Risk factors of Myocardial Infarction 2

A Majority of the risk factors associated with Myocardial Infarction can be modified and it is possible to prevent a large number of heart attacks by adopting a healthier lifestyle. The physical activity is linked with a lower risk profile. However, there are some risk factors that cannot be modified and it includes age, sex, and family history of an early heart attack. Apart from these factors, there are some socio-economic factors including the lack of proper education, lower income and unmarried cohabitation that add to the risk of MI. In order to understand the  epidemiological study results, one should note that lots of factors associated with MI express their risk via other factors. For example the income and marital status of an individual is related to the education level.

The risk of myocardial infarction is increased moderately in women who use combined oral contraceptive pills. It is compounded in presence of other risk factors such as smoking. The

inflammation is regarded as an important step in the atherosclerotic plaque formation and the presence of C-reactive protein (CRP) is a sensitive marker  for inflammation. The elevated CRP blood levels also help in predicting the risk of MI, stroke and diabetes. Inflammation in periodontal disease might be linked to coronary heart disease. The Serological studies measures the antibody levels against typical periodontitis-causing bacteria and concluded that antibodies were present in good numbers in persons with coronary heart disease. Periodontitis led to increased blood levels of CRP, cytokines and fibrinogen; therefore it may mediate its effect on MI risk via other risk factors.

Other independent risk factors for MI include the baldness, and hair greying. The presence of a diagonal earlobe crease and other skin features are also considered as independent risk factors for MI. The process of atherosclerotic plaque formation involves  the calcium deposition and it can be detected by the CT scans. The coronary calcium offers predictive information about MI that cannot be obtained from classical risk factors.

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Risk Factors of Myocardial Infarction

There are many Risk factors for Myocardial Infarction and most of them are associated with the risk factors of atherosclerosis.

Some Super Active+ Online Pharmacy of the common risk factors of Myocardial Infarction are listed below.

(1) Diabetes (with or without insulin resistance) – It is considered to be one of the major risk factor for ischaemic heart disease (IHD) that lead to Myocardial Infarction.

(2) Tobacco smoking – Tobacco is not only lethal for lungs but also it has severe harmful effects on the heart.

(3) Hypercholesterolemia – It refers to the condition of high low density lipoprotein and low high density lipoprotein.

(4) Presence of Low HDL, High Triglycerides and High blood pressure contributes to MI

(5)Family history of ischaemic heart disease (IHD) – If the individual has the IHD among its family members then it is likely to affect him as well.

(6)Obesity – the obese persons are more prone to MI because of the blood pressure related ailments in them.

(7)Age –The independent risk factor acquired by Men at the age of 45 and independent risk factor acquire by women at the age of 55. Moreover, if the individual has first degree male relatives who are suffering from coronary vascular event age 55 then he acquire an independent risk factor. Similarly, an individual acquire independent risk factor if he has first degree females who are suffering from coronary vascular event at age 65 or younger.

(8) Hyperhomocysteinemia – It is a condition marked by high levels of homocysteine which is a toxic blood amino acid.

(9) Stress is also one of the major risk factors for MI and it is more prevalent in persons with occupations of high stress index.

(10) Long exposure to high quantity of alcohol also led to increased risk of MI.

(11) It is observed from the statistics that males are more prone to MI as compared with females.

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Preventing Myocardial Infarction

Healthy lifestyle and Medication – It is possible to manage the risk factors of MI by adopting strict blood pressure management and lifestyle changes. One can decreases the risk of MI significantly by smoking cessation, limiting alcohol intake, doing regular exercise and adopting a sensible diet for patients with coronary disease. Once a patient has survived MI, he has to be treated with several long-term medications that aim to prevent secondary cardiovascular events like cerebrovascular accident (CVA), congestive heart failure and further myocardial infarctions.

Using Poly unsaturated fats – The studies have shown that the consumption of polyunsaturated fats instead of saturated fats can lead to decrease in coronary heart disease.

The usage of Antiplatelet drug therapy like aspirin and/or clopidogrel are common for preventing MI as it minimizes the risk of plaque rupture and prevent recurrent myocardial infarction. Aspirin acts as a first-line therapy as it is cheap and has good efficacy. The combination of clopidogrel and aspirin also reduces the risk associated with cardiovascular events.

Beta blocker therapy – The usage of Beta blockers such as metoprolol or carvedilol is proven to be beneficial in high-risk patients. ?-Blockers  significantly reduces the mortality and morbidity rates. They also enhance the symptoms of cardiac ischemia in NSTEMI.

