PURPOSE: This study aims to assess microvascular dysfunction in women with Syndrome-X when compared to age-controlled healthy women utilizing OS-CMR.
METHODS: Fourteen Syndrome-X patients (mean age 54.6+/-6.58 years) and eighteen age-controlled healthy participants (mean age 52.7+/-3.90 years) underwent a CMR scan on a 3T Siemens scanner. Functional parameters were obtained from 2- and 4-chamber long axis standard SSFP cine images using the biplanar method. OS-CMR parameters were obtained from Oxygenation Sensitive (OS) images obtained in the basal and mid-ventricular short-axis. A combined breathing maneuver of 60 seconds of paced hyperventilation followed by a maximal breath-hold was performed. Global MORE values were obtained as a percent change in signal intensity from the beginning of the breath hold to the 30 second timepoint. Three methods were used to assess regional homogeneity. Radial difference, circumferential difference, and combined difference OS values were obtained from analyzing the endocardial and epicardial layers of the myocardium independently. Radial difference is the sum of the absolute differences between the endo- and epicardium in each of the myocardial segments. Circumferential difference is the sum of the differences between myocardial segments within the endo- and epicardium. Combined difference is a sum of radial and circumferential differences.
RESULTS: There was no significant difference in age, body mass index, body surface area, or cardiac output between the Syndrome-X and the healthy control participants. Syndrome-X patients had a significantly lower left ventricular ejection fraction than healthy control participants (76.45+/-6.88 vs. 71.5+/-5.89, p<0.05). Global myocardial oxygenation reserve values were not significantly different in Syndrome-X (6.90+/-6.59) when compared to healthy controls (5.06+/-4.47). Syndrome-X patients had a significantly higher radial (p=0.026), circumferential (p=0.0037), and combined difference (p=0.0026) when compared to healthy participants.
CONCLUSIONS: While the global myocardial oxygenation response between women with Syndrome-X and healthy control women was not significant, significant heterogeneity within the myocardium is present. This may indicate that heterogenous microvascular dysfunction is present in this patient population.