myocardial salvage index
Also written as: MSI — Myocardial Salvage Index
A cardiac MRI metric quantifying the amount of myocardium saved from infarction following acute intervention, expressed as the ratio of salvaged tissue to the area at risk.
Full Definition
The myocardial salvage index is a quantitative cardiac MRI measurement that evaluates the effectiveness of acute cardiac intervention by calculating the proportion of myocardium that was saved from permanent damage. It is derived by subtracting the final infarct size from the initial area at risk, then dividing by the area at risk, typically expressed as a percentage. This metric requires both T2-weighted imaging to identify myocardial edema (area at risk) and late gadolinium enhancement imaging to determine final infarct size. The salvage index is considered a superior endpoint for clinical trials as it accounts for both the initial threat and the therapeutic benefit achieved. Higher salvage index values indicate more successful myocardial preservation and better clinical outcomes.
Usage
Usage note: Often abbreviated as MSI in clinical literature; requires careful distinction from myocardial viability assessment, which measures existing tissue function rather than salvaged tissue.
In Context
- "The myocardial salvage index was calculated as 68%, indicating substantial tissue preservation following primary PCI." — Cardiac MRI report
- "Patients with a salvage index above 50% demonstrated significantly better long-term ventricular function recovery." — Clinical research paper