Comprehensive assessment of myocardial ischaemia: from vessel to patient

Chronic coronary syndrome (CCS) is accompanied by angina and limitation to the patient’s life. The significance of coronary blood flow reduction is currently best assessed by fractional flow reserve (FFR) as a guide to intervention. The beneficial effect of percutaneous coronary intervention (PCI) in these patients has been challenged, and therefore fresh evaluation of the changes in response to PCI is needed. Using real-world data from 40 patients, detailed examination of coronary anatomy and physiology, using FFR and computational fluid dynamics (CFD) to assess absolute coronary flow, was conducted. Patients not undergoing PCI due to FFR negative lesions comprised the ‘control’ group. A novel method to assess the myocardial ischemic burden and address the global flow reduction named ‘cumulative FFR’ (FFRcum) was developed. Fitness trackers monitored everyday physical activity, and six-minute walk tests were performed, before and three months after the procedure. Questionnaires were used to evaluate the change as reported by the patients. I found a clear and significant physiological improvement following PCI in FFR, hyperaemic stenosis resistance (HSR), microvascular resistance (MVR), absolute flow (which increased 80%) and FFRcum (which increased from 0.72 to 0.83). The change in FFRcum was a predictor of the change in quality of life at follow up. Improvement in spontaneous and observed physical activity, which was highly variable between patients, was minimal, with similar findings in PCI and ‘control' patients. This was also observed with questionnaires in all domains except angina frequency. Taken together, this work shows that physiological improvement (FFR and FFRcum), and absolute flow restoration, are achieved with FFR-guided PCI. However, that does not necessarily result in measured improvement in everyday physical activity, or self-reported general health status, but it does result in improved angina status, at three months. Overall, these findings indicate that physiological improvements in myocardial perfusion produced by PCI tend not to lead to a major change in objective measures of activity or wellbeing in everyday life, but are worth pursuing in terms of angina, specifically.