Noninvasive study of coronary microcirculation response to a cold pressor test

Background The aims of this study were to noninvasively (i) assess the coronary microcirculation changes in response to a cold pressor test ( CPT ) in control subjects, nondiabetic obese patients and patients with type 2 diabetes and (ii) investigate the response of the coronary microcirculation in patients with diabetes according to the presence or the absence of silent myocardial ischaemia ( SMI ), asymptomatic coronary stenosis ( CS ) and left ventricle hypertrophy ( LVH ). Methods The mean left anterior descending coronary flow velocity (m CFV ) was measured using transthoracic Doppler before and after a CPT in 16 control subjects, 11 obese and 66 asymptomatic diabetic patients with a high cardiovascular risk. Patients with diabetes were screened for SMI using stress myocardial scintigraphy and/or echocardiography. A coronary angiography was performed in those with SMI . Results At baseline, pressure–rate product ( PRP ) was correlated with mCFV ( r  = 0·23; P  < 0·05) and left ventricle mass ( r  = 0·26; P  < 0·05) in the whole population. Changes in PRP and mCFV during CPT were correlated with controls ( r  = 0·58, P  < 0·05), obese ( r  = 0·75, P  < 0·01) and diabetic patients without CS ( r  = 0·56, P  < 0·0001) or without LVH ( r  = 0·63, P  < 0·05) but not in diabetic patients with CS or with LVH . In patients with diabetes, SMI was associated with mCFV changes, independent of other parameters ( P  < 0·05). Conclusion Transthoracic coronary Doppler allows noninvasive study of changes in the coronary microcirculation during CPT . In asymptomatic patients with type 2 diabetes, this method showed that SMI was associated with mCFV changes during CPT and the presence of CS or LVH was associated with a mismatch between coronary microcirculation and myocardial oxygen demand.