Myocardial infarction: treatment

Treatment of myocardial infarction is aimed at reducing damage, excluding ischemia, limiting the infarction zone, reducing the burden on the heart and preventing or treating complications. Myocardial infarction - an emergency medical situation, the result depends largely on the speed of diagnosis and therapy.

Treatment of myocardial infarction is carried out simultaneously with the diagnosis. It is necessary to provide reliable venous access, give the patient oxygen (usually 2 liters through the nasal catheter) and start monitoring the ECG in one lead. Pre-hospital activities in the emergency phase (including ECG, chewing acetylsalicylic acid, early thrombolysis performed at the earliest opportunity, and transportation to the appropriate hospital) can reduce the risk of mortality and complications.

The first results of the study of cardiospecific markers help identify low-risk patients with suspected ACS (for example, patients with initially negative cardiospecific markers and ECG data) who can be admitted to a 24-hour observation unit or cardiac center. Patients with higher risk should be referred to a department with the possibility of monitoring or a specialized cardiac resuscitation unit. There are several generally accepted scales for risk stratification. The risk scale for thrombolysis during myocardial infarction is probably the most common. Patients with suspected HSTHM and moderate or high risk should be hospitalized in the cardiology department. Patients with STHM are referred to a specialized OKP.

In terms of routine long-term monitoring, heart rate, heart rate and ECG data in one lead are indicative. However, some clinicians recommend routine monitoring of ECG data in many leads with continuous ST- segment registration , which allows tracking of transient changes in this segment. Such symptoms, even in patients who do not complain, indicate ischemia and help identify high-risk patients who may need more active diagnosis and treatment.

Qualified nurses are able to recognize the occurrence of arrhythmia according to ECG data and begin treatment according to the appropriate protocol. All employees should be able to carry out cardio-recreational activities.

Concomitant diseases (eg, anemia, heart failure) also need to be actively treated.

The ward for such patients should be quiet, calm, preferably with single rooms; it is necessary to ensure confidentiality in the implementation of monitoring. Usually, visits and phone calls to family members are limited during the first few days. The presence of wall clocks, calendars and windows help the patient to navigate and prevent the feeling of isolation as well as the availability of radio, television and newspapers.

Strict bed rest is mandatory in the first 24 hours. On the first day, patients without complications (for example, hemodynamic instability, ongoing ischemia), as well as those who successfully recovered myocardial blood supply with fibrinolytic drugs or NOVA, can sit on a stool, begin passive exercises and to use a nightstand. Soon, they allow walking to the toilet and doing a relaxed job with documents. In the case of ineffective restoration of blood supply or the presence of complications, patients are prescribed a more prolonged bed rest, but they (especially the elderly) should start moving as soon as possible. Prolonged bed rest leads to a rapid loss of physical abilities with the development of orthostatic hypotension, decreased efficiency, increased heart rate during exercise, and increased risk of deep vein thrombosis. Longer bed rest also increases the feeling of depression and helplessness.

Anxiety, mood changes and negative attitudes are quite common. Often, in such cases, appoint light tranquilizers (usually benzodiazepines), but many experts believe that such medications are very rarely needed.

Depression develops more often by the 3rd day of the disease and (almost in all patients) during recovery. At the end of the acute phase of the disease, the most important task is often to remove the patient from depression, to rehabilitate and to implement long-term preventive programs. Excessive insistence on resting in bed, inactivity and stressing the severity of the disease strengthens the depressive state, so patients should be advised to sit, get out of bed and start accessing physical activity as soon as possible. With the patient you need to talk in detail about the manifestations of the disease, the prognosis and the individual rehabilitation program.

It is important to maintain the normal functioning of the intestine by prescribing laxatives (for example, bisacodyl) to prevent constipation. The elderly often have a delay in urine, especially after several days of bed rest or against the appointment of atropine. Sometimes you may need to install a catheter, but more often the condition is resolved by yourself, when the patient rises or sits down on the toilet.

Since smoking in the hospital is prohibited, staying in a hospital can help stop smoking. All the attendants should constantly adjust the patient to complete quitting.

