Coronary microvascular dysfunction in patients with chest pain and unobstructed coronary arteries: Influence of systemic inflammation, plaque burden and morphology

Abstract

Aims: The aetiology of chest pain symptoms in the context of normal coronary arteries is not understood. A significant proportion have coronary microvascular dysfunction. This study assessed whether the presence of typical anginal symptoms were related to reduced global or regional myocardial blood flow flow reserve (MBFR), and whether this relationship was dependent upon gender, plaque measures or elevated markers of systemic inflammation (hs-CRP and endothelin-1). Methods: Patients undergoing CT coronary angiography (CTCA) for the investigation of ischaemic chest pain and found to have unobstructed coronary arteries (<50% stenosis), were recruited. MBFR was assessed using vasodilator myocardial contrast echocardiography. Patients symptoms were categorised into typical anginal pain (TAP) or nonanginal pain (NAP). Results: 183 patients, mean(SD) age 59.8(9.6) years (53% male) were recruited. Coronary artery plaque was present in 113(62%). Mean MBFR was 2.20(0.52), 38.3% MBFR<2.0. TAP and NAP was present in 136(74.3%) and 47(25.7%), with a meanMBFRof 2.19(0.51) and 2.21(1.54), respectively (p=0.93). There was no correlation between chest pain type and global or regional MBFR. Regression modelling incorporating sex, total plaque length (TPL) and inflammatory markers, showed no association between chest pain type and global or regional MBFR. Log TPL (=-0.21, CI:-0.32,-0.10, P=0.001), log hs-CRP (=-0.15, CI:-0.26,-0.04, P=0.006), serumtriglyceride (=-0.14, CI:-0.24,-0.04, P=0.008) were inversely related to global and regional MBFR. Conclusion: In patients with CPUCA, chest pain type is not related to reduction in MBFR, despite accounting for gender, plaque presence and inflammation. However, TPL and systemic inflammation are associated with a lower MBFR.<br />