ACE inhibitor therapy – The ACE inhibitors are used within 24–48 hours post-MI in hemodynamically-stable patients. It is specifically used in patients that have a history of diabetes mellitus, hypertension, MI, and left ventricular dysfunction. ACE inhibitors lead to reduction of mortality rate and it also prevent the development of heart failure, and decreases the ventricular remodelling after a patient suffered MI.

Omega-3 fatty acids are proven to reduce mortality post-MI.

Statin therapy – It is proven to reduce mortality and morbidity post-MI.

The aldosterone antagonist agent eplerenone reduces further risk of cardiovascular death post-MI in high risk patients with heart failure and left ventricular dysfunction.

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Management of Myocardial Infarction – Reperfusion

The modern treatment of Myocardial Infarction relies heavily on the reperfusion therapy. Reperfusion therapy includes the usage of Thrombolytic therapy, Percutaneous coronary intervention, Coronary artery bypass surgery and Reperfusion dysrhythmia. Patients with suspected acute myocardial infarction and ST segment elevation (STEMI) are assumed to have an obstructive thrombosis in an epicardial coronary artery. These candidates  are treated for immediate reperfusion with thrombolytic therapy and percutaneous coronary intervention (PCI). When these therapies are unsuccessful, bypass surgery is performed. The PCI or medical management is preferred over the emergency bypass surgery for the treatment of an acute myocardial infarction (MI). The primary percutaneous coronary intervention is beneficial over thrombolytic therapy for the treatment of acute ST elevation myocardial infarction.

Individuals that do not have ST segment elevation are assumed that they are experiencing either non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (UA). These patients are given initial therapies and they are stabilized with antiplatelet drugs and anticoagulated. If the condition remains stable, they are offered late coronary angiography with consequent restoration of blood flow (revascularization). These patients can also be given non-invasive stress testing for determining if there is considerable ischemia that will improve from revascularization. In case, the patients with NSTEMIs show hemodynamic instability, they may undergo urgent coronary angiography followed by revascularization. The treatment of thrombolytic agents is contraindicated in such patients.

The treatment regimens offered to the patient are based on the  ST segment elevations on an ECG that results from complete blockade of  a coronary artery. However, in case of NSTEMIs, there is narrowing of a coronary artery with diminished but still preserved flow to the distal myocardium. These patients are administered the anticoagulation and antiplatelet agents for preventing the blockade in the narrowed artery. In case of Reperfusion dysrhythmia, the presence of Accelerated idioventricular rhythm (AIVR) that looks like slow ventricular tachycardia indicates the successful reperfusion.

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Management of Myocardial Infarction – Anti Platelet Agents and Nitroglycerine

A MyocardiaI Infarction is a state of medical emergency that needs immediate medical attention. The treatment of MI is intended to prevent as much damage to myocardium as possible. The therapies are designed for preventing further complications. The most common agents  used for the management of MI include Oxygen, aspirin, and nitroglycerin. They are administered immediately as the patient arrives in the emergency department. The morphine is  used in the cases where the nitroglycerin is not effective but  it may lead to increase in mortality in the setting of NSTEMI.

Among the anti-platelet agents used, the Aspirin has been found to reduce the mortality significantly. In case a person can tolerate the aspirin, it can be taken quickly. The aspirin also exerts antiplatelet effect that inhibits the formation of further blood clots that block the arteries. The aspirin can be administered by  chewing so that it can be absorbed quickly. In addition to it, the dissolved soluble preparations and sublingual administration are also used. As per the U.S. guidelines, the recommended dosage of aspirin is 162–325 mg and Australian guidelines prescribe a dose of 150–300 mg.

Additional antiplatelet agents like clopidogrel are also used and the dosage varies as per the further treatment methods. For example, 300 mg of clopidogrel is administered orally for those patients that are receiving thrombolysis and 600 mg of clopidogrel is administerted orally in case where there is angioplasty is anticipated.

Nitroglycerin – Glyceryl trinitrate (nitroglycerin) is administered sublingually and it can also be taken Buccally if available. The Glyceryl Trinitrate acts as a donor of Nitrous oxide to smooth muscles cells that are adjacent to the coronary artery endothelium and thereby resulting in increased vasodilation and coronary blood flow. It cannot be taken if the patient has taken certain inhibitors like Viagra, Cialis, and Levitra in the last 12 hours because this combination may drastically drop the blood pressure.

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Diagnosis of MI – Physical Examination and ECG

Physical examination – During the physical examination, the appearance of patients may vary as per the experienced symptoms by them and thus patient may be restless or in severe distress or comfortable. The presence of a cool and pale skin in patients with MI is common and it highlights the vasoconstriction. The blood pressure of the patients may be high or low. The pulse of patients may be irregular and some of them may have low-grade fever (38–39 °C).

