Zero Coronary Calcium a ‘Gatekeeper’ Screen in Acute Chest Pain?
August 07, 2017
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WASHINGTON, DC — A large, single-center, retrospective study of patients who presented to the emergency department with acute chest pain and low- to intermediate-risk of acute coronary syndrome (ACS) showed that a coronary artery calcium (CAC) score of zero was highly predictive of not having obstructive coronary artery disease (CAD).
In symptomatic patients with low- to medium-risk of ACS, just over half had a CAC of zero, and of these, only 0.7% had obstructive CAD (>50% stenosis).
However, the rate of obstructive CAD was doubled in smokers and patients with type 2 diabetes.
But experts differed about whether these findings mean that a CAC of zero could be used as a “gatekeeper” to rule out ACS in these types of patients.
“CAC has a very high negative predictive value [and] can be used for a screening test” in low- to intermediate-risk patients with acute chest pain in the ER,” Dr Gowtham R Grandhi (Baptist Health South Florida, Miami) reported, in an oral session at the Society of Cardiovascular Computed Tomography (SCCT) 2017 Annual Scientific Meeting.
But “do the findings lead you to use CAC alone when CAC is zero?” session comoderator Dr Daniele Andreini (Centro Cardiologico Monzino, Milan, Italy) wanted to know.
“This could be used [alone], but we need more studies,” Grandhi replied.
In an email to theheart.org | Medscape Cardiology, senior author Dr Khurram Nasir (Baptist Health South Florida, Miami) said, “I see a clear value of absence of CAC acting as a gatekeeper for more advanced testing, adding value to managing the majority of the low-risk patients with [acute chest pain] in the emergency department.”
The risk of having an acute event or missing an obstructive disease with a CAC of zero is lower than a normal nuclear stress myocardial perfusion imaging test or stress echocardiography, which is routinely employed in a majority of hospitals in the country, Nasir said.
But he agreed that for smokers and patients with type 2 diabetes, “caution can be applied, [since the] risk of obstructive disease with CAC=0 is slightly above the accepted threshold of 1%.”
The two session comoderators, however, were not convinced that low-/intermediate-risk patients with CAC of zero could be discharged safely.
The overall rate of obstructive CAD was very low, but it was not zero, Andreini stressed to theheart.org | Medscape Cardiology. “We are speaking about safe discharge of patients after just [a coronary] calcium score,” he said. “I think it’s not enough.”
Similarly, comoderator Dr Mona Bhatia (Fortis Escorts Heart Institute, New Delhi, India) said that in India, most patients with acute coronary disease are younger than 45, before the age when coronary calcium begins to develop.
“If a patient comes with any kind of chest pain or any kind of symptoms or is at high risk, then just a coronary calcium is really not enough, in India,” she said, “because a lot of [patients] have soft plaques that are not going to show up on the calcium score.