Appropriateness of diagnostic coronary angiography as a measure of cardiac ischemia testing in non-emergency patients - a retrospective cross-sectional analysis.

Background: Adequate application of guidelines concerning non-invasive ischemia testing (NIIT) could avoid inappropriate invasive testing in non-emergency situations. Hardly any data exists regarding frequency and appropriateness of diagnostic coronary angiography (CA). The aim of this study was to evaluate the proportion and predictors of patients without NIIT prior to elective purely diagnostic CA without therapeutic intervention.

Methods: Retrospective cross-sectional analysis of insurance claims data from 2012 and 2013. Patients <18 years, acute cardiac ischemia and emergency procedures and patients insured in a managed care model were excluded from analysis. The proportion of patients with NIIT procedures (stress-ECG, transthoracic echocardiography, stress echocardiography, scintigraphy, computer tomography, heart MRI) undertaken within two months before diagnostic CA was assessed. Multiple logistic regression analysis was applied to investigate independent determinants for receiving NIIT.

Findings: 2714 patients were included for analysis. 37.5% (1018) did not receive any NIIT before CA. When high risk patients (patients having received therapeutic cardiac intervention within one month after or 18 months prior to diagnostic CA, n = 766) were excluded 34.3% (669) did not receive NIIT before CA. High risk status as well as >6 chronic comorbidities were independently associated with a lower proportion of NIIT (p<0.0001, OR 0.607 and p = 0.0041, OR 0.648), when additionally controlled for age, sex, language area, insurance coverage, inpatient treatment, cardiovascular medication and lower number of chronic comorbidities. Age (p<0.05, OR 1.009) and intake of oral antiplatelet therapy (p<0.0001, OR 1.914) were independently associated with a higher proportion of NIIT when controlled for the mentioned cofactors.

Conclusions: Our data show that despite the existence of guidelines a substantial overuse of a potentially harmful and inappropriate diagnostic intervention is performed suggesting the need for improvement of diagnostic pathways prior to invasive testing.