In case of a heart failure, doctor can detect the raised hepatojugular reflux and jugular venous pressure. The swelling of the legs because of peripheral edema is also found on inspection. Doctors may also inspect a cardiac bulge with different pace from the pulse rhythm on precordial examination. There could be various abnormalities detected on auscultation including systolic murmurs, paradoxical splitting of the second heart sound, third and fourth heart sound, and pericardial friction rub.

The chief aim of the electrocardiogram is to detect ischemia or acute coronary injury in case of symptomatic and broad emergency department populations. Doctors can use serial ECG for following the rapid changes happening in time. The standard 12 lead ECG does not examine the right ventricle directly, and also does not properly examine lateral and the posterior basal walls of the left ventricle. In fact, acute myocardial infarction may produce a no diagnostic ECG in the distribution of the circumflex artery. The usage of additional ECG leads including the right-sided leads and posterior leads may enhance the sensitivity for posterior and right ventricular myocardial infarction.

Patients can be classified into three groups based on the 12 lead ECG.

1. Patients with ST segment elevation

2. Patients with ST segment depression

3. Patinets with non-diagnostic or normal ECG.

A normal ECG does not mean that the patient do not have acute myocardial infarction. One should not fail to identify the high risk features.

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Diagnosis of MI – Cardiac Markers and Angiography

Cardiac markers are proteins that are secreted from the injured myocardial cells from their damaged cell membranes into the blood. The enzymes like SGOT and LDH were used till the 1980s for assessing the cardiac injury. Nowadays, the most widely used markers in detection of MI include cardiac troponins T and I; and MB subtype of the enzyme creatine kinase. These markers are more specific for indicating the myocardial injury. In fact, the cardiac troponins T and I are released within 4–6 hours of post MI and its level remains elevated for up to 2 weeks. These markers have complete tissue specificity and are ideal markers for assessing the myocardial damage.

Another marker for detecting myocardial injury is Heart-type fatty acid binding protein that is used in some home test kits. The elevated levels of troponins in the chest pain also predict a high probability of future myocardial infarction. Some other new markers include glycogen phosphorylase isoenzyme BB. The diagnosis of myocardial infarction should satisfy two out of three criteria including history, ECG, and enzymes. Following the damage to the heart, the levels of cardiac markers rises over time and because of that reason the blood tests for these markers are taken over a 24-hour interval. As the levels of enzyme take time for rise after a heart attack, patients with chest pain are treated with the assumption of myocardial infarction and evaluation is done for a more concrete diagnosis.

Angiography – The coronary angiography is performed in situations where intervention for restoring blood flow is required. The process includes the insertion of a catheter into the femoral artery and it is pushed to the blood vessels supplying the heart. Now, a radio-opaque dye is administered via the catheter followed by a sequence of x-rays (fluoroscopy). The obstructed or narrowed arteries are identified, and angioplasty is used  as a therapeutic measure. Angioplasty needs extensive skill, and it is performed by a physician who is trained in interventional cardiology.

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Diagnosis of Myocardial Infarction

The diagnosis of myocardial infarction can be done by using integrating the various methods including the physical examination, history of the presenting  illness, electrocardiogram findings and cardiac markers. By using a coronary angiogram, one can visualize the narrowing of arteries and obstructions present on the heart vessels. During the autopsy, a pathologist can diagnose a MI on the basis of anatomopathological findings.

When a patient is arrived in the emergency department, a chest radiograph and routine blood tests are performed to indicate any complications or precipitating causes. The regional wall motion abnormalities on an ECG (echocardiogram)  also suggest of a myocardial infarction. A cardiologist may perform Echo in equivocal cases. The Technetium (99mTc) sestamibi or thallium-201 chloride is used in nuclear medicine in stable patients with resolved symptoms for visualizing the areas of reduced blood flow along with pharmocologic  stress. The Thallium can also be used for determining  if the non-functional myocardium is dead or is in the state of hibernation

Diagnostic criteria of Myocardial Infarction is being formulated by WHO  in 1979 and it is followed as a classical criteria to diagnose MI if a patient satisfies two or three of the below mentioned criteria.

1. The clinical history of chest pain (ischaemic type) lasts for over 20 minutes

2. Serial ECG tracings shows changes

3. Levels of Serum cardiac biomarkers like troponin and creatine kinase-MB fraction rise and fall

The WHO criteria were modified in 2000 for giving more importance to cardiac biomarkers. As per the new refined guidelines, if a cardiac troponin rise is accompanied by pathological Q waves, coronary intervention,typical symptoms, ST elevation or depression then it is diagnostic of MI.

The early diagnosis goes a long way in preventing the MI in patients by providing them the effective treatment therapies.

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