Echo wall motion exams predict risk of cardiovascular death.

Despite heated interest in cardiac CT, echocardiography continues to anchor the diagnosis and evaluation of coronary artery disease for most clinical practices. Echo possesses prognostic as well as diagnostic power, as demonstrated in a large Weill Cornell Medical College study. It found strong correlations between wall motion abnormalities detected during echocardiography and risk for cardiovascular death. On the cardiac CT front, more research investigating its clinical utility and radiation exposure was reported.

Wall motion abnormalities

Prevalence and prognostic significance of wall-motion abnormalities in adults without clinically recognized cardiovascular disease: The Strong Heart Study

Circulation 2007;116:143-150

Weill Cornell Medical College cardiologists, including Dr. Silvana Cicala and Dr. Richard B. Devereux examined 2864 subjects who were without overt areas of cardiovascular disease. Echocardiography of these subjects found that adults with left ventricular wall motion abnormalities have a 2.4 to 3.4-times higher risk of cardiovascular morbidity and mortality, independent of established risk factors, than adults with normal wall motion. The echocardiographic assessments found that 5% of patients had focal hypokinesia and 1.5% had wall motion abnormalities. Follow-up performed eight years after imaging linked segmental wall motion abnormalities with a 2.5 times higher risk of myocardial infarction, stroke, coronary artery disease, and heart failure and a 2.6-fold higher risk of cardiovascular death than normal subjects. Patients with global wall motion abnormalities were found to have a 2.4-fold higher risk of cardiovascular events and a 3.4-fold higher risk of cardiovascular death.

Obesity and radiation dose

Obesity is a major determinant of radiation dose in patients undergoing pulmonary vein isolation for atrial fibrillation

J Am Coll Cariol 2007;50:234-242

Researchers at the University Hospital Gasthuisberg in Leuven, Belgium, found that obese patients receive more than twice the effective radiation dose than patients of average weight during fluoroscopy-guided atrial fibrillation ablation. Cardiologist Dr. Joris Ector and colleagues calculated the effective radiation dose and lifetime attributable cancer risk from dose-area product (DAP) measures acquired from 85 patients undergoing AF ablation. The median DAP for all patients was 119.6 Gy per cm² during the four-hour procedures. A mean DAP value of 58±40 Gy per cm² was recorded for patients carrying an unremarkable amount of weight. Overweight patients had a mean DAP value of 110±43 gy per cm², and obese patients had a mean DAP value of 184±79 Gy per cm². The effective radiation doses for AF ablation for the three increasingly heavier body types were 15.2 mSv, 26.7 mSv, and 39 mSv, respectively. They correspond to a mean attributable lifetime risk of all-cancer mortality of 0.060%, 0.100% and 0.149%, respectively.

Coronary artery disease

Significant coronary artery stenosis: comparison on per-patient and per-vessel or per-segment basis on 64-section CT angiography

Radiology 2007;244:112-120

Dr. Christopher Herzog and colleagues in the radiology department at the Medical University of South Carolina reported mixed results for the accuracy of 64-slice CTA for diagnosing coronary artery disease. Unlike many previous studies, no segment or vessel in Herzog's trial was excluded because of impaired image quality. Consequently, the trial setting probably more accurately reflected the real-world application of 64-slice CTA than many prior studies. The approach was 89% accurate on a per-patient basis for diagnosis of greater than 50% coronary artery stenosis, but Herzog concluded that limited spatial resolution still stands in the way of 64-slice CTA's use for evaluations on per-segment or per-vessel bases. All CT coronary studies performed on 55 patients scheduled for x-ray coronary angiography were deemed diagnostic. About 92% of the 825 coronary artery segments visualized on conventional angiograms were visualized with CTA. Among the 63 problem segments, motion artifacts obscured anatomy in 19 segments, misregistration compromised image quality in 10 segments, and vessel diameters of less than 1.5 mm were a problem for 19 segments. Though the correlation between CTA and x-ray angiography was deemed good for grading stenosis, CTA incorrectly graded 56% of all stenoses, mainly because of its tendency to underestimate severity. Nine stenoses of 50% or greater were missed with CTA because of motion artifacts and other quality problems.

Radiation exposure

Pediatric cardiac-gated CT angiography: assessment of radiation dose

AJR 2007;189:12-18

Researchers from the McGovern-Davison Children's Health Center and Duke University Medical Center, both in Durham, NC, and Stanford University Medical Center in California completed an organ-by-organ evaluation of the radiation doses imparted on a typical five-year-old child during a cardiac-gated CT angiography. Dr. Caroline L. Hollingsworth and colleagues learned from procedures performed on an anthropomorphic phantom that the radiation doses varied greatly depending on imaging parameters. Effective doses can be as high as 28.4 mSv. Recorded organ doses included the following: breast (3.5 to 12.6 cGy), lung (3.3 to 21.1 cGy), and bone marrow (1.7 to 7.6 cGy).

Healthcare costs

Cost implications of initial computed tomography angiography as opposed to catheterization in patients with mildly abnormal or equivocal myocardial perfusion scans

JCCT 2007;1(1):21-26

In the inaugural issue of the

Journal of Cardiovascular Computed Tomography

, Dr. Jason H. Cole and colleagues at the University of South Alabama in Mobile tabulated the relatively lower costs of 64-slice coronary CTA compared with cardiac catheterization for patients with mildly abnormal or equivocal myocardial perfusion imaging. At the discretion of the treating physician, 206 patients underwent multislice CTA instead of catheterization. Results were graded as "no evident coronary artery disease," "nonobstructive CAD," or "potentially obstructive CAD." Based on reimbursement experience, selective catheterization saved $1454 per patient. Using MSCTA for this role remained cost-effective until catheterization was deemed necessary for more than 82% of the patients.

Chest pain

Usefulness of multislice spiral computed tomography coronary angiography in patients with acute chest pain in the emergency department

JCCT 2007;1(1):21-26

A study of 98 patients by Dr. Steffen Huber and radiological colleagues at the Texas Heart Institute in Houston suggests that 16-slice CT angiography helps assess patients with acute chest pain in the emergency room. It found that the 29% of patients with nondiagnostic mean image quality were significantly heavier and had higher heart rates than patients with diagnostic meant image quality.