Magnetic Resonance Adenosine Perfusion Imaging as Gatekeeper of Invasive Coronary Intervention

Current guidelines for the diagnosis and management of patients with stable coronary artery disease (CAD) recommend - besides thorough history and physical examination - proper risk stratification prior to invasive therapy. The detection or exclusion of moderate to severe reversible myocardial ischemia is a crucial part of the work-up process which designates the patients to the high-risk group when ischemia is present. This is of special interest, as several observational studies have shown that the prognostic benefit from revascularization depends on the amount of myocardial ischemia. Moreover, patients without ischemia do not seem to benefit from revascularization over optimal medical therapy. This emphasizes the need for functional testing prior to therapeutic decisions.

Invasive coronary angiography still is considered to be the "gold-standard" for the diagnosis of CAD, though it exhibits several limitations and shortcomings. Multiple studies have documented the significant interobserver variability in the grading of coronary artery stenosis, as well as the frequent occurrence of under- and overestimation of hemodynamic relevance. One has to conclude that coronary angiography may provide anatomical information but is not the modality of choice concerning the detection of myocardial ischemia. Moreover, there is no study which has randomized patients with stable CAD to either catheterization or no catheterization yet, so there does not exist high-quality evidence which would support the performance of a diagnostic coronary angiography in the majority of cases of stable CAD. This is of special interest, as there is a reported frequency of complications due to diagnostic coronary angiography of about 1.5%. Nevertheless, coronary angiography remains the most often performed diagnostic test in this setting, with more than one-half of elective percutaneous coronary interventions (PCI) done without previous stress-testing.

Adenosine perfusion cardiac magnetic resonance imaging (CMR) is an imaging modality which provides anatomical and functional information in one single examination. With its ability to reliably detect reversible myocardial ischemia, it plays an increasing role in the diagnosis and risk stratification of patients with suspected or known CAD. Though CMR therefore is highly recommended in the diagnostic work-up in the setting of stable CAD, no study exists which would have evaluated a CMR driven approach in patient management with regard to the occurrence of major cardiac events, quality of life and safety endpoints.

Objective of our study is to show that a CMR based conservative or invasive management of patients with suspected or known CAD is not inferior with regard to major cardiac endpoints and quality of life in comparison to a - more conventional - coronary angiography based approach. The investigators assume that a significant number of diagnostic coronary angiographies and PCIs thus could be spared without decrease in patient safety and comfort.