Pullback pressure gradients: Redefining the functional landscape of coronary artery disease

Fractional flow reserve (FFR) remains the most widely adopted invasive physiologic index for determining the functional significance of epicardial coronary artery disease (CAD). By applying a validated binary threshold for myocardial ischemia, FFR guides clinical decision-making regarding the need for coronary revascularization. However, CAD is often heterogeneous, with varying patterns of focal and diffuse atherosclerotic involvement that are not fully captured by a single distal FFR value. Assessment of pressure changes along the vessel using hyperaemic pullback recordings provides additional pathophysiologic insight by depicting the spatial distribution of pressure loss as a pullback curve. Traditionally, interpretation of these curves has been largely visual and subjective, resulting in considerable interobserver variability and limited reproducibility. The pullback pressure gradient (PPG) index has emerged as a novel quantitative tool to overcome these limitations. By integrating the magnitude and longitudinal distribution of pressure gradients, PPG characterizes CAD patterns on a continuous scale from 0 to 1, where higher values indicate predominantly focal disease and lower values reflect diffuse disease. This review critically appraises the conceptual framework, clinical evidence, practical implications, and future directions of PPG in contemporary coronary physiology.