Even if cholesterol tests and blood pressure readings don’t signal heart trouble, a CT scan could raise red flags.
In a new study published in the journal Radiology, researchers found that coronary CT angiography (CCTA) can help predict heart attack risk in patients who are suspected to have coronary artery disease, but don’t show signs of other risk factors, such as high cholesterol elevated blood pressure, or diabetes.
CCTA is the less invasive alternative to the coronary angiogram, in which doctors thread a catheter through an artery in the groin and into the heart in order to inject a dye that makes the heart’s vessels visible on X-rays. The procedure requires several hours of recovery in order to prevent abnormal bleeding, and often involves an overnight stay at the hospital. The CCTA requires no incisions; it simply relies on X-rays to take detailed pictures of the heart’s vessels.
The participants in the study came from an international cohort of 27,125 patients who underwent CCTA at 12 different centers. The researchers focused in on the population of 5,262 patients who received the scans even though they did not have the usual risk factors, but only a suspected risk of potential heart problems. These patients may be particularly unprepared for possible heart issues since they generally do not show any symptoms of heart disease, do not harbor any of the traditional risk factors for the condition, and therefore are not likely to be monitored closely for future problems. “The asymptomatic patients without modifiable risk factors, those are a unique population,” says study author Dr. Jonathon Leipsic, vice chairman of the research department of radiology at the University of British Columbia. “They do not meet current guidelines for performing cardiac CT. Most of those patients were scanned in Korea and other countries where scanning is popular despite the lack of scientific evidence. We felt that instead of excluding those patients, we might as well learn from their imaging.”
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And that lesson proved to be informative. After a two-year follow-up, 104 patients experienced a major adverse cardiovascular event. It turned out that the group had coronary artery disease that might have gone undetected and untreated because the participants did not possess the standard risk factors that would otherwise alerted them or their doctors to heart problems; some had symptoms, but they were not always typical of heart trouble. Over a quarter of the patients had plaque build-up in the arteries, and 12% had more serious obstructive disease in which over half of at least one coronary artery was blocked.
“The reason I wanted to do this analysis is that I really think that these are patients that are difficult for the cardiologists to assess,” says Leipsic. “Like a patient who is a 48-year-old woman with atypical symptoms, but doesn’t have diabetes or hypertension or anything that cardiologists can necessarily modify. I think what our analysis shows is that CT is a good first line test for these patients and they can really help identify those that are at no risk or at high risk.”
That seems like a good idea in theory, but in practice would mean that more relatively healthy people would be scanned and exposed to a small amount of radiation with the coronary CT in order to detect those who might be at risk of heart trouble. But Leipsic says that doctors’ understanding of risk factors for heart disease have changed, and therefore the ways in which they identify the most vulnerable populations should also be modified. “The typical risk factors used, or the descriptors of chest pain that used to hold true to help predict the likelihood of having significant coronary artery disease, don’t necessarily hold true in the modern era,” he says. “These rules were defined in the 70s, and patients are exposed to different things now. People used to be able to smoke on airplanes and right next to you in restaurants. It’s a very different cardiovascular world [now].”
But he agrees that more studies need to be done to compare the benefits of identifying more at-risk patients with the risks of exposing more people to the radiation from the scans.
“I do think that for symptomatic patients with suspected, but not confirmed coronary artery disease, CT is the single best first-line test,” he says. “It has it’s limitations and you need to interpret it accurately, and it needs to be done thoughtfully and with radiation dose reduction in mind, but with all those caveats, I think it is powerful. I think CT detects disease in a much more sensitive and specific way than other noninvasive tests.” And for those without any symptoms of heart problems, the test could potentially be a life-saver and help doctors to intervene with treatments or advise behavioral changes that could minimize the risk.