Coronary artery disease and atrial fibrillation

Coronary artery disease (CAD)

CASE 1 Corinne Watson (Part 1)

Corinne Watson is an 80-year-old African-American woman who lives alone and is completely independent in her activities of daily living (ADLs) and her instrumental activities of daily living (IADLs). She always comes to your office accompanied by her daughter. You see her now because of recent dyspnea and fatigue on walking to the bathroom of her home; this has occurred four times in the past week. The dyspnea is relieved by rest and is not accompanied by chest pain. Ms. Watson’s medical history is positive for hypertension, diet-controlled type 2 diabetes mellitus, and degenerative joint disease of the knees and hip that is treated with acetaminophen. Her average blood pressure in your office has been in the range of 146/85 mmHg. She has been fairly compliant with your treatment program of low-salt diet, triamterene-hydrochlorothiazide (37.5/25 mg) daily, and amlodipine 5 mg daily. Two months ago her blood count, urinalysis, electrolytes, electrocardiogram, and chest x-ray examination (CXR) were normal. Physical examination shows the following: weight 10 lbs over ideal weight; blood pressure 150/82, pulse regular (52 per minute), respiratory rate 16, no signs of congestive heart failure (CHF), an S₄ gallop, good distal pulses, and good nutrition of the skin of the feet.

1. Is this an emergency?

2. Which facts suggest a cardiovascular cause for Ms. Watson’s symptoms?

3. What social factors should influence your thinking?

4. What do you do (and say) next?

Prevalence and impact

Coronary artery disease (CAD) is so prevalent in older persons that it should be considered as a primary, contributing, or potentially complicating factor in many clinical scenarios encountered by primary care clinicians in their care of older patients. The 6% of Americans older than 75 years of age account for 60% of the CAD-related deaths.¹^,²

Recent data suggest that clinically recognized myocardial infarctions constitute only one half of those with evidence of a scar on magnetic resonance imaging (MRI). In a group of Icelanders aged 67 to 93 without diabetes, 9% had a recognized infarct, 23% had infarcts by MRI.³ A similar ratio was seen in those with diabetes. The impact of these “subclinical infarcts” remains to be determined but these findings are consistent with the high prevalence of CAD in this population.

A note about the evidence base in CAD: Caution should be exercised in interpreting the level of evidence for published articles regarding treatment, as well as guidelines published by various highly respected organizations. We and others recommend caution because very few (and sometimes no) older patients were included in the studies cited and guidelines often do not apply to older patients who have multiple interacting medical problems. We do not cite level of evidence for this reason. As always, the results of studies and guidelines offered should be noted, but their application to a specific older patient must be left to the clinician’s judgment.¹^,²

Many respected studies and guidelines do not apply to the multiple-problem older patient!

Risk factors and pathophysiology

Risk factors for CAD have been well defined although calculation of absolute risk in the elderly, especially older women, may not be as accurate as it is for middle-aged people ⁴^,⁵ (Box 37-1). In older persons, the etiology of CAD is almost always atherosclerosis. Age is so important to the chance of developing CAD that a normotensive, normal lipid, nonsmoking 80-year-old man has a slightly higher risk than a 40-year-old hypertensive, hypercholesterolemic, inactive, diabetic male smoker. Other than for hypertension, the proportion of those older than age 75 who have the other risk factors decreases prominently.¹^,² Whether CAD produces angina pectoris, unstable angina pectoris, myocardial infarction (the last three combined are called acute coronary syndrome [ACS]), or sudden death depends on the extent of the coronary obstruction, which is determined by the following pathologic features: atherosclerosis, propensity of the atherosclerotic plaque to incite platelet aggregation and clotting, the degree to which the blood itself is prone to clot formation (hypercoagulable states), and the cardiac workload (demand).

BOX 37-1 RISK FACTORS FOR CORONARY ARTERY DISEASE

Age

Gender (male/female disparity narrows with age)

Hypertension

Diabetes mellitus

Left ventricular hypertrophy on ECG

Hyperlipidemia

Smoking

Elevated homocysteine ¹

Obesity

Metabolic syndrome ² (central obesity, blood pressure ≥130/85, insulin resistance, dyslipidemia (increased triglycerides, decreased HDL)

Sedentary lifestyle

Lipoprotein abnormalities ³ with normal total cholesterol (small dense LDL, increased lipoprotein(a), increased postprandial VLDL and IDL)

Use http://hin.nhlbi.nih.gov/atpiii/calculator .asp?usertype=pub to calculate risk score, although this tool is less accurate in patients older than 80 years.

ECG, Electrocardiogram; HDL, high-density lipoprotein; IDL, intermediate-density lipoprotein; LDL, low-density lipoprotein; VLDL, very-low-density lipoprotein.

