Non-invasive Ischaemia Testing in Patients With Prior Coronary Artery Bypass Graft Surgery: Technical Challenges, Limitations, and Future Directions

Coronary artery bypass graft (CABG) surgery effectively relieves symptoms and improves outcomes. However, patients undergoing CABG surgery typically have advanced coronary atherosclerotic disease and remain at high risk for symptom recurrence and adverse events. Functional non-invasive testing for ischaemia is commonly used as a gatekeeper for invasive coronary and graft angiography, and for guiding subsequent revascularisation decisions. However, performing and interpreting non-invasive ischaemia testing in patients post CABG is challenging, irrespective of the imaging modality used. Multiple factors including advanced multi-vessel native vessel disease, variability in coronary hemodynamics post-surgery, differences in graft lengths and vasomotor properties, and complex myocardial scar morphology are only some of the pathophysiological mechanisms that complicate ischaemia evaluation in this patient population. Systematic assessment of the impact of these challenges in relation to each imaging modality may help optimize diagnostic test selection by incorporating clinical information and individual patient characteristics. At the same time, recent technological advances in cardiac imaging including improvements in image quality, wider availability of quantitative techniques for measuring myocardial blood flow and the introduction of artificial intelligence-based approaches for image analysis offer the opportunity to re-evaluate the value of ischaemia testing, providing new insights into the pathophysiological processes that determine outcomes in this patient population

MRI provision for patients with cardiac implantable electronic devices: understanding the real-world administrative requirements of service delivery

Abstract Introduction Patients with cardiac implantable electronic devices (CIEDs) should have access to Magnetic Resonance Imaging (MRI) but are less likely to be referred and hospitals lack provision. A major barrier to service delivery is the administrative demand required to obtain accurate CIED details prior to scheduling. We aimed to understand the administrative requirements of a high-volume Cardiac Device-MRI service to inform the design of an electronic referrals platform that can facilitate workflow. Methods Single centre retrospective audit of a high-volume Cardiac Device-MRI service in a tertiary unit in the UK. Six months of referrals were reviewed for patient and CIED details and barriers met. Referrals were stratified by source, indication, MR-Conditional labelling and referrer. Results Administrative barriers were reviewed for 116 patients with CIEDs referred for MRI (48% cardiac, 52% non-cardiac) between September 2020 and March 2021 (Table 1). Referrers were 47% cardiologists and 53% other specialties. Referral to scan time was 15 days (interquartile range, 8–32). There were no scan-related complications. 34% of referrals contained complete CIED details and 30% stated the MR labelling of the CIED. None incorrectly labelled a CIED as MR-Conditional, but 8% incorrectly labelled as non-MR Conditional. 7 additional days were required to obtain complete CIED details where not provided (involving information requests from two device clinics in 27%), 10% had delays over 2 weeks (maximum 145 days). 35% required 3 or more repeat discussions with referrers after initial referral. Obtaining CIED information for external referrals required 17 days (11–42), compared to 14 (6–35) days for internal referrals (p=0.25). Patients with non-MR Conditional CIEDs required on average 14 days longer to obtain complete referral details than patients with MR-Conditional CIEDs. Even when referrers were aware of non-MR Conditional labelling and received information on risk, 41% required further discussion between patient and referrer regarding risks and benefits of MRI scanning. For cancer referrals, obtaining correct details took 1 day longer than other referrals (p=0.074) and required 2 extra emails to maintain provision within the national time-to-treatment target of 62 days. Missing data was similarly present in referrals from Cardiologists and non-Cardiologists (59% versus 61% respectively), but non-Cardiologists recorded more incorrect CIED details (8% vs 0%). Conclusions Referral for MRI in patients with CIEDs demands significant administrative input to obtain correct device information, leading to delays. These delays are greater for patients with non-MR conditional CIEDs, and data provided is often incorrect or incomplete. This may explain why some patients are not referred for MRI. An online referrals platform has been developed to streamline this process, initially deployed through a network of 60 centres registered in the UK. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): This work is supported by British Heart Foundation Innovations funding (HFHF_016). </jats:sec

Non-invasive Ischaemia Testing in Patients With Prior Coronary Artery Bypass Graft Surgery: Technical Challenges, Limitations, and Future Directions

Coronary artery bypass graft (CABG) surgery effectively relieves symptoms and improves outcomes. However, patients undergoing CABG surgery typically have advanced coronary atherosclerotic disease and remain at high risk for symptom recurrence and adverse events. Functional non-invasive testing for ischaemia is commonly used as a gatekeeper for invasive coronary and graft angiography, and for guiding subsequent revascularisation decisions. However, performing and interpreting non-invasive ischaemia testing in patients post CABG is challenging, irrespective of the imaging modality used. Multiple factors including advanced multi-vessel native vessel disease, variability in coronary hemodynamics post-surgery, differences in graft lengths and vasomotor properties, and complex myocardial scar morphology are only some of the pathophysiological mechanisms that complicate ischaemia evaluation in this patient population. Systematic assessment of the impact of these challenges in relation to each imaging modality may help optimize diagnostic test selection by incorporating clinical information and individual patient characteristics. At the same time, recent technological advances in cardiac imaging including improvements in image quality, wider availability of quantitative techniques for measuring myocardial blood flow and the introduction of artificial intelligence-based approaches for image analysis offer the opportunity to re-evaluate the value of ischaemia testing, providing new insights into the pathophysiological processes that determine outcomes in this patient population.</jats:p