Reed Miller

July 26, 2012

July 25, 2012 (Baltimore, Maryland) — The CONFIRM registry shows that among patients who show only nonobstructive disease on a coronary computed tomography angiogram (CCTA), those with acute symptoms have worse outcomes than those with chronic symptoms [1].

"Any disease found in patients with acute symptoms is actually significant in that people who had acute symptoms actually had more major adverse events with the same degree of disease," Dr Kavitha Chinnaiyan (William Beaumont Hospital, Royal Oak, MI) told heartwire . Chinnaiyan presented results from a 9678-patient study derived from CONFIRM at the Society of Cardiovascular Computed Tomography (SCCT) 2012 Annual Scientific Meeting. "Having even mild disease with acute symptoms means the physiology is different than having chronic stable disease."

"We're using [CCTA] for rapid triage, but then we really don't know what happens to these patients," she said. "If you look at the ER studies, it's unclear what happens to them. Do they go back to a cardiologist? Are they referred? How are they treated? We don't know that."

As shown in ROMICAT II and ACRIN, CCTA is a safe test for screening patients with chest pain in the emergency department. "That's how it's being used in the real world. If you come in with acute chest pain, you get a CT, and if you don't have obstructive disease, you go home," Chinnaiyan said. "[The study results] show that, yes, [CCTA] is a great tool to diagnosis coronary disease in the emergency room, but we need to be more cognizant of the fact that for people who have any disease, even mild disease, there's an opportunity for aggressive secondary prevention, which we really hadn't emphasized with any of the prior studies."

In the study, Chinnaiyan and colleagues analyzed 27 125 consecutive patients in CONFIRM to identify 9678 symptomatic patients with no prior record of coronary disease. Of these, 7204 with chronic symptoms of possible coronary disease presented to a physician in an outpatient setting, while 2467 with acute symptoms presented at an emergency department.

Multivariate analysis shows that the strongest predictors of major adverse events over an average follow-up of 2.2 years in patients with obstructive disease were the traditional risk factors such as family history, male gender, smoking, etc. But among the patients with nonobstructive disease, the most important risk factor was acute presentation of symptoms. Among the patients with nonobstructive disease, those who presented with acute symptoms had a worse rate of mortality than those with obstructive disease (3.5% vs 1%, p<0.001) and a worse overall major adverse-event rate (4.2% vs 2.1%, p=0.002). Among patients with obstructive disease, those with acute symptoms had a higher mortality (5.6% vs 2.4%, p=0.001) than those with chronic symptoms, but the overall adverse-event rates were similar (11% vs 8.6%, p=0.16).

Future studies of patients in the CONFIRM registry will examine plaque characteristics that might explain these differences between the acute and nonacute patients, Chinnaiyan said. Her group is also hoping to understand what happens to acute coronary syndrome patients after they are discharged from the hospital. They are conducting a prospective study in Michigan, separate from CONFIRM, using claims data to look at the long-term outcomes in these patients. "How many of these patients are actually referred to a cardiologist for aggressive secondary prevention, and over time, does that make a difference between those who are referred and those who are not referred?"

Chinnaiyan also plans to study, retrospectively, whether aggressively treating patients with nonobstructive disease shown on CCTA actually prevents future adverse events and/or saves resources.

She emphasized that while many previous studies of CCTA cost-effectiveness have focused on the Medicare population, her group is focused on younger patients. "For the Medicare population, it's not really clear if they should be getting a CT, because they have a higher burden of disease, so of course they're going to use more resources. But these patients, the younger ones, are getting CT in the real world. Are we making a difference in their outcomes?"

Chinnaiyan has no relationships to disclose.

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