Define patients who may benefit from a cardiology consultation for possible coronary angiography or revascularization.

The safe use of beta-blockers in patients with moderate or severe CHF requires careful monitoring of symptoms and dose titration; this is best done by a clinician experienced in the therapy of such patients. i.e., a cardiologist or an internist specializing in the treatment of heart failure.

Patients at high risk for death or MI may benefit from a cardiology consultation to optimize medical therapy and consider the risks and benefits of a revascularization procedure. Such patients include those with the following symptoms:

• Moderate/severe LV dysfunction
• Persistence of CHF symptoms and after initial therapy
• Class III or IV angina, despite maximal medical therapy

Some patients with stable or asymptomatic IHD should be considered for referral to a cardiologist for possible coronary angiography, even after medical therapy has been optimized. The two general types of patients who should be considered for cardiology referral include the following:

1. Patients whose prior results from coronary angiography suggest a possible survival benefit from the use of coronary bypass surgery
2. Patients who have not yet had coronary angiography, but have Functional Class III to V angina or heart failure or whose non-invasive test results indicate a high risk for adverse outcomes

DISCUSSION

With only a few exceptions, coronary angiography is not clearly indicated in asymptomatic or mildly symptomatic patients with either known or suspected CAD, unless non-invasive testing reveals findings that suggest a high risk for adverse outcomes. The following list includes examples of non-invasive test results that indicate high and intermediate risk, for which cardiology referral for coronary angiography should be considered (adapted from ACC/AHA Guidelines for Coronary Angiography: Executive Summary and Recommendations, 1999).

High-Risk Findings on Non-Invasive Testing

• Severe resting LV dysfunction (LVEF<0.35)
• High-risk Duke treadmill score (score< -11)
• Severe exercise LV dysfunction (exercise LVEF<0.35)
• Stress-induced large perfusion defect (particularly if anterior)
• Stress-induced moderate-size multiple perfusion defects
• Large, fixed perfusion defect with LV dilatation or increased lung uptake (thallium 201)
• Stress-induced moderate-size perfusion defect with LV dilatation or increased lung uptake (thallium 201)
• Echocardiographic wall motion abnormality (involving >2 segments) developing at low dose of dobutamine (<10 mg/kg/min) or at a low heart rate (<120 bpm)
• Stress echocardiographic evidence of extensive ischemia

Intermediate-Risk

• Mild /moderate resting left ventricular dysfunction (LVEF = 0.35 to 0.49)
• Intermediate-risk treadmill score (–11 < score < 5)
• Stress-induced moderate perfusion defect without LV dilation or increased lung intake (thallium-201)
• Limited stress echocardiographic ischemia with a wall motionabnormality only at higher doses of dobutamine involving less than or equal to two segments

Stable, well-compensated IHD patients may present to the primary care provider with results from coronary angiography, suggesting the possible need for coronary bypass surgery. This decision most properly resides with a specialist in cardiovascular diseases, since this specialist is in the best position to discuss the relative risks and benefits of bypass surgery versus medical therapy or percutaneous revascularization. The current ACC/AHA Guidelines for Coronary Angiography (1999) suggest that patients with the following coronary anatomic findings should be considered for bypass surgery:

•  Significant left main coronary artery stenosis

•  Left main equivalent: significant (70%) stenosis of proximal left anterior desending coronary artery (LAD) and proximal left circumflex artery

•  Three-vessel disease (survival benefit is greater in patients with abnormal LV function; e.g., with an EF <0.50.)

•  Proximal LAD stenosis with 1- or 2-vessel disease

There is survival benefit for revascularization in patients with moderate LV dysfunction (ejection fraction 0.35 – 0.50) and angina (CASS, 1985).