Despite the fact that almost all patients in acute condition have a poor appetite, tasty food in a small amount maintains a good mood. Usually, a light diet is prescribed (from 1500 to 1800 kcal / day) with a decrease in sodium intake to 2-3 g. In those cases where there are no signs of heart failure, a sodium restriction is not required after the first 2 or 3 days. Patients are prescribed a diet low in cholesterol and saturated fat in order to teach the patient a healthy diet.

Since chest pain associated with myocardial infarction usually disappears within 12-24 hours, any chest pain that stays longer or appears again is an indication for an additional examination. It can indicate complications such as ongoing ischemia, pericarditis, pulmonary embolism, pneumonia, gastritis or ulcers.

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

Medications for myocardial infarction

Usually, antiplatelet and antithrombotic drugs are used to prevent the formation of blood clots. Often add anti-ischemic drugs (eg, beta-blockers, nitroglycerin intravenously), especially in those situations where chest pain or AH persists. Fibrinolytic agents are sometimes prescribed for STMM, but they worsen the prognosis for unstable angina or HSTMM.

Pain in the chest can be suppressed by the appointment of morphine or nitroglycerin. Morphine intravenously from 2 to 4 mg with repeated administration after 15 minutes if necessary is very effective, but can inhibit breathing, reduce myocardial contractility and is a powerful venous vasodilator. With arterial hypotension and bradycardia after the use of morphine can be fought by a rapid rise of hands up. Nitroglycerin initially given sublingually, and then, if necessary, continue to inject it intravenously drip.

When entering the admissions department in most patients, blood pressure is normal or slightly increased. During the next several hours the blood pressure gradually decreases. With long-persistent AH prescribed antihypertensive drugs. Nitroglycerin is preferred intravenously: it lowers blood pressure and reduces the workload on the heart. Pronounced arterial hypotension or other signs of shock are menacing symptoms, they must be intensively suppressed by intravenous injection of liquids and (sometimes) vasopressor drugs.

Antiaggregants

Examples of antiplatelet agents are acetylsalicylic acid, clopidogrel, ticlopidine and IIb / IIIa inhibitors of glycoprotein receptors. First, all patients receive acetylsalicylic acid in a dose of 160-325 mg (regular tablets, not a quick-dissolving form), if there are no contraindications. Then this drug is prescribed to them 81 mg once a day for a long period. Chewing the tablet before swallowing speeds up absorption. Acetylsalicylic acid reduces both short-term and long-term mortality risks. If this drug can not be prescribed, you can use clopidogrel (75 mg once a day) or ticlopidine (250 mg 2 times a day). Clopidogrel has largely replaced ticlopidine, since there is a risk of developing neutropenia when ticlopidine is prescribed, so regular monitoring of the number of white blood cells in the blood is necessary. Patients with unstable angina or HSTMM who are not scheduled for early surgical treatment are prescribed acetylsalicylic acid and clopidogrel at the same time for at least 1 month.

IIb / IIIa inhibitors of glycoprotein receptors (abciximab, tirofiban, eptifibatid) are powerful antiplatelet agents, administered intravenously. Most often they are used with NOVA, especially when installing stents. The results are best if these drugs are administered at least 6 hours before NOVA. If NOVA is not performed, glycoprotein receptor IIb / IIIa inhibitors are prescribed to patients at high risk, especially those with an increased number of cardiospecific markers, to patients with persistent symptoms, despite adequate drug therapy, or a combination of these factors. The administration of these drugs is continued for 24 to 36 hours and angiography is performed before the end of the administration time. Currently, routine use of inhibitors of IIb / IIIa glycoprotein receptors with fibrinolytic agents is not recommended.

[9], [10], [11]

Antithrombotic drugs (anticoagulants)

Usually, low-molecular forms of heparin (LMWH) or unfractionated heparin are prescribed, if there are no contraindications (for example, active bleeding or previous use of streptokinase or ani-streplazy). With unstable angina and HSTMM, you can use any drug. With STMM, the choice depends on the way myocardial blood supply is restored. When unfractionated heparin is used, control of activated partial thromboplastin time (APTT) is necessary for 6 hours, then every 6 hours until 1.5-2 times the control time; At the appointment of LMWH, a study of APTTV is not necessary.

