Better Strategies for Diagnostic Imaging Can Cut Unnecessary Treatment for CAD
Coronary artery disease (CAD) in patients with chest pain symptom occurs at a far lower prevalence than expected. Strategies involving noninvasive imaging have the potential to cut unnecessary and costly interventions by as much as 75%, according to preliminary findings from the EVINCI study presented to European trialists in Madrid, Spain, on June 26, 2012.
The EVINCI (Evaluation of Integrated Cardiac Imaging) study was designed by members of the European Society of Cardiology Working Group on Nuclear Cardiology and Cardiac CT. Danilo Neglia, MD, PhD, of Fondazione Toscano Gabriele Monasterio (Pisa, Italy), and colleagues enrolled 695 patients with chronic chest pain and high probability of CAD at 17 European institutions. Each participant underwent integrated noninvasive imaging followed by cardiac catheterization when appropriate to confirm the presence, extent, and functional relevance of CAD. Patients were followed for a maximum of 3 years. In addition, various noninvasive strategies were compared for their diagnostic accuracy, and costs and potential risks were monitored.
Although the average estimated probability of CAD in the study population was 60%, the actual prevalence of confirmed disease requiring revascularization was only 25%.
The results “show that a number of invasive coronary angiography procedures are unnecessary,” Dr. Neglia said in a press release. “In these patients, a noninvasive diagnostic imaging test can be performed, which would save money and be safer for patients.”
Because there are so many methods available for diagnosing CAD, it is important to study how to do so most efficiently, Dr. Neglia commented. While “the strengths and weaknesses of each technique” are known, he said, “there is no clue as to which approach is the most cost effective to solve the diagnostic issue and define proper treatment in the single patient.”
However, in a telephone interview with TCTMD, Robert S. Schwartz, MD, of the Minneapolis Heart Institute Foundation (Minneapolis, MN), said without seeing a breakdown of how imaging modalities were used, this study is “difficult to interpret.” He also stressed the need to know the trial’s false-positive rate, because the 25% CAD prevalence is “unacceptably high” even among high-risk populations.
“If one is going to look at a screening method for the general population, the prevalence of disease is less than 5% at any given point,” Dr. Schwartz said. “The problem is the performance of the test is prevalence dependent.” Until these details are understood, “the jury is out” on confirming EVINCI’s results, he observed.
One explanation may be that the trial was designed by a consortium partially focused on cardiac CT, Dr. Schwartz suggested. “[I]f in fact a number of these patients had CT, [then] that may explain the numbers.”
Despite his reservations about the study, Dr. Schwartz said he supports the use of CT in this patient population. “I think we are evolving to a more CT-based methodology at numerous centers now,” he commented. “The good news about that is that the patients that go to the cath lab belong in the cath lab, and there are patients who have CT done by good centers with good interpretation. There are no surprises in the cath lab anymore.”
A Timely Tool
The massive data set collected by EVINCI has been used to form an online resource, eduCAD (www.escardio.org/educad), meant to train cardiologists how to best utilize imaging tests in diagnosing CAD. Employing clinical cases from the trial, eduCAD asks users to choose the most appropriate strategy based on an initial description of the patient and stress ECG. The user can then compare their hypothetical imaging pathway, diagnosis, and treatment plan with the commission’s recommendations. Results of multiple noninvasive imaging tests and coronary angiography are available for each case.
“This will help young cardiologists . . . understand which imaging strategy could have been chosen in that specific patient to maximize efficacy in performing the final diagnosis and addressing the right treatment,” Dr. Neglia said. “Ultimately eduCAD should help cardiologists choose the most appropriate diagnostic test the first time round. This will reduce the use of unnecessary tests, save money, and provide a better experience for patients.”
Dr. Schwartz concurred. “When these programs are designed by good centers and people that are used to dealing with diagnostic problems and diagnostic technologies, it’s a good thing for standardizing practice and for standardizing the approach to these patients,” he said.
Going forward, it will be important to understand how to individually tailor imaging strategies, Dr. Schwartz concluded. “We just have to pay attention to the limitations and not apply [certain imaging modalities] to patient subsets where they are not as effective.”
Dr. Neglia and colleagues add that the digital and biological banks that were created as part of the study will be relevant not only for the final analysis of EVINCI but also for future studies and educational purposes.
Patients were aged 30 to 75 years, and 38% were female. Noninvasive imaging tests were chosen to assess both coronary anatomic abnormalities and their functional effects. In each patient, coronary anatomy was assessed using multislice CT. Radionuclide imaging (either SPECT or PET) was used to measure myocardial perfusion at rest and during stress. The effects of myocardial ischemia on ventricular function were assessed by either MRI or echocardiography during stress.
European Society of Cardiology. EVINCI results could lead to 75% reduction of invasive procedures for patients with suspected coronary artery disease [press release]. http://www.escardio.org/about/press/press-releases/pr-12/Pages/EVINCI-results.aspx. Published June, 26, 2012. Accessed June 28, 2012.
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- The press release contains no statement regarding conflicts of interest for Dr. Neglia.
- Dr. Schwartz reports no relevant conflicts of interest.