NEW YORK — Coronary calcium scanning followed by myocardial perfusion imaging looks like it may be an effective approach to screening for coronary disease, John J. Mahmarian, M.D., said at the annual meeting of the American Society of Nuclear Cardiology.
“Further investigation needs to focus on the complementary role of CT scanning [for coronary calcium] and SPECT [single-photon emission computed tomography] for more precisely defining patient risk and recommending who should receive aggressive, antiatherosclerotic treatments,” said Dr. Mahmarian, medical director of the nuclear cardiology laboratory at the Methodist Hospital, Houston.
Screening for coronary calcium by electron beam CT or by multislice CT is well suited for selected, asymptomatic people because it has a relatively low cost and because conventional risk factors are not foolproof for identifying asymptomatic people who have coronary disease, he said.
“About 25% of people with three, four, or five risk factors for coronary disease have very little coronary calcification, and about 25% of patients with very high calcium scores have zero or one risk factor,” Dr. Mahmarian noted. In addition, the results from several studies have shown that people with high coronary calcium scores have a markedly increased risk of having myocardial perfusion defects and significant coronary disease. Therefore, he said, screening for coronary calcium makes sense for people with an intermediate or high risk for coronary disease based on their risk factor profile.
Dr. Mahmarian proposed that people with an intermediate or high risk based on their risk factors who have a calcium score of less than 100 do not need additional, immediate testing but should be managed for risk factor reduction and treated with aspirin and a statin.
People with a calcium score of 100–399 should be placed on an aggressive, risk-factor reduction regimen and are potential candidates for further, noninvasive testing by myocardial perfusion imaging using SPECT. Whether myocardial perfusion imaging is used on people in this category or not should depend on the severity of their risk factors as well as their age and gender. These people should have follow-up screening for coronary calcium every 1–2 years. Dr. Mahmarian said that about 15% of people screened could be in this category.
Those with a calcium score of more than 400—about 10% of the screening population—should receive aggressive risk-factor management plus noninvasive testing by SPECT. People who show a large perfusion defect on myocardial perfusion imaging are candidates for coronary angiography. Those who are negative for a significant perfusion defect should be rescreened with SPECT annually, Dr. Mahmarian said.