Available in the US fibrinolytic drugs

Characteristic	Streptokinase	Nystreplase	Alteplase	Tenecteplase
Dose for intravenous administration	1,5х10 6 units for 30-60 minutes	30 mg in 5 minutes	15 mg bolus, then 0.75 mg / kg over the next 30 minutes (maximum 50 mg), then 0.50 mg / kg for 60 min (maximum 35 mg) to a total dose of 100 mg	Calculated by weight of the body bolus once for 5 seconds: <60 kg-30 mg; 60-69 kg-35 mg; 70-79 kg-40 mg; 80-89 kg-45 mg; > 90 kg - 50 mg
Half-life, min	20	100	6th	The initial half-life is 20-24 min; the half-life of the remaining amount is 90-130 minutes
Competitive interaction with sodium heparin	No	No	Yes	Yes
Allergic reactions	Yes Expressed	Yes Expressed	Rarely Moderately	Rarely Moderately
Frequency of intracerebral hemorrhage,%	0.3	0.6	0.6	0.5-0.7
The frequency of myocardial recanalization in 90 min,%	40	63	79	80
The number of lives saved per 100 patients treated	2.5	2.5	3.5	3.5
Dose value	Inexpensive	Expensive	Very expensive	Very expensive

Enoxaparin sodium - LMWH of choice, it is most effective at the beginning of the introduction immediately upon delivery of the patient to the clinic. Nadroparin calcium and sodium tepidarin are also effective. The properties of hirudin and bivalirudin, new direct anticoagulants, require further clinical study.

[12], [13], [14], [15], [16], [17],

Beta-blockers

These medicines are not prescribed only if there are contraindications (such as bradycardia, cardiac blockade, arterial hypotension or asthma), especially in high-risk patients.

B-adrenoblockers reduce heart rate, blood pressure and contractility, thus reducing the workload on the heart and the need for oxygen. Intravenous administration of b-adrenoblockers in the first few hours improves prognosis, reducing the size of the infarction zone, the frequency of relapses, the number of ventricular fibrillations and the risk of mortality. The size of the infarction zone largely determines the cardiac function after recovery.

During treatment with b-adrenoblockers, careful monitoring of blood pressure and heart rate is necessary. With the development of bradycardia and arterial hypotension, the dose is reduced. The expressed side effects can be completely eliminated by the administration of the β-adrenergic isoprotenol agonist at a dose of 1-5 μg / min.

[18], [19], [20], [21], [22], [23], [24]

Nitrates

Some patients are prescribed short-acting nitrate-nitroglycerin to reduce the load on the heart. This drug expands the veins, arteries and arterioles, reducing pre- and postnagruzku on the left ventricle. As a result, the need for myocardium in oxygen decreases and, consequently, ischemia. Intravenous nitroglycerin is recommended for the first 24-48 hours in patients with heart failure preceding extensive myocardial infarction, persistent discomfort in the chest, or AH. Blood pressure can be reduced by 10-20 mm Hg. St., but not below the systolic 80-90 mm Hg. Art. Longer use may be indicated for patients with recurrent chest pain or persistent congestion in the lungs. In patients at high risk, the administration of nitroglycerin in the first few hours contributes to a reduction in the infarction zone and a short-term, and perhaps even a remote, risk of mortality. Nitroglycerin is usually not prescribed to low-risk patients with uncomplicated myocardial infarction.

Other drugs

ACE inhibitors have been shown to reduce the risk of mortality in patients with myocardial infarction, especially with anterior myocardial infarction, heart failure or tachycardia. The greatest effect is noted in patients at the highest risk in the early period of recovery. ACE inhibitors are prescribed 24 hours later and after thrombolysis; due to the long-term positive effect they can be used for a long time.