Age is such a dominant risk factor that it alone, in the absence of other risk factors, should make one consider CAD. Atypical symptoms of angina pectoris are more common with increasing age. In cognitively impaired patients, anxiety or poorly described distress may be the presenting symptom.

Differential diagnosis and assessment

Angina pectoris

Angina pectoris, sometimes called silent ischemia, in CAD is well described, but the clinical diagnosis of CAD requires an index symptom or symptoms. The index symptom of angina pectoris—as classically described—is chest pain (CP). Less than 50% of older patients have the chest pain typical of angina pectoris.⁵^,⁶ Commonly, it is dyspnea, fatigue, diaphoresis, nausea, or syncope—without chest pain—that is the index symptom of CAD in older patients, especially elderly patients with diabetes (Table 37-1).

TABLE 37-1

Presenting Symptoms of Angina Pectoris in the Old

	Classical	Atypical
Chest pain	Present	Absent
Pain radiating to jaw or arm	Often present	Absent
Sweating	Often present	Absent
Dyspnea	Often present	Often the only symptom
Fatigue	Often present	May be the only symptom
Syncope or presyncope	Atypical	May be the only symptom
Symptoms related to exertion and relieved by rest	Present	Present

The broader differential diagnosis of angina pectoris is outlined in Box 37-2. Initial tests when the clinical diagnosis is angina pectoris are listed in Box 37-3 along with notes on the rationale for ordering them.

BOX 37-2 CONSIDERATIONS IN THE DIFFERENTIAL DIAGNOSIS OF CHEST PAIN

• Ischemic cardiovascular disease

• Acute MI, unstable angina, and stable angina pectoris

• Nonischemic cardiovascular disease

• Dissecting or atherosclerotic aortic aneurysm, mitral valve prolapse, hypertrophic cardiomyopathy, pericarditis

• Gastrointestinal disorders

• Esophageal spasm, reflux, cholecystitis, peptic ulcer disease

• Musculoskeletal disorders

• Cervical disk disease, costochondritis, fibrositis

• Pulmonary diseases

• Pleuritis, pulmonary embolus, neoplasm, pulmonary hypertension

• Psychiatric illnesses

• Anxiety disorders and depression

MI, myocardial infarction.

BOX 37-3 STUDIES TO CONSIDER IN PATIENTS NEWLY DIAGNOSED WITH ANGINA PECTORIS

• To exclude associated acute myocardial infarction

• Troponin I, total CK, MBCK, and ECG

• If dyspnea a prominent symptom, assess for CHF

• BNP, echocardiogram

• If needed to exclude chest pain arising from GI tract

• Ultrasound of gallbladder, esophagram, UGD

• If statins are being considered for therapy

• LFTs, CK, aldolase

• To confirm diagnosis and quantify risks of adverse CAD events

• CRP, pulse oximetry, CBC

• Exercise or pharmacologic stress test

• Echo (for wall motion abnormalities)

• Coronary angiography

BNP, brain natriuretic peptide; CBC, complete blood count; CHF, congestive heart failure; CK, creatine kinase; MBCK, myocardium-based creatine kinase; CRP, C-reactive protein; ECG, electrocardiogram; GI, gastrointestinal; LFTs, liver function tests; UGD, upper gastro duodenal endoscopy.

CASE 1 Corinne Watson

Discussion

Ms. Watson has important risk factors for CAD: age, hypertension, and diabetes mellitus. Your first consideration should be CAD. Given this history of risk factors coupled with recent onset of dyspnea on ordinary exertion, CAD must be considered as the most likely diagnosis. CHF is unlikely on the basis of physical examination, but you will order a CXR and a brain natriuretic peptide (BNP) test. Remember, “silent” myocardial infarctions (MIs) are common in older persons, especially those with diabetes. The patient’s anginal equivalent (dyspnea) is not rapidly increasing nor severe and prolonged, excluding, on clinical grounds, ACS or unstable angina pectoris.

Underlying pulmonary disease as a cause of intermittent dyspnea is unlikely, and previous chest x-ray films are normal. Pulmonary emboli may deserve consideration but are not your first concern in the overall setting. Anemia as a cause of dyspnea is unlikely, but you will do another blood count just to be sure.

Regarding social factors, Ms. Watson lives alone and is a somewhat unwilling patient, but has a concerned daughter nearby.

Ms. Watson has stable vital signs and is in no distress now. She walks 100 feet in your office suite, which does not produce dyspnea or pain. There is no indication for hospitalization at this point.

1. What is the cardiovascular working diagnosis at this point?

2. Are there still some potential noncardiovascular diagnostic possibilities?

3. What are your next steps?

Severe (or unrecognized) dementia may prevent the patient from giving an accurate history; it may also affect their ability to understand your questions.

