title: Dysregulation of coronary microvascular reactivity in asymptomatic patients with type 2 diabetes mellitus.
abstract: In diabetic patients, a number of studies have suggested an impairment of vascular reactivity in response to vasodilatory stimuli. The pattern of dysregulation at the coronary microcirculatory level, however, has not been clearly defined. Thus, it was the aim of this study to characterise coronary microvascular function non-invasively in a homogeneous group of asymptomatic type 2 diabetic patients. In 46 patients with type 2 diabetes, myocardial blood flow (MBF) was quantified at baseline, in response to cold pressor test (CPT) and during adenosine-mediated vasodilation using positron emission tomography and nitrogen-13 ammonia. None of the patients had been treated with insulin, and none had symptoms of cardiac disease. Decreased MBF during CPT, indicating microvascular dysregulation, was observed in 16 patients (CPT-), while 30 patients demonstrated increased MBF during CPT (CPT+). Response to CPT was mildly, but significantly correlated with response to adenosine ( r=0.44, P=0.0035). There was no difference in HbA1c, serum lipid levels or serum endothelial markers between the groups. Microvascular dysregulation in the CPT- group was associated with elevated baseline MBF ( P<0.0001), reduced baseline vascular resistance ( P=0.0026) and an abnormal increase in resistance during CPT ( P=0.0002). In conclusion, coronary microvascular dysregulation is present in approximately one-third of asymptomatic, non-insulin-treated type 2 diabetic patients. Elevated baseline blood flow and reduced microvascular resistance at rest are characteristics of this dysregulation. These data suggest a state of activation of endothelial-dependent vasodilation at baseline which appears to limit the flow response to stress conditions.
authors.affiliation: Nuklearmedizinische Klinik und Poliklinik der Technischen Universität München, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Momose
authors.forename: Claudia
authors.initials: C
authors.lastname: Abletshauser
authors.forename: Jodi
authors.initials: J
authors.lastname: Neverve
authors.forename: Stephan G
authors.initials: SG
authors.lastname: Nekolla
authors.forename: Oliver
authors.initials: O
authors.lastname: Schnell
authors.forename: Eberhard
authors.initials: E
authors.lastname: Standl
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.forename: Frank M
authors.initials: FM
authors.lastname: Bengel
mesh_terms: D000241:Adenosine; D001783:Blood Flow Velocity; D003080:Cold Temperature; D003326:Coronary Circulation; D003327:Coronary Disease / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003925:Diabetic Angiopathies / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006487:Hemostasis; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000000981:diagnostic imaging / Q000503:physiopathology; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed / Q000379:methods*
chemical_list: D000241:Adenosine