Health outcomes in patients with chronic coronary syndromes due to obstructive or non-obstructive coronary arteries

Abstract

Abstract Background Angina is the clinical hallmark of myocardial ischaemia and often arises from obstructive coronary artery disease (diagnosed as stable CAD), for which there are established guideline therapies. However, when coronary angiography does not reveal obstructive CAD (i.e. <50% stenoses), the management pathway for these patients with Angina with Non-Obstructive Coronary Arteries (ANOCA) is less clear. Purpose To compare the clinical characteristics and outcomes of patients with Stable CAD vs. ANOCA, who were referred to invasive angiography for the assessment of angina. Methods Consecutive angina patients undergoing elective coronary angiography enrolled in the CADOSA (Coronary Angiogram Database of South Australia) Registry between 2012-2018 were included. In-hospital clinical data was extracted from CADOSA and mortality and hospitalisation data over 3 years was extracted via administrative records. Results Among 30,015 angiograms performed, there were 2,245 ANOCA (<50% stenosis), and 4,131 Stable CAD (≥50% stenosis) patients. ANOCA patients were younger (61±11 vs 66±11, p<0.05) and more often female (59% vs 27%, p<0.05) compared to Stable CAD. ANOCA and Stable CAD patients were indistinguishable in relation to (i) chest pain quality (tightness, 42% vs 41%, p>0.05) (ii) chest pain precipitant (exertion, 60% vs 65%, p<0.05), (iii) relieving factors (nitrates 20% vs 22%, p>0.05). Further, the frequency of non-invasive ischaemia test prior to angiography (64% vs 62%, p<0.05) and objective evidence of ischaemia (70% vs 77%, p>0.05) was similar between ANOCA and Stable CAD. In contrast, discharge therapies differed markedly between ANOCA and Stable CAD patients in (i) cardioprotective agents (81% vs 96%, respectively), and (ii) anti-ischaemic agents (75% vs 90%, respectively), all p<0.05. Only 6% of ANOCA patients received further cardiac investigation whereas revascularisation was undertaken in 35% of the Stable CAD cohort. All-cause mortality at 3 years was higher in Stable CAD patients compared to ANOCA (3% vs 2%, p<0.05). There were frequent return hospital visits for chest pain in both Stable CAD and ANOCA patients over 3 years including (i) emergency presentation (24% vs 18%, respectively) and (ii) hospital admission (18% vs 11%, respectively), all p<0.05. Conclusion Prior to angiography, the chest pain features, and non-invasive ischaemic markers are indistinguishable in ANOCA and Stable CAD patients. However, following angiography, Stable CAD patients receive an appropriate diagnosis and guideline therapy. In contrast, the ANOCA patients (a) seldom receive additional investigation to identify the underlying angina mechanisms, (b) are less often prescribed cardioprotective and anti-anginal agents, (c) yet often experience recurrent symptoms. This study underscores the need to focus improvement on diagnostic work-up for ANOCA and therapies targeted at managing symptoms.