Angiotensin II receptor blockers can be an effective alternative for patients who can not take ACE inhibitors (eg, due to coughing). Currently, they are not considered first-line drugs in the treatment of myocardial infarction. Contraindications include arterial hypotension, renal failure, bilateral stenosis of the renal arteries and allergies.

Treatment of unstable angina and myocardial infarction without ST segment elevation

The medicinal substances are administered as described above. You can use LMWH or unfractionated heparin. Some patients can also perform NOVA (sometimes CABG). Fibrinolytic drugs are not prescribed for unstable angina or HSTHM, since the risk outweighs the potential benefit.

Percutaneous surgery on coronary arteries

Emergency PTCA is usually not prescribed for unstable angina or HSTHM. However, the early implementation of angiography with PEA (if possible within 72 hours after admission to hospital) is indicated in high-risk patients, especially those with hemodynamic instability, a marked increase in the content of cardiospecific markers, or both, and those with symptoms persisting against the maximum drug therapy. This tactic improves the result, especially when also inhibitors of IIb / IIIa glycoprotein receptors are used. In patients with moderate risk and with ongoing myocardial ischemia, early angiography is useful in identifying the nature of the lesion, assessing the severity of other changes and functions of the left ventricle. Thus, the potential feasibility of performing NOVA or CABG can be clarified.

Treatment of unstable angina and myocardial infarction with ST-segment elevation

Acetylsalicylic acid, b-adrenoblockers and nitrates are administered in the same manner as described above. Almost always apply heparin sodium or LMWH, and the choice of the drug depends on the option of restoring the blood supply to the myocardium.

With STMM, rapid restoration of blood flow to the damaged area of the myocardium due to HOBA or fibrinolysis significantly reduces the risk of mortality. Emergency CABG is the best method for approximately 3-5% of patients with widespread coronary artery disease (identified during emergency angiography). The question of CABG should also be considered in situations where NOVA was unsuccessful or can not be performed (for example, with acute coronary dissection). Provided that experienced surgeons perform CABG with acute STMM, the death rate is 4-12% and the recurrence of the disease in 20-43% of cases.

Percutaneous surgery on coronary arteries

Provided that in the first 3 hours after the debut myocardial infarction by experienced personnel NOVA is more effective than thrombolysis and serves as the preferred option for restoring myocardial blood supply. However, if the implementation of NOVA within this time interval is impossible or there are contraindications to its implementation, intravenous fibrinolytic therapy is used. In some situations with a "light" version of NOVA before it is performed thrombolysis. The exact time interval in which it is necessary to perform thrombolysis before NOVA is not yet known.

Indications for the implementation of delayed HOBA include hemodynamic instability, contraindications to thrombolysis, malignant arrhythmias requiring implantation of EKS or repeated cardioversion, age over 75 years. The question of performing NOAA after thrombolysis is considered if, 60 minutes or more after the onset of thrombolysis, chest pain or segment elevation on the electrocardiogram persists, or they are repeated, but only if NOVA can be performed earlier than 90 minutes after the resumption of the symptomatology. If NOVA is not available, thrombolysis can be repeated.

After HOBA, especially if a stent is installed, additional therapy with abciximab (a priority inhibitor of IIb / IIIa glycoprotein receptors) is shown, which lasts 18-24 hours.

Fibrinolytics (thrombolytics)

Restoration of blood supply to the myocardium due to the action of thrombolytic drugs is most effective in the first few minutes or hours after the debut of myocardial infarction. The earlier the onset of thrombolysis, the better. The target time from admission to the administration of the drug is from 30 to 60 minutes. The best results are obtained in the first 3 hours, but the drugs can be effective up to 12 hours. Nevertheless, the introduction of fibrinolytics by trained ambulance staff before hospitalization can reduce the treatment time and also improve it. When used with acetylsalicylic acid, fibrinolytics reduce hospital mortality by 30-50% and improve ventricular function.

