202 Negative CT coronary angiography and long-term outcomes in a population of 100 patients over 13 years

Introduction CT coronary angiography (CTCA) is a first line investigation for suspected angina. Absence of epicardial coronary artery disease (CAD) on CTCA ("negative CTCA") carries a good medium term prognosis for cardiovascular outcomes. There is less data on long-term outcomes including development of CAD and adverse events. It is increasingly recognised that ischaemia with non-obstructed coronary arteries, including coronary microvascular dysfunction (CMD), can lead to significant morbidity. Here, we assess the long-term outcomes of patients with a negative CTCA performed at our centre in 2010. Methods We performed a retrospective cohort analysis in all patients with a negative CTCA in 2010. Patient demographics and outcomes were reported from electronic patient records. The primary outcome was a composite of non-fatal myocardial infarction (MI), unplanned revascularisation, and all-cause mortality. Secondary outcomes included hospital admission, repeat outpatient assessment, and repeat investigation of suspected CAD. Results 100 patients were identified (table 1). Most (79%) were referred for investigation of chest pain. The majority (67%) were diagnosed with non-cardiac chest pain (table 2). At 13 years follow-up, the incidence of the composite primary outcome was 9% (figure 1), driven by all-cause death (7%). Two patients (2%) underwent revascularisation for non-fatal MI (one in the context of ST elevation myocardial infarction). The median (IQR) time to primary outcome was 9.8 (8.1–11.5) years. 22 (22%) patients were admitted on a total of 41 occasions, requiring 68 bed days (figure 2). 47 (47%) patients were re-referred for outpatient cardiology review for a cumulative total of 117 clinic appointments. Further investigations were frequently performed: CTCA was repeated in 21 (21%) patients; only 1 showed significant CAD. 30 patients underwent further functional testing: 17 (17%) exercise electrocardiographic stress tests (exercise ECG), and 2 myocardial perfusion scintigraphy. 13 (13%) underwent invasive angiography, and two (2%) patients required revascularisation as above. 2 of the 17 (12%) patients had positive exercise ECGs (>0.1 mV ST depression), and 3 (18%) had chest pain without ECG changes. This is relevant given recent evidence that positive exercise ECGs without epicardial CAD may be specific for CMD. Conclusion We demonstrate that negative CTCA is associated with a low incidence of adverse cardiovascular events and all-cause death, akin to the expected rate for this cohort over long-term follow-up. A subset of patients continue to be symptomatic, with high healthcare utilisation and negative repeat cardiac investigations. Despite the absence of epicardial CAD and a positive prognosis, such patients may harbour diagnoses such as CMD: identifying this is important to deliver counselling and medical therapy. Retroactively identifying such patients may be of value as medical and interventional treatment of CMD evolves. Conflict of Interest None