Monday, August 4, 2008

DCRI researchers propose framework for studying CV imaging technologies
by Maggie De Pano

Imaging technologies such as CT scans and MRIs can potentially improve the management of patients with heart disease. However, the Centers for Medicare and Medicaid and other payers have scrutinized the high cost of diagnostic imaging. They have also called for high quality evidence, in the form of well-designed clinical trials, demonstrating that cardiovascular imaging does lead to meaningful changes in patient outcomes.

In an article published July 2008 in the American Journal of Cardiology, researchers from the Duke Clinical Research Institute (DCRI) proposed a set of design characteristics that could maximize the clinical relevance of cardiovascular imaging trials and potentially help payers make reimbursement decisions. They used Computed Tomography Angiography (CTA), an imaging technology that uses x-rays to visualize blood flow throughout the body, as a model for their design.

The proposed framework focused on site selection, patient selection and trial outcomes.

The researchers recommended executing trials in multiple sites across wide geographic boundaries and in a variety of settings, as this reflects real-world variations in health care professionals’ ability to acquire images and interpret results, as well as in the characteristics of patient populations. In contrast, current evidence for CTA is derived largely from single-center trials.

Investigators should also choose clinically relevant patient populations, the authors noted. CTA is potentially useful in diagnosing acute chest pain, so selecting patients presenting with chest pain but with no previous diagnoses of coronary artery disease (CAD), positive cardiac biomarkers indicative of CAD, or ECG evidence of ischemia (an obstruction of blood flow to the heart) would be ideal. Current cardiovascular imaging studies often select patients who already have a high risk for CAD, as determined by cardiac catheterization or some other diagnostic procedure.

Additionally, the authors proposed a set of study outcomes that researchers should use to measure the clinical relevance of a new imaging technology. These outcomes include physician confidence in the technology’s quality, the frequency with which patients would have to undergo diagnostic imaging again due to a previous test’s inability to eliminate the possibility of CAD, radiation exposure, complications of testing, major adverse cardiac events, costs, and expected patient enrollment.

Cardiovascular imaging has become a cornerstone of modern medical care, the authors noted, but patient selection, trial design, quality and consistency, costs, and meaningful clinical outcomes should always be considered when assessing the operating characteristics of CTA and cardiovascular imaging in general.

The research study design for cardiovascular imaging was proposed by the DCRI’s Bimal R. Shah, MD, MBA; Manesh R. Patel, MD; Eric Peterson, MD, MPH; and Pamela S. Douglas, MD.