CAD

Diagnosis

No single test can diagnose CHD. If your doctor thinks you have CHD, he or she may recommend one or more of the following tests.

EKG (Electrocardiogram) Stress Testing Echocardiography Chest X Ray Blood Tests Coronary Angiography and Cardiac Catheterization

Causes

Coronary artery disease is thought to begin with damage or injury to the inner layer of a coronary artery, sometimes as early as childhood. The damage may be caused by various factors, including:

Smoking High blood pressure High cholesterol Diabetes or insulin resistance Radiation therapy to the chest, as used for certain types of cancer Sedentary lifestyle

Once the inner wall of an artery is damaged, fatty deposits (plaques) made of cholesterol and other cellular waste products tend to accumulate at the site of injury in a process called atherosclerosis.

If the surface of these plaques breaks or ruptures, blood cells called platelets will clump at the site to try to repair the artery. This clump can block the artery, leading to a heart attack.

Angina is a term used for chest pain caused by reduced blood flow to the heart muscle. Angina is a symptom of coronary artery disease. Angina is typically described as squeezing, pressure, heaviness, tightness or pain in your chest.

Angina is relatively common but can be hard to distinguish from other types of chest pain, such as the pain or discomfort of indigestion. If you have unexplained chest pain, seek medical attention right away.

Angina is caused by reduced blood flow to your heart muscle. Your blood carries oxygen, which your heart muscle needs to survive. When your heart muscle isn't getting enough oxygen, it causes a condition called ischemia.

The most common cause of reduced blood flow to your heart muscle is coronary artery disease (CAD). Your heart (coronary) arteries can become narrowed by deposits called plaques. This is called atherosclerosis.

Stable angina. Stable angina is usually triggered by physical exertion.

Unstable angina. If fat-containing deposits (plaques) in a blood vessel rupture and a blood clot forms, it can quickly block or reduce flow through a narrowed artery, suddenly and severely decreasing blood flow to your heart muscle.

Unstable angina worsens and is not relieved by rest or your usual medications. If the blood flow doesn't improve, heart muscle deprived of oxygen dies — a heart attack. Unstable angina is dangerous and requires emergency treatment.

Variant angina. Variant angina, also called Prinzmetal's angina, is caused by a spasm in a coronary artery in which the artery temporarily narrows.

There are many options for angina treatment, including lifestyle changes, medications, angioplasty and stenting, or coronary bypass surgery. The goals of treatment are to reduce the frequency and severity of your symptoms and to lower your risk of heart attack and death.

However, if you have unstable angina or angina pain that's different from what you usually have, such as occurring when you're at rest, you need immediate treatment in a hospital.

MedicationsIf lifestyle changes alone don't help your angina, you may need to take

medications. These may include: Nitrates. Nitrates are often used to treat angina. Nitrates relax and

widen your blood vessels, allowing more blood to flow to your heart muscle. The most common form of nitrate used to treat angina is with nitroglycerin tablets put under your tongue.

Aspirin. Aspirin reduces the ability of your blood to clot, making it easier for blood to flow through narrowed heart arteries. Preventing blood clots can also reduce your risk of a heart attack. But don't start taking a daily aspirin without talking to your doctor first.

Clot-preventing drugs. Certain medications, such as clopidogrel (Plavix) can help prevent blood clots from forming by making your blood platelets less likely to stick together.

Beta blockers. Beta blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. As a result, the heart beats more slowly and with less force, thereby reducing blood pressure. Beta blockers also help blood vessels relax and open up to improve blood flow, thus reducing or preventing angina.

Statins. Statins are drugs used to lower blood cholesterol. They work by blocking a substance your body needs to make cholesterol.

Calcium channel blockers. Calcium channel blockers, also called calcium antagonists, relax and widen blood vessels by affecting the muscle cells in the arterial walls. This increases blood flow in your heart, reducing or preventing angina.

 

Medical procedures and surgery

Angioplasty and stenting. 

Coronary artery bypass surgery. 

Myocardial infarction or “heart attack” is an irreversible injury to and eventual death of myocardial tissue that results from ischemia and hypoxia.

Myocardial infarction is the leading killer of both men and women in the United States.

Manifestations of myocardial infarction

1. Severe chest pain and discomfort —

2. Irreversible cellular injury

3. Release of myocardial enzymes such as creatine phosphokinase

(CPK) and lactate dehydrogenase (LDH) into circulation from myocardial

damaged cells.

4. Electrocardiogram changes

5. Inflammatory response from the injured myocardium — Leukocyte infiltration, increased white blood cell counts, fever.

6. Coagulative necrosis of the area of the myocardium affected by the infarction.

7. Repair of damaged areas occurs by replacement with scar tissue and not functional muscle tissue; therefore, some alteration in function is inevitable

Laboratory tests used in the diagnosis of myocardial infarction include the following: Cardiac biomarkers/enzymes: cardiac biomarkers should be measured at presentation Troponin levels Creatine kinase (CK) levels Myoglobin levels: Complete blood count Chemistry profile Lipid profile C-reactive protein and other inflammation markers Electrocardiography The ECG is the most important tool in the initial evaluation and triage of patients in whom

an acute coronary syndrome (ACS), such as myocardial infarction, is suspected. It is confirmatory of the diagnosis in approximately 80% of cases.

Cardiac imaging

Management Prehospital care For patients with chest pain, prehospital care includes the

following: Intravenous access, supplemental oxygen, pulse oximetry Immediate administration of aspirin en route Nitroglycerin for active chest pain, given sublingually or by

spray Telemetry and prehospital ECG, if available

Emergency department and inpatient care Initial stabilization of patients with suspected myocardial infarction and

ongoing acute chest pain should include administration of sublingual nitroglycerin if patients have no contraindications to it.

