Letter by Poullis Regarding Article, “Prognostic Value of the Index of Microcirculatory Resistance Measured After Primary Percutaneous Coronary Intervention”
To the Editor:
I read with interest the article by Fearon et al,1 which presents an important consecutive series correlating index of microcirculatory resistance (IMR) with prognosis after primary percutaneous coronary intervention. Their work raises a number of issues:
No correlation between myocardial damage, enzymatic or functional, and IMR is made. A small myocardial infarct could have the same IMR as a large one because the index is a ratio, not an absolute measurement. The same error may occur with coronary flow reserve.
The prognoses for single-vessel and multi-vessel disease are different. The …