First-in-Human Experience With a Novel Monorail Microcatheter for Instantaneous Coronary Pressure and Flow Velocity Measurements

Invasive coronary physiology enables comprehensive assessment of epicardial and microvascular disease, but its routine use is limited by technical complexity and prolonged acquisition time. The PyCath system is a rapid-exchange microcatheter engineered to simultaneously measure intracoronary pressure and thermoconvection-based flow velocity. First-in-human, prospective, single-arm study evaluating the safety and performance of the PyCath system in patients with a clinical indication for coronary physiology assessment. The microcatheter was advanced over a standard coronary guidewire to acquire simultaneous pressure and flow velocity at baseline and during hyperemia. The primary objectives were procedural safety, defined as device-related major adverse cardiac events, and device performance, defined as successful acquisition of pressure and velocity signals. Data were analyzed by an independent core laboratory. Seventeen patients (mean age 59.3 ± 9.4 years, 76.5% males) referred for invasive coronary physiology assessment were included. Intracoronary pressure and velocity measurements were feasible in 100% and 88% of cases, respectively. The mean time required to obtain both measurements was 70.6 ± 23.6 seconds. The mean fractional flow reserve, coronary flow velocity reserve, and hyperemic microvascular resistance were 0.84 ± 0.12, 2.28 ± 0.79, and 1.46 ± 0.77, respectively. There were no device-related major adverse cardiac events. Test-retest reproducibility was good-to-excellent with intraclass correlation coefficients for fractional flow reserve, coronary flow velocity reserve, and hyperemic microvascular resistance of 0.979 (0.934-0.993), 0.798 (0.477-0.933), and 0.759 (0.397-0.919). In this first-in-human experience, the PyCath microcatheter enabled safe and reproducible measurements of intracoronary pressure and flow velocity with excellent reproducibility.