The American Heart Association (AHA) recommends the initiation of beta blockers to all patients with STEMI (unless beta blockers are contraindicated).

If STEMI is present, the decision must be made quickly as to whether the patient should be treated with thrombolysis or with primary percutaneous coronary intervention (PCI).

Rationale for therapy

A main goal of intervention for myocardial infarction is to limit the size of the infarcted area and thus preserve cardiac function.

Early recognition and intervention in a myocardial infarction have been shown to significantly improve the outcome and reduce mortality in afflicted patients.

If employed in the early stages of myocardial infarction, antiplatelet-aggregating drugs such as aspirin and clot-dissolving agents such as streptokinase and tissue plasminogen activator may be very effective at improving myocardial blood flow and limiting damage to the heart muscle.

Treatment for coronary artery disease usually involves lifestyle changes and, if necessary, drugs and certain medical procedures.

Lifestyle changes Making a commitment to the following healthy lifestyle changes can

go a long way toward promoting healthier arteries: Quit smoking. Eat healthy foods. Exercise regularly. Lose excess weight. Reduce stress.

Medicines You will probably have to take several medicines that lower your risk of

a heart attack. These include: Aspirin or other antiplatelets to help prevent blood clots. An ACE inhibitor or a beta-blocker to help lower blood pressure and

reduce the workload on your heart. A statin to help lower cholesterol. To manage symptoms, you might take an angina medicine, such as

nitroglycerin. If your angina symptoms get worse even though you are taking medicines, you

may think about having a procedure to improve bloodflow to your heart. These include angioplasty  with or without stenting and bypass  surgery.

Other drugs such as vasodilators, β-adrenergic blockers and ACE inhibitors can also improve blood flow and reduce workload on the injured myocardium and thus reduce the extent of myocardial damage.

The development of potentially life-threatening arrhythmias is also common during myocardial infarction and must be treated with appropriate antiarrhythmia drugs.

Supportive therapies such as oxygen, sedatives and analgesics are also utilized.

Case 1

L.W. is a 64-year-old woman with a significant history of CAD, having had two MIs and three stent placements in the past 10 years. Her LVEF is more than 60%. She has developed shortness of breath and chest heaviness with activity during the past several months, despite being adherent to her medications.

She says she is requiring up to three doses of her sublingual nitroglycerin per day; however, she has severely curtailed her activity to avoid the discomfort. She takes aspirin 325 mg/day, simvastatin 40 mg every night, enalapril 10 mg 2 times/day, and metoprolol tartrate 50 mg 2 times/day. Her vital signs include BP 132/80 mm Hg and HR 72 beats/minute.

Which one of the following regimens is best to improve her stable angina symptoms and increase heractivity level?A. Discontinue metoprolol tartrate and begin diltiazem extended release 240 mg/ day.B. Add ranolazine 500 mg 2 times/day.C. Add isosorbide mononitrate 30 mg every morning.D. Increase metoprolol tartrate to 100 mg 2 times/day and add isosorbide mononitrate 30 mg every morning.

Answer: DBoth β-blockers and calcium antagonists can be used to achieve HR goals in patients with stable angina. However, this patient has a compelling indication for β-blockade over calcium antagonism (post-MI), and the dose can be increased.

Therefore, replacing the β-blocker with a nondihydropyridine calcium antagonist is not ideal, making Answer A incorrect. Althoughranolazine could be an option, its role remains unclear.

Although it can be used as monotherapy, it is typically prescribed as add-on therapy to maximally tolerated conventional therapy, which this patient is currently not receiving. This rationale makes Answer B incorrect. The only available option that incorporates increased HR control with β-blockade is Answer D, which also incorporates standing nitrate therapy. A

dding a nitrate by itself (Answer C) is not advisable because of thepotential for reflex tachycardia in an individual who already has a higher than desired HR. The addition of a nitrate (increased oxygen supply) and increased β-blockade (decreased oxygen demand) is the best option for this patient.

Case 2

L.J., a 58-year-old white man, is discharged from the hospital after a non-ST-segment elevation MI. His medical history is significant for hypertension. He was taking hydrochlorothiazide 12.5 mg/ day before hospitalization. An echocardiogram shows an LVEF of more than 60%.

His vital signs include BP 130/65 mm Hg and HR 64 beats/minute, and he states that he feels great. His drug regimen consists of aspirin 81 mg/day, atenolol 50 mg/day, hydrochlorothiazide 25 mg/day, atorvastatin 80 mg/day, and sublingual nitroglycerin 0.4 mg as needed for chest pain.

Which of the following represents the best action to take in response to thisdischarge regimen?A. Discontinue hydrochlorothiazide; add diltiazem extended release 240 mg/day.B. Continue hydrochlorothiazide; add amlodipine 5 mg/day.C. Discontinue hydrochlorothiazide; add ramipril 5 mg/day.D. Continue hydrochlorothiazide; add vitamin E 400 IU/day

Answer: CBecause the patient is post-MI, his BP goal is less than 130/80 mm Hg, which he has achieved. Therefore, no decision must be made on the basis of improved BP control. Because he is post-MI, he has a compelling indication for β-blocker therapy, which he is already receiving.

He has not provided any information to indicatethe need for additional antianginal therapies, so the addition of a calcium channel blocker is not necessary (Answer A and Answer B).

He is taking appropriate antiplatelet and cholesterol-lowering drugs according to the requirements for individuals with CAD. An ACE inhibitor is indicated in all patients with CAD unless a contraindication exists.

Ramipril is reasonable to add to this patient's regimen, and discontinuing hydrochlorothiazide may be desirable to minimize the occurrence of hypotension, making Answer C correct.

Vitamin E therapy is not recommended in patients with CAD because of the lack of benefit in this patient population (Answer D).