CAD – Attendings Only

1A)  Answer B.  11%   The Framingham Risk Score is useful for deciding when to initiate lifestyle modification and preventive medical treatment, and for patient education, by identifying men and women at increased risk for future cardiovascular events. The first Framingham Risk Score included age, gender, LDL cholesterol, HDL cholesterol, blood pressure (and also whether the patient is treated or not for his/her hypertension), diabetes, and smoking. It estimated the 10-year risk for coronary heart disease (CHD).   It performed well, and correctly predicted 10-year risk for CHD in American men and women of European and African descent.  The updated version was modified in dyslipidemia, age range, hypertension treatment, smoking, and total cholesterol, and it excluded diabetes, because diabetes meanwhile was considered to be a CHD Risk Equivalent.

Based on the Framingham score, the patient is estimated to have an 11% 10-year risk of a coronary artery disease event.  Individuals with low risk have 10% or less CHD risk at 10 years, with intermediate risk 10-20%, and with high risk 20% or more.

1B) Answer A.  Initiate lifestyle modifications.   This patient with metabolic syndrome has an intermediate risk of coronary artery disease (CAD) in the next 10 years. Interventions to reduce his risk of future CAD events are indicated. The patient is an active cigarette smoker, his blood pressure is in the prehypertension range, and his LDL cholesterol level is elevated. Appropriate risk factor modification includes weight loss, smoking cessation, and exercise with clinical re-evaluation in 3 to 6 months.

Although this patient has prehypertension, defined as a systolic blood pressure of 120 to 139 mm Hg or a diastolic blood pressure of 80 to 89 mm Hg, pharmacologic treatment of prehypertension is not recommended and has not been shown to reduce the risk of CAD events.

Statin therapy is not indicated for this patient at this time. Although the National Cholesterol Education Program (NCEP) recommends a goal LDL cholesterol level of 130 mg/dL (3.4 mmol/L) or less for patients with an intermediate risk of CAD, this goal for this patient may be achieved with lifestyle changes. His LDL cholesterol level should be remeasured approximately 3 months after institution of these changes.

Lipoprotein(a) and homocysteine levels are considered to be conditional risk factors for CAD. The use of conditional risk factors is not currently supported or recommended for cardiovascular risk estimation. The association between conditional risk factors and CAD is limited by the lack of standardized assays, the correlation of these risk factors with other major risk factors, and a lack of randomized trials demonstrating that the treatment of these conditional risk factors reduces the risk of CAD.

Exercise stress testing is not recommended for the estimation of cardiovascular risk in an asymptomatic patient. In patients with diabetes mellitus who are beginning an exercise program, exercise testing has been recommended.

2)  Answer B.  Medical therapy for chronic stable coronary artery disease (CAD) includes both antianginal and vascular-protective agents. Antianginal therapy includes β-blockers, calcium channel blockers, and nitrates. Vascular-protective therapy includes aspirin, angiotensin-converting enzyme (ACE) inhibitors, and statins. This patient is already on a β-blocker, aspirin, a statin, and an ACE inhibitor. Switching to a long-acting nitrate will help relieve his angina symptoms. However, his resting heart rate of 85/min suggests a suboptimal dose of β-blocker, and the patient’s dosage of metoprolol should be increased. The β-blocker dose should be titrated to achieve a resting heart rate of approximately 55 to 60/min and approximately 75% of the heart rate that produces angina with exertion. The patient should be re-evaluated in a few weeks to assess the response to therapy.

Ranolazine is a novel antianginal agent that is approved for the treatment of chronic stable angina. It should only be used, however, in additional to baseline therapy with a β-blocker, a calcium channel blocker, and a long-acting nitrate. Given that this patient was on suboptimal doses of metoprolol and is just being started on a long-acting nitrate, the addition of ranolazine would be premature.

Exercise treadmill stress testing would not provide useful information in this setting. It would only confirm the high pretest probability that this patient has underlying CAD as a cause for the current symptoms. In selected patients with chronic stable angina, exercise stress testing may be useful to assess the response to medical therapy (the effectiveness of current antianginal therapy) and to objectively evaluate the severity of angina (the level of activity at which angina occurs). Given that this patient is not on maximal medical therapy, exercise treadmill stress testing would not provide additional useful information.

Coronary angiography would not be indicated at this time because the patient is not receiving maximal medical therapy. In the setting of continued angina despite maximal medical therapy, coronary angiography could be considered.

3) Answer C.  Begin simvastatin.  ACP and ACC jointly recommend that in the absence of contraindications, the following agents should be used in asymptomatic patients with CAD to prevent MI and death:
* Lipid-lowering therapy with a statin in patients with documented CAD or type 2 diabetes mellitus (level of A evidence).  The patient in this case not only has documented CAD with a drug eluting stent in place but also LDL not at goal below at least 100.  Both criteria warrant the initiation of a statin to reduce his risk of MI and death.

* Aspirin in patients with previous MI (level A evidence).
* Aspirin in patients without previous MI (level of B evidence).
* Blockers in patients with previous MI (level of B evidence)
* ACE inhibitor in patients with CAD who also have diabetes, systolic dysfunction, or both (level of A evidence).  The patient has neither diabetes nor known systolic dysfunction.

In a randomized trial that compared clopidogrel with aspirin in patients with previous MI, stroke, or symptomatic peripheral vascular disease (that is, those at risk for ischemic events), clopidogrel appeared to be slightly more effective than aspirin in decreasing the combined risk for MI, vascular death, or ischemic stroke. However, no further studies have confirmed the efficacy of clopidogrel in patients with stable angina or asymptomatic CAD; thus, clopidogrel is best reserved for patients who cannot take aspirin.

Exercise electrocardiographic testing is not indicated for routine screening of asymptomatic patients, regardless of risk of cardiovascular disease.

4)  Answer D.   Coronary artery bypass graft surgery.   This patient has several indications for coronary artery bypass graft surgery. He has stenosis of the left main coronary artery and multivessel coronary artery disease with mildly reduced left ventricular systolic function. Coronary artery bypass grafting is indicated in patients with left main coronary artery disease, severe three-vessel disease with reduced left ventricular systolic function, and severe three-vessel disease with involvement of the proximal left anterior descending artery. In addition, patients with diabetes mellitus and multivessel disease also derive benefit from coronary artery bypass graft surgery. In this setting, surgery would not only relieve angina and improve quality of life, but it would also prolong life expectancy. Patients achieve a significant clinical benefit when the left internal mamillary artery graft is used as the bypass conduit for lesions within the left anterior descending artery system.

Enhanced external counterpulsation (EECP) is an acceptable treatment for patients with medically refractory angina who are not candidates for revascularization. However, the patient presented is a candidate for coronary artery bypass graft surgery, and this should be performed prior to considering alternative options such as EECP.

Although percutaneous coronary intervention may occasionally be used for patients with multivessel coronary artery disease who are not appropriate candidates for surgery, it would not be the best choice for this patient. This patient is young and active, and he does not have any clear contraindications for surgery.

Ranolazine can be useful in patients with chronic stable angina on maximal medical therapy. However, this patient has severe obstructive coronary artery disease that requires revascularization. In patients who have failed to benefit from revascularization and remain symptomatic on maximal medical therapy, ranolazine can be considered.