Abstract
Objective The index of microvascular resistance (IMR) is an invasive method for quantifying the coronary microvasculature independent of the presence and degree of epicardial stenosis during cardiac catheterization, whereas the Selvester QRS score, which is related to myocardial damage, is a relatively simple and non-invasive measurement procedure. We investigated the relationship between the QRS score and coronary microvascular dysfunction (CMD) assessed via IMR.
Methods Data from 74 patients who underwent invasive coronary physiological measurements were retrospectively reviewed. Using a coronary wire, we measured IMR by the hyperemic mean transit time and distal coronary pressure. We also determined a simplified QRS score following the Selvester QRS score criteria by 12-lead electrocardiography. After determining the best cutoff value for the QRS score to predict IMR ≥25, which was defined as CMD by the Coronary Vasomotion Disorders International Study Group, patients were categorized into the QRS score ≥3 (n=16) and the QRS score 0-2 (n=58) groups.
Results IMR in the QRS score ≥3 group was significantly higher in comparison to the QRS score 0-2 group (31; IQR: 19-57 vs. 20; IQR: 14-29, p<0.01). The percentage of patients with IMR ≥25 in the QRS score ≥3 group was significantly higher than that in the QRS score 0-2 group (69% vs. 34%, p=0.01).
Conclusion A higher QRS score was associated with CMD, as estimated by IMR. The Selvester QRS score is noninvasive parameter that is potentially useful for predicting CMD.
