Non-invasive diagnostics in case of suspected coronary artery disease assessed by IQWiG in Germany

The Institute for Quality and Efficiency in Health Care (IQWiG) investigated the extent to which evidence is available for the benefit and harm of non-invasive computed tomography angiography (CTA) and stress diagnostics using magnetic resonance imaging (MRI) in people with suspected coronary heart disease (CAD) using evidence mapping.

CAD is the most common cause of adult death in Germany in both men and women: deposits in the coronary arteries (arteriosclerosis) lead to narrowing of the vessels (stenosis) and thus to reduced blood flow to the heart muscle (myocardial ischemia). Typical symptoms are chest pain and tightness with shortness of breath (angina pectoris). Chronic CAD can also present with little or no symptoms other than shortness of breath. Therefore, an accurate diagnosis is essential for the correct care of patients with CAD.

Various imaging methods can be used to detect chronic CAD. In addition to invasive coronary angiography (ICA) using a left heart catheter, some non-invasive methods such as CTA or stress diagnostics using MRI can be used. The ICA and the CTA are morphological procedures and detect stenoses directly, but do not necessarily indicate ischemia. The CTA is currently the only non-invasive morphological procedure available for CAD diagnosis. Functional methods such as non-invasive stress MRI diagnostics, on the other hand, examine the consequences of stenoses for the blood flow to the heart muscle: stress MRI diagnostics test how the heart works under stimulated stress.

A focused search for systematic overviews was carried out in the MEDLINE database as well as on the websites of the National Institute for Health and Care Excellence (NICE) and the Agency for Healthcare Research and Quality (AHRQ). The search was limited to the publication date from 2015. Also, an oriented search was carried out according to evidence-based guidelines.

Through the focused research, 24 systematic overviews were identified as relevant for the question of evidence mapping. Of these, nine were selected for the presentation of the aggregated results.

Results:

• Three systematic reviews based on RCTs showed that myocardial infarctions after a CTA-based diagnostic - compared to the respective standard care (non-invasive functional procedure as well as undefined standard care) - occurred statistically significantly less frequently. Also, it was demonstrated in 1 systematic overview that, as a result of a CTA - compared to functional methods - an ICA had to be carried out statistically significantly more frequently. For MRI, a systematic overview showed that - compared to standard care - statistically significantly fewer ICAs were performed after this diagnostic procedure. No effect on all-cause mortality was shown for either CTA or MRI. There was insufficient data for the MRI for the outcomes "all-cause mortality" and "myocardial infarction"
• In the systematic overviews based on studies on diagnostic quality, sensitivities of 90% and more were found for the CTA as an index test. The specificities determined were 78% and 79% compared to the ICA and from 39% to 53% compared to the invasive fractional flow reserve (FFR) as a reference test
• Sensitivities of 82% to 91% and specificities of 74% to 80% were shown for the stress MRI as an index test compared to the ICA as a reference test. Compared to the invasive FFR as a reference test, the sensitivities ranged from 87% to 90%; the specificities ranged from 85% to 94% and were therefore sometimes higher than the sensitivities
• The three selected evidence-based guidelines consistently recommend non-invasive procedures as the first-line test for CAD diagnostic.

The IQWiG summarized that there is significant evidence on the benefits and harm of non-invasive CTA and stress MRI diagnostics in people suspected of having CAD. Therefore, a benefit assessment of one of the two or both methods would be possible. Above all, the results of the systematic overviews based on RCTs, in which effects of CTA on patient-relevant outcomes were shown, suggest that a benefit assessment could make a statement about the benefits and harm of the interventions.

The present report was prepared in the form of a working paper as part of the general contract. The Federal Joint Committee (G-BA) granted this to IQWiG in December 2004 to strengthen the institute's scientific independence. This enables IQWiG to address topics and work on them scientifically independently. In contrast to other forms of report, there are no deadlines for the publication of working papers.

The working paper in German can be found here.

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