CASE 1 Corinne Watson (Part 2)

Ms. Watson’s diagnosis is now angina pectoris caused by CAD. Although the prognosis is relatively good at the moment, because patients with CAD may sustain unpredictable, sudden changes in the coronary circulation, leading to unstable angina, MI, or sudden death, you obtain permission from Ms. Watson to include her daughter in the discussion of diagnosis, prognosis, and treatment. You have previously determined that Ms. Watson has the capacity to make judgments for herself. You ask about treatment preferences. She wants to be resuscitated in case of a cardiac arrest but declines for the moment either stress testing or coronary angiography. In these circumstances, there is no immediate necessity for cardiac consultation.

Discussion

In addition to routine studies of blood and urine and a CXR, other tests are indicated. It is helpful to have the results back before the patient leaves your office. In patients where there is more uncertainty about the diagnosis, you may want the laboratory tests back in 1 to 2 hours or you may choose to send the patient to an emergency room. At this point, office or ambulatory care (and home care) could be safe and sufficient.

CASE 1 Corinne Watson (Part 3)

Ms. Watson’s blood count, urinalysis, and CXR are normal. The ECG is unchanged from previous tracings, showing nonspecific ST and T wave changes in the lateral chest leads. Normal values for troponin I, creatine kinase (CK), C-reactive protein (CRP), liver function tests (LFTs), and BNP are returned in 2 hours. The homocysteine level will be sent to your office in the morning. You are now anticipating that Ms. Watson will not need hospitalization. You schedule a right upper quadrant (RUQ) ultrasound (US) even though cholecystitis is not high on the list of differential diagnoses. If the patient had not declined to have stress testing, you would have ordered it. Her average blood pressure is 146/85 mmHg.

1. Which antihypertensive agent(s) would be the best choices(s) and why?

2. What approaches are indicated for Ms. Watson’s diabetes and general health?

3. Are more cardiovascular medications indicated at this point? If so, which ones and why?

Discussion

Raised BP

Because of the elevated blood pressure, a beta-blocker is a consideration, given the diagnosis of CAD, but the heart rate is 53 per minute. The amlodipine could be increased, but adding an angiotensin-converting enzyme (ACE) inhibitor or substituting it for the amlodipine is a better choice because ACE inhibitors offer beneficial effects for the diabetic kidney and the heart compromised by CAD, in addition to reducing blood pressure.⁷ Because coronary perfusion is dependent on diastolic pressure, diastolic hypotension should be avoided.

Diabetes mellitus.

Weight loss and (eventually) exercise will be good first steps in treating a patient with CAD. If the HbA_1C is not 6.0 or lower, an oral agent such as glipizide should be considered, remembering that the adverse effects of hypoglycemia may be greater in those with heart disease.

Nitrates.

A long-acting nitrate (isosorbide mononitrate 20 mg twice a day) and nitroglycerin 0.4 mg sublingually for dyspneic episodes should be prescribed, after instructing the patient to sit or lie when taking the first several doses of nitroglycerin. A visiting nurse should monitor the blood pressure and pulse, both sitting and standing, at home, to determine if this dose of isosorbide mononitrate causes postural or sustained hypotension.

Statins.

In the presence of diabetes, overweight, and age, it is unlikely that the lipids in Ms. Watson’s case will be too low to start a statin now. Statins decrease low-density lipoprotein (LDL), raise high-density lipoprotein (HDL), stabilize atherosclerotic plaques, and may even cause them to regress.⁸ In addition, statins have a beneficial effect on endothelial function, promoting coronary flow.

Aspirin.

A daily 325-mg aspirin (ASA) helps protect against untoward cardiovascular events such as heart attack and stroke. A smaller dose of ASA (100 mg/day) has been found to be effective in reducing risk of stroke, but not of cardiovascular events, in women.⁹

Ivarbradine.

Ivarbradine acts to slow the heart rate and has been used to decrease symptoms in patients over 80 with angina.¹⁰ Drugs in this class can produce syncope or other manifestations of bradycardia in the elderly. Two other agents, nicorandil and ranolazine,¹¹ have good potential to assist in angina management in the elderly, but their roles need to be further clarified in studies of the elderly with CAD.

Exercise.

Ms. Watson should continue her usual activities to the extent that they do not produce dyspnea (or chest pain).

Diet.

An American Diabetes Association diet to slowly reduce overweight and get patients down to their ideal weight should be used. The diet should also meet American Heart Association recommendations for total fat and cholesterol intake, but should give enough for nutritional content for the patient’s needs. Folic acid will reduce the concentration of homocysteine, but, unfortunately, does not alter the cardiovascular risk.¹²