Finding Gatekeeper to Cardiac Catheterization Laboratory
Finding Gatekeeper to Cardiac Catheterization Laboratory
Until recently, the prognostic value of SPECT-MPI was unsurpassed by other noninvasive tests. In a landmark study of 7,376 patients with normal exercise or adenosine SPECT-MPI from >10 years ago, the cardiac event rate was only 0.6% per year. This was linear over time for individuals without known CAD, underpinning the concept of the 18- to 24-month "warranty period" of a normal scan. These data extend to other methods of stress testing (SE, cardiac magnetic resonance, and positron emission tomography), with the literature supporting the prognostic importance not only of functional capacity, but also of the results of imaging.
The prognostic utility of CCTA has also been extensively studied. In the CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes International Multicenter) study, increasing extent, severity, and location of CAD predicted adverse outcomes. CCTA may identify very low-risk individuals—incremental to clinical scoring systems and CAD risk factors—and improves prediction, discrimination, and reclassification of these individuals as higher risk in the presence of CAD. Conversely, a large evidence base supports the benign outcome of patients without evidence of CAD by CCTA, with annualized event rates of 0.01% to 0.24%. Similar data have been obtained in patients undergoing CCTA for the evaluation of possible acute coronary syndrome (ACS). These data highlight the importance of the NPV by CCTA, not only to rule out obstructive CAD, but also to effectively rule out future adverse events with a long-term (≥5-year) "warranty period." CCTA's accuracy for the exclusion of CAD allows ICA to be restricted to patients with CT evidence of CAD.
Whereas the assessment of decision making after the results of functional testing suggests that it is rarely on the basis of risk, this problem may be more marked with CCTA. In a comparative analysis of outcomes after CT and stress testing in a large Medicare population, the provision of anatomic data was associated with an increased likelihood of subsequent cardiac catheterization, percutaneous coronary intervention, and coronary artery bypass graft surgery with CCTA compared with SPECT, and consequently with higher costs. CCTA use was associated with a lower likelihood of hospitalization for acute MI (0.19% vs. 0.43%; adjusted OR: 0.60; 95% CI: 0.37 to 0.98; p = 0.04), but no difference in overall mortality.
Relative Prognostic Utility of CCTA and Functional Testing
Until recently, the prognostic value of SPECT-MPI was unsurpassed by other noninvasive tests. In a landmark study of 7,376 patients with normal exercise or adenosine SPECT-MPI from >10 years ago, the cardiac event rate was only 0.6% per year. This was linear over time for individuals without known CAD, underpinning the concept of the 18- to 24-month "warranty period" of a normal scan. These data extend to other methods of stress testing (SE, cardiac magnetic resonance, and positron emission tomography), with the literature supporting the prognostic importance not only of functional capacity, but also of the results of imaging.
The prognostic utility of CCTA has also been extensively studied. In the CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes International Multicenter) study, increasing extent, severity, and location of CAD predicted adverse outcomes. CCTA may identify very low-risk individuals—incremental to clinical scoring systems and CAD risk factors—and improves prediction, discrimination, and reclassification of these individuals as higher risk in the presence of CAD. Conversely, a large evidence base supports the benign outcome of patients without evidence of CAD by CCTA, with annualized event rates of 0.01% to 0.24%. Similar data have been obtained in patients undergoing CCTA for the evaluation of possible acute coronary syndrome (ACS). These data highlight the importance of the NPV by CCTA, not only to rule out obstructive CAD, but also to effectively rule out future adverse events with a long-term (≥5-year) "warranty period." CCTA's accuracy for the exclusion of CAD allows ICA to be restricted to patients with CT evidence of CAD.
Whereas the assessment of decision making after the results of functional testing suggests that it is rarely on the basis of risk, this problem may be more marked with CCTA. In a comparative analysis of outcomes after CT and stress testing in a large Medicare population, the provision of anatomic data was associated with an increased likelihood of subsequent cardiac catheterization, percutaneous coronary intervention, and coronary artery bypass graft surgery with CCTA compared with SPECT, and consequently with higher costs. CCTA use was associated with a lower likelihood of hospitalization for acute MI (0.19% vs. 0.43%; adjusted OR: 0.60; 95% CI: 0.37 to 0.98; p = 0.04), but no difference in overall mortality.
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