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29-01-2012 | Cardiology | Article

Pretest heart disease probability ‘should be considered’ before using CTA

Abstract

Free abstract

MedWire News: Pretest probability for coronary artery disease (CAD) and coronary calcium scoring should be considered before using computed tomography angiography (CTA) for excluding obstructive CAD, researchers say.

CTA is less effective in patients with a calcium score of 600 units or less and in patients with a high pre-test probability for obstructive CAD, report Joăo Lima (Johns Hopkins University, Baltimore, Maryland, USA) and colleagues in the Journal of the American College of Cardiology.

The Coronary Artery Evaluation Using 64-Row Multidetector Computed Tomography Angiography (CORE-64) study originally excluded patients with a calcium score of less than 600 Agastron units, a criterion that eliminated 89 of 405 patients (22%) from the analysis.

However, the current CORE-64 analysis included these patients, and in total, involved 371 patients who underwent CTA and cardiac catheterization for the detection of obstructive CAD (defined as ≥50% luminal stenosis by quantitative coronary angiography).

The analysis of patient-based quantitative CTA accuracy revealed an area under the receiver-operating characteristic curve (AUC) of 0.93. After excluding patients with known CAD, the AUC remained the same, but decreased to 0.81 in patients with a calcium score of 600 or less.

Although AUCs were similar among patients with intermediate and high pre-test probability for CAD and those with known CAD, at 0.93, 0.92, and 0.93, respectively, negative predictive values were significantly different, at 0.90, 0.83, and 0.50, respectively.

In addition, negative predictive values decreased from 0.93 for patients with a calcium score of less than 100 to 0.75 for those with a score of 100 or more (p=0.053).

"Our results demonstrate that pre-test probability for CAD and coronary calcium score, which are both predictive of disease prevalence, are important for the effectiveness of CTA to exclude or confirm the presence obstructive CAD in patients," write the authors.

They conclude: "In patients with clinical suspicion of CAD sufficient to consider cardiac catheterization, moderate or severe coronary calcification alone is highly predictive of obstructive CAD."

Editorialist Steven Nissen (Cleveland Clinic, Ohio, USA) writes: "The careful analysis provided by the current study will be valuable to practitioners considering how to optimally apply coronary CTA in routine clinical practice."

"These findings suggest that CTA, using current technology, probably should not be used for diagnostic purposes in patients with substantial coronary calcification."

MedWire (http://www.medwire-news.md/) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Piriya Mahendra

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