The advances in cardiac imaging that have taken place in the last few years have provided amazing visualization of cardiac function in health and disease. Imaging has also enabled us to target areas of the heart for medical and surgical intervention.
The images are so slick that we have been known to e-mail them to our patients to show them how clever we are. I am told that they have been used to liven up cocktail parties. In a larger sense, however, few new concepts have emerged as a result of these imaging advances that physiologists and anatomists have not already elegantly described in the past.
We have been obsessed with the possibility that imaging of the heart and the coronary vessels would unlock the mysteries of acute coronary events and provide predictive information of subsequent myocardial infarction. The advances in computed tomography – first with the exercise electrocardiogram (with and without radiographic imaging), followed by coronary angiography, and most recently with CT coronary angiography – are only the most recent attempts to identify the culprit in this long-running quest for the triggers of acute coronary events.
And yet, the answer eludes us. Even when we were able to image the atherosclerotic plaque itself, we found that new events occurred in seemingly normal vessels. So it is not surprising that the ROMICAT II (Rule Out Myocardial Infarction II) study – the most recent study evaluating emergency department patients with acute chest pain using CT angiography – failed to provide any new insight into the diagnosis and prediction of the acute coronary syndrome. Compared with standard evaluation, CT angiography failed to show any clinical benefit other than shortening the average stay in the ED by 7.6 hours (which is unquestionably a quality benefit if your emergency department is anything like mine).
ROMICAT II did show that coronary events were rare in this highly selected patient population who were aged 40-74 years, had no history of coronary artery disease or ischemic electrocardiographic abnormalities, and had normal troponin assays. In the succeeding 28 days following emergency evaluation, there were no acute coronary events detected, and there were only eight adverse cardiac events observed.
Because of the unlikely occurrence of coronary events, these patients can best be dealt with in a nonemergency setting. Both CT angiography and standard testing led to further tests during the 28-day follow-up, including exercise echocardiograms (with or without nuclear imaging) and coronary angiography in roughly three-fourths of the patients. Revascularization was performed in 10% of the population.
So why are we even testing these patients and exposing them to all of the exigencies of ED and hospital admission? We are clearly not providing any service to them. At the same time, we are exposing them to increased radiation and the hazard of the testing procedures themselves. Some would say that the testing was driven by the risks of malpractice litigation. This study should provide some "cover" for that concern, which is undoubtedly real.
The continuing dependence on imaging technology to solve clinical problems has led to the numbing of our ability to perform cognitive processing of clinical data. Heart failure is no longer a clinical entity; it is an echocardiography image. The acute coronary syndrome is not a clinical syndrome, but rather an acquired image or blood test. Daily ward rounds have evolved into a hierarchical listing of the next imaging test to be performed on the patient in order to solve the clinical problem at hand. Consequently, the approach to the patient is no longer a quest to understand what is probable, but a search for the improbable.
A continuous barrage of publications in the medical and lay press has addressed the dollars wasted on imaging procedures, with seemingly little letup in the use of these technologies. Clearly, in the "zero-sum game" world of modern medicine, these costs will ultimately come out of physician’s income. Beyond that, we should realize that they add very little to the care of our patients and may actually add to their risks.
Dr. Goldstein, medical editor of Cardiology News, is a professor of medicine at Wayne State University and division head emeritus of cardiovascular medicine at Henry Ford Hospital, both in Detroit. He is on data safety monitoring committees for the National Institutes of Health and several pharmaceutical companies.