Instantaneous wave-free ratio for guiding treatment of nonculprit lesions in patients with acute coronary syndrome: A retrospective study.

Background: The aim of this study was to analyze the feasibility of a physiological coronary evaluation with the instantaneous wave-free ratio (iFR) of nonculprit lesions in patients with acute coronary syndrome (ACS) successfully revascularized.

Methods: A multicenter registry including patients of four high-volume PCI centers with ACS and underwent successful revascularization of the culprit vessel and had other nonculprit lesions that were physiologically evaluated with the iFR between January 2017 and December 2019. The primary endpoint was a composite of cardiac death, nonfatal myocardial infarction, probable or definitive stent thrombosis and new revascularization (MACEs).

Coronary microvascular dysfunction assessed by continuous intracoronary thermodilution: A comparative study with index of microvascular resistance.

Background: This study aimed to assess the correlation between the standard of care, the index of microvascular resistance (IMR) versus the novel microvascular resistance (R) and to determine the pathologic cut-off value in a selected population with suspected coronary microvascular dysfunction (CMD).

Methods: One-hundred and twenty patients with high clinical suspicion of CMD due to ischemic symptoms in the absence of significant epicardial coronary lesions were prospectively included. Following a standardized systematic protocol, coronary flow reserve, IMR, fractional flow reserve, Q and R were measured in the left anterior descending coronary artery using a temperature/pressure sensor-tipped guidewire and a dedicated infusion catheter.

Continuous Thermodilution Method to Assess Coronary Flow Reserve.

Coronary flow reserve (CFR) is a well-validated flow-based physiological parameter that has shown value in clinical risk stratification. CFR can be invasively assessed, classically by Doppler and, more recently, by thermodilution with saline boluses (CFR). Alternatively, continuous thermodilution is a novel operator-independent, highly-reproducible technique to invasively quantify maximum absolute coronary flow (AF).