Pre-operative Diagnosis of Silent Coronary Ischaemia May Reduce Post-operative Death and Myocardial Infarction and Improve Survival of Patients Undergoing Lower Extremity Surgical Revascularisation

Abstract

Objective: Patients undergoing peripheral vascular surgery have increased risk of death and myocardial infarction (MI), which may be due to unsuspected (silent) coronary ischaemia. The aim was to determine whether pre-operative diagnosis of silent ischaemia using coronary computed tomography (CT) derived fractional flow reserve (FFR_CT) can facilitate multidisciplinary care to reduce post-operative death and MI, and improve survival.

Methods: This was a single centre prospective study with historic controls. Patients with no cardiac symptoms undergoing lower extremity surgical revascularisation with pre-operative coronary CTA-FFR_CT testing were compared with historic controls with standard pre-operative testing. Silent coronary ischaemia was defined as FFR_CT ≤ 0.80 distal to coronary stenosis with FFR_CT ≤ 0.75 indicating severe ischaemia. End points included cardiovascular (CV) death, MI, and all cause death through one year follow up.

Results: There were no statistically significant differences between CT angiography (CTA-FFR_CT) (n = 135) and control (n = 135) patients with regard to age (66 ± 8 years), sex, comorbidities, or surgery performed. Coronary CTA showed ≥ 50% stenosis in 70% of patients with left main stenosis in 7%. FFR_CT revealed silent coronary ischaemia in 68% of patients with severe ischaemia in 53%. The status of coronary ischaemia was unknown in the controls. At 30 days, CV death and MI in the CTA-FFR_CT group were not statistically significantly different from controls (0% vs. 3.7% [p = .060] and 0.7% vs. 5.2% [p = .066], respectively). Post-operative coronary revascularisation was performed in 54 patients to relieve silent ischaemia (percutaneous coronary intervention in 47, coronary artery bypass graft in seven). At one year, CTA-FFR_CT patients had fewer CV deaths (0.7% vs. 5.9%; p = .036) and MIs (2.2% vs. 8.1%; p = .028) and improved survival (p = .018) compared with controls.

Conclusion: Pre-operative diagnosis of silent coronary ischaemia in patients undergoing lower extremity revascularisation surgery can facilitate multidisciplinary patient care with selective post-operative coronary revascularisation. This strategy reduced post-operative death and MI and improved one year survival compared with standard care.

Keywords: Coronary CT derived fractional flow reserve; Long term survival; Peripheral artery disease; Post-operative mortality; Silent coronary ischaemia; Surgical revascularisation.