Coronary physiology: The importance of invasive coronary physiology in the real-world setting and the interaction between invasive coronary physiological indices

Abstract

This thesis explores the practical implications and outcomes associated with the use of coronary physiology measurements, specifically focusing on the relationship between macrovascular and microvascular indices. Despite extensive data from randomised clinical trials supporting FFR, there is limited real-world evidence, particularly in the Australian context.

To address this gap, a large cohort study was conducted, comparing outcomes of patients undergoing coronary angiography with and without FFR measurement. The study involved 34,597 patients, with 1,734 undergoing FFR-guided angiography. The findings highlight the clinical benefits and enhanced decision-making facilitated by FFR, promoting its use in routine practice. Furthermore, the study examines the outcomes of FFR usage preceding coronary artery bypass grafting (CABG), an area with sparse existing data.

Beyond FFR, the research investigates ratios such as instantaneous wave-free ratio (iFR) and quantitative flow ratio (QFR), assessing their diagnostic accuracy and correlation with FFR. The prospective enrolment of patients allowed for a comprehensive comparison, revealing that NHPRs, while useful, require careful interpretation in contexts with altered microcirculatory function.

The thesis also delves into the intricate relationship between macrovascular and microvascular indices, including the index of microcirculatory resistance (IMR) and coronary flow reserve (CFR). Through correlation analysis, it was found that NHPRs relate significantly to resistive reserve ratio (RRR), indicating their ability to provide insights into both stenosis and resting autoregulation.

In summary, this research underscores the importance of integrating coronary physiological indices in real-world clinical settings, offering novel insights into their interrelationships and impact on patient outcomes. The findings advocate for the broader adoption of these measurements to enhance the precision of CAD assessment and treatment.