Marlene Busko

July 14, 2014

SAN DIEGO, CA — The 2013 American College of Cardiology (ACC) and American Heart Association (AHA) guidelines for managing cholesterol improve on previous guidelines because they are more likely to recommend statins for patients who actually have coronary obstructions that are detected by computed tomography (CT) angiography, researchers report[1].

In an analysis of data from the Rule Out Myocardial Infarction With Computer-Assisted Tomography (ROMICAT I) study of patients who presented with acute chest pain, more patients were deemed to require statin therapy when applying the new guidelines as opposed to the 2004 National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) guidelines—which was not surprising, based on other analyses.

However, what was "remarkable" was that the CT angiography findings showed that "essentially . . . the new guidelines are identifying more candidates for statin therapy who truly have atherosclerosis," Dr Amit Pursnani (Massachusetts General Hospital, Boson, MA) said in an oral presentation here at the Society of Cardiovascular Computed Tomography 2014 Annual Scientific Meeting . These findings may help mitigate concerns regarding the overprescribing of statins, he added.

Do Too Many People Now Qualify for Statins?

The 2004 NCEP ATP III lipid management guidelines are primarily based on LDL thresholds and the Framingham risk score, whereas the 2013 ACC/AHA guidelines are primarily based on the absolute risk of CVD that was determined in a pooled cohort of patients aged 40 to 75, with less reliance on LDL-cholesterol levels, Pursnani noted.

With this paradigm shift in the primary prevention of cardiovascular disease, there have been reports that the guidelines overestimate risk and may result in an overprescription of statin therapy, he continued.

The researchers sought to compare the two guidelines for statin eligibility to see whether the newer guidelines were better aligned with the actual presence of coronary artery disease (CAD) detected by coronary CT angiography.

They analyzed data from ROMICAT I, which enrolled 368 patients with low to intermediate risk of CVD who presented to the emergency department with acute chest pain suggestive of acute coronary syndrome.

The current study excluded ROMICAT I participants who actually had a clinical acute coronary syndrome or were not 40 to 75 years old, which left 252 participants, including 63 participants who were already taking statins.

The researchers determined which patients would be eligible for statin therapy according to the two guidelines.

They also determined the presence and severity of CAD based on coronary CT-angiography findings, where obstructive CAD was defined as a stenosis >50%.

The patients had a mean age of 53.9 years, and 43% were female. A total of 27% were smokers, and 41% were hypertensive; their average LDL cholesterol was 116 mg/dL.

Compared with the 2004 guidelines, the 2013 guidelines for the management of blood cholesterol identified more candidates for statin therapy: 106 of 252 patients vs 51 of 252 patients (p<0.0001).

Moreover, the relative risk of being eligible for statin therapy with the new guidelines (compared with eligibility with the prior guidelines) was greatest in patients with obstructive CAD.

The 121 patients without any coronary obstruction had a 1.65-fold higher likelihood of being eligible for statins with the new guidelines compared with the old guidelines.

The 95 patients with nonobstructive CAD had a 2.10-fold higher likelihood of being eligible for statins with the new guidelines compared with the old guidelines.

Last, the 36 patients with obstructive CAD had a 3.42-fold higher likelihood of being eligible for statins with the new guidelines compared with the old guidelines

More patients who have CAD are being "upgraded" to statin therapy with the new vs old guidelines, Dr. Pursnani observed.

However, "what's still impressive is that there's still roughly 20% of subjects with obstructive CAD . . . and roughly 40% of patients with nonobstructive CAD who are still not identified as candidates for statin therapy," he added.

He acknowledged that this was not a true primary-prevention study, since the patients all had atypical chest pain. "However, once acute coronary syndrome is ruled out in these subjects [as was done in his study], they fall under the rules of primary prevention," he said.

In reply to a question from a member of the audience, Pursnani said that they did not look at coronary calcium scores vs coronary CT angiography findings, although they plan to do this in further research.

"This is an interesting study because it shows that the information that you get from cardiac CT aligns well with what the [new ACC/AHA] guidelines say, as far as [recommending] statin therapy," even though the guidelines are controversial, session moderator Dr Mohamed Marwan (University of Erlangen, Germany) commented to heartwire .

Pursnani had no disclosures. Marwan receives honoraria from Edwards Lifesciences and Siemens Healthcare.

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