to patients with a particular form of angina – Angina Prinzmetal (due to a vascular spasm).
Antiarrhythmic: unstable angina in patients who is complicated with cardiac rhythm disturbances, Amiodarone administration is recommended. It is not recommended prophylactic administration of antiarrhythmic drugs (mortality increase).
Converting enzyme inhibitors are long-term indications in all patients with left ventricular ejection fraction <40%, in patients with diabetes, hypertension, or chronic kidney disease in the absence of contraindications.
Angiotensin receptor blockers (the sartans) may be used in the same conditions as ACE inhibitors.
Aldosterone receptor antagonists (for example, spironolactone) can be used in patients already treated with ACE inhibitors and beta blockers and who have an ejection fraction lower than <40% and either diabetes or heart failure, with normal renal function, or near normal, without hyperkalemia.
Statins: are given precocious treatment for unstable angina regardless of cholesterol levels in all categories of patients.
3. Interventional treatment is represented by percutaneous transluminal angioplasty (PTCA) with stent implantation. Decision of adopting a precocious intervention treatment must be made taking into account the risk class that fits the patient. Unequivocally must be adopted in patients with recurrent symptoms or ischemia induced by exercise tests. Risk patients for PTCA, or patients who fall into a class of low risk may opt for conservative medical treatment. PTCA has an efficiency of 83-93% with decrease or disappearance of ischemic episodes. The type of stent to be implanted “bare metal stent” or “drug eluting stent” deciding adjustable single coronary lesion severity and the state concerned.
4. Surgical treatment consists of myocardial revascularization by coronary artery bypass grafting and is usually recommended in patients with unstable angina and multiple coronary lesions and impaired left ventricular function. In patients with single-vascular stenting incriminated vessel was the first option. In patients with multi-vessel disease, the decision PTCA or coronary artery bypass graft should be individualized. Optimal timing of interventional revascularization differs from the surgical treatment, so if PTCA is recommended to be performed as early bypass should be done after a few days of stability under medication.
Evolution and complication
Patients with unstable angina are at risk of complications due to:
Basic disease – atherosclerosis. In the absence of adequate treatment of unstable angina evolution is to myocardial infarction and all complications arising from it (ventricular arrhythmias, pulmonary edema, death);
Antiaggregant and anticoagulant therapy: bleeding and thrombocytopenia. Risk factors for bleeding are older age, female gender, other bleeding events in the past, using a class of medicines called monoamine GPIIb / IIIa. If they are not persistent minor bleeding does not require discontinuation of antiaggregant and anticoagulant treatment. Major bleeding such as gastrointestinal, retroperitoneal, intracranial hemorrhage or major blood loss requires interruption of antiplatelet and anticoagulant therapy and neutralization. The risk of acute thrombotic events after discontinuation of medication is maxim at 4-5 days, but persisted up to 30 days.
Measures to follow long-term
Reducing the weight: it has a positive impact on the subsequent evolution of the disease. Theoretical target is to achieve a body mass index less than 25 kg/m2, or a waist circumference of <102 cm in men and <88 cm in women. A weight reduction at the beginning by 10% compared Initial weight is considered the first step in achieving these goals.
Controlling the blood pressure: therapeutic target is to obtain a blood pressure <140/90 mmHg in non-diabetic patients and <130/80 mmHg in patients with diabetes or chronic kidney disease.
Treatment of diabetes mellitus in diabetic patients is recommended to obtain a glycosylated hemoglobin of <6.5%. Besides medical treatment, in obtaining this therapeutic targets is very important the change in your lifestyle and dietary.
The control of blood lipids: is ideal to maintain a level of LDL cholesterol <100mg/dl, optional <70 mg / dl. Current guidelines recommend that first intention to associate the statins with the diet, to which can be added adjustable single administration of another lipid-lowering agent. For example, nicotinic acid has a role in increasing HDL cholesterol. There are studies showing that raising HDL cholesterol with each 1 mg / dl is associated with a 6% decrease in the risk of death from myocardial infarction or ischemic heart disease.
Giving up smoking: it is difficult to achieve, for a long-term resumption of smoking being common. Often it is necessary to enable counseling and sometimes adding adjunctive therapy (Ex. nicotine patches).
Diet: is essentially a low intake of salt and saturated fat. It encourages the consumption of fruits and vegetables.
Physical activity: Regular physical activity is recommended (30 minutes of moderate physical activity per day), daily if possible, or at least 5 times a week. It is necessary to assess the functional capacity of patients with ischemia testing (for example stress test) within 4-7 weeks after an acute coronary event. Physical activity (leisure time occupation, sexual activity should be resumed) gradually and progressively increased over time.
Regular cardio-logical dispensary.
Bibliography: 1. Braunwald's Heart Disease; 2. Harrison's Principles of Internal Medicine; 3. European Society of Cardiology - Clinical Practice Guidelines.