Electrocardiographic criteria for thrombolysis include segment elevation in two or more adjacent leads, typical symptoms and the first left bundle branch blockade, as well as a posterior myocardial infarction (high R wave in V and segment depression in V3-V4 leads confirmed by ECG at 15 leads). In some patients, the most acute phase of myocardial infarction is manifested by the appearance of giant T-wave . Such changes are not considered indications for emergency thrombolysis; The ECG is repeated after 20-30 minutes to determine if the ST segment has risen.

Absolute contraindications to thrombolysis are aortic dissection, pericarditis, hemorrhagic stroke (at any time), ischemic stroke during the previous year, active internal bleeding (not menstrual) and intracranial swelling. Relative contraindications include arterial pressure more than 180/110 mm Hg. Art. (on the background of antihypertensive therapy received), trauma or extensive surgical intervention within the previous 4 weeks, active peptic ulcer, pregnancy, hemorrhagic diathesis, and hypocoagulation state (MHO> 2). Patients who received streptokinase or anestreplase, these drugs are not reassigned.

Tenteplase, alteplase, reteplase, streptokinase and anestreplase (uninsulated plasminogen-activator complex), administered intravenously, are plasminogen activators. They convert single-chain plasminogen to double-stranded, which has fibrinolytic activity. The drugs have different characteristics and dosage regimens.

The most recommended tenecteplase and reteplase, since tenecteplase is administered with a single bolus for 5 s, and reteplase - with a double bolus. Reduction of the duration of administration leads to a reduction in the number of errors compared to other fibrinolytics having a more complex dosing regimen. Tenteplase, like alteplase, has a moderate risk of intracranial hemorrhages, a higher rate of recovery of the patency of the vessel compared to other thrombolytics, but they have a high cost. Reteplase creates the greatest risk of intracerebral hemorrhages, the frequency of restoring the permeability of the vessel is comparable to tenecteplase, the cost is high.

Streptokinase can cause allergic reactions, especially if it has been prescribed before, in addition, the time of its administration is from 30 to 60 minutes; however, this drug has a low risk of developing intracranial hemorrhages and is relatively inexpensive. Anistreplase in comparison with streptokinase gives the same frequency of allergic complications, costs a little more, but it can be administered with a single bolus. None of these drugs require the concomitant administration of heparin sodium. The frequency of recovery of the permeability of the vessel in both preparations is inferior to other activators of plasminogen.

Alteplase is administered in an accelerated version or by continued injection up to 90 minutes. The combined administration of alteplase with intravenous administration of heparin sodium increases efficacy, is not allergenic, and has a higher incidence of vascular permeability compared to other fibrinolytics, but is expensive.

[25], [26], [27], [28], [29], [30],

Anticoagulants

Intravenous management of unfractionated heparin or LMWH is prescribed to all patients with STMM, except those who are administered streptokinase or alteplase, and if there are other contraindications. In the appointment of heparin sodium APTT is determined after 6 hours and further every 6 hours to an increase in the index of 1.5-2 times compared with the control. LMWH does not require the definition of APTT. Administration of anticoagulant can be continued for more than 72 hours in patients with a high risk of thromboembolic complications.

LMWH sodium enoxaparin used with tenecteplase has the same efficacy as unfractionated heparin and is economically viable. Large studies of the combined use of sodium enoxaparin with alteplase, reteplase or CHOVA were not performed. The first subcutaneous injection is performed immediately after intravenous administration. Subcutaneous administration is continued until revascularization or discharge. In patients older than 75 years, the combined use of sodium enoxaparin and tenecteplase increases the risk of hemorrhagic strokes. For these patients, the use of unfractionated heparin in a dose calculated according to the body weight of the patient is preferred.

The use of intravenous sodium heparin with streptokinase or alteplase is not currently recommended. The potential benefits of subcutaneous administration of heparin sodium in comparison with the absence of thrombolytic therapy have not been clarified. However, in patients at high risk of systemic embolism [eg, with extensive myocardial infarction, thrombosis in the LV, atrial fibrillation (MA)], intravenous administration of sodium heparin reduces the number of possible thromboembolic events.

[31], [32], [33], [34], [35], [36]