Dual-source CT excels in segment-by-segment diagnosis of coronary artery disease

The first substantive clinical trials of dual-source CT suggest it will deliver on a promise to improve the detection of coronary artery disease. A Dutch study published in the August 21 issue of the Journal of the American College of Cardiology found it is 95% sensitive and 95% specific on a per-segment basis for diagnosing significant stenoses.

Dual-source CT

Reliable high-speed coronary computed tomography in symptomatic patients

J Am Coll Cardio 2007;50:786-794

A segment-by-segment analysis, performed by Dr. Pim J. de Feyter and colleagues at the Thoraxcenter and Erasmus Medical Center in Rotterdam, the Netherlands, found that dual-source CT was 95% sensitive and 95% specific to the presence of 50% or greater stenosis. It was 99% sensitive and 87% specific on a per-patient basis. Lead author Dr. Annick Weustink evaluated 1489 coronary segments containing 220 significant stenoses in100 patients with atypical or typical angina pectoris or unstable coronary artery disease.

Coronary artery disease

Underestimation of extent of ischemia by gated SPECT myocardial perfusion imaging in patients with left main coronary artery disease

J Nuc Cardio 2007;14(4):521-528

Visual or quantitative readings of SPECT myocardial perfusion imaging will underestimate coronary artery disease in the left main artery, Dr. Daniel Berman, director of nuclear cardiology at Cedars Sinai Medical Center in Los Angeles, found in a study of 101 patients with known left main coronary artery disease. Using perfusion assessment alone, high-risk disease with moderate-to-severe defects involving more than 10% of the myocardium was identified in only 56% of patients during visual interpretation and 59% of patients during quantitative analysis. By combining both approaches and nonperfusion variables, especially transient ischemic dilation, 83% of patients were identified as high risk.

Incidental findings

Cardiac CT angiography after coronary bypass surgery: prevalence of incidental findings

AJR 2007;189(2):414-419

ECG-gated 16-slice CTA performed around five days after coronary artery bypass graft surgery identified unsuspected cardiac or other clinically significant findings in about one in five patients in this retrospective analysis of 259 postop cases. Dr. Jeffrey Mueller and colleagues noted significant findings in 51 patients soon after surgery. About 9% had a cardiac finding, such as ventricular pseudoaneurysm, ventricular perfusion deficit, or intracardiac thrombus. About 13% had a noncardiac finding, such as a pulmonary embolism, lung cancer, or pneumonia. At least one bypass graft was occluded in 6.6% of the patients. CTA performed a year after surgery showed seven patients with a potentially significant finding, including four patients with at least one graft occlusion.

Heart failure risk

Cardiac steatosis in diabetes mellitus. A 1H-magnetic resonance spectroscopy study

Circulation 2007; published online before print Aug. 13, 2007

Multidisciplinary research involving several Veterans' Administration and teaching hospitals in Dallas employed proton MR spectroscopy to demonstrate that impaired glucose tolerance and cardiac steatosis develop together. Both precede the onset of type 2 diabetes and left ventricular systolic dysfunction. The research team, led by Dr. Lidia S. Szczepaniak, Ph.D., at the University of Texas Southwestern Medical Center, established these conclusions based on MRS performed on 134 volunteers. Jonathan M. McGavock, Ph.D, was first author. Localized cardiac MRS help establish that the myocardial triglyceride content was 2.3 times higher in subjects with impaired glucose tolerance and 2.1 times higher in subjects with type 2 diabetes.

Myocardial viability

Prognostic value of myocardial viability detected by myocardial contrast echocardiography early after acute myocardial infarction

J Am Coll Cardio 2007;50(4):327-334

Previous studies have shown that myocardial echocardiography accurately predicts left ventricular recovery for patients after acute myocardial infarction. This trial, involving 99 stable patients who underwent an echo exam an average of seven days after infarction, indicates the procedure can predict adverse events after postinfarction thrombolysis. Of 95 patients available for follow-up, 86 underwent thrombolysis in the laboratory of Dr. Roxy Senior and colleagues at Northwick Park Institute of Medicare Research in Harrow, U.K. They found that residual myocardial viability, identified during the echo test, was an independent predictor of cardiac death (p = 0.01) and cardiac death or acute myocardial infarction (p = 0.02) in the 46-month follow-up period.

Coronary artery wall imaging

Delayed-enhancement cardiovascular magnetic resonance coronary artery wall imaging

J Am Coll Cardio 2007; 50: 441-447

A preliminary study of 14 patients with cardiovascular risk factors and six healthy volunteers suggests that delayed-enhancement cardiac MR coronary vessel wall imaging can assess the severity of coronary atherosclerosis. Lead author Dr. Susan B. Yeon worked with radiologists Dr. Melvin Clouse and Dr. Warren Manning at Beth Israel Deaconess Medical Center, Dr. David Maintz at the University of Muenster in Germany, and Dr. Rene Botnar at the Technical University of Munich to develop the protocol and study. She found a greater prevalence of strong delayed enhancement with MR in segments that produced persuasive evidence of disease during multislice CT angiography. Compared to quantitative coronary angiography, delayed enhancement was seen in eight of 15 segments with greater than 20% coronary artery stenosis diagnosed with QCA, but also in 12 of 80 segments without angiographically apparent coronary disease.

Left ventricular hypertrophy

Prognostic implications of stress Tc-99m tetrofosmin myocardial perfusion imaging in patients with left ventricular hypertrophy

J Nuc Cardio 2007; 14(4): 521-528

Dr. Abdou Elheny and colleagues at the University Hospital Rotterdam in the Netherlands found that stress technetium-99m tetrofosmin myocardial perfusion imaging helped assessed the risk of death for 177 patients with confirmed left ventricular hypertrophy. Multivariant analysis showed that along with male gender and hypercholesterolemia, an abnormal perfusion study was an independent predictor of death in the five years following imaging. The annual mortality rate was 1.4% in patients with normal perfusion, 3.2% in those with perfusion abnormalities in a single-vessel distribution, and 8% in those with multivessel distribution.