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.jpg "Moritz C. Halfmann, MD photo")
Moritz C. Halfmann, MD
Radiology Resident
University Medical Center Mainz
Mainz, Rheinland-Pfalz, Germany
Theresia Schoeler, MD
Radiology resident
University Medical Center Mainz, Germany
Akos Varga-Szemes, MD, PhD
Associate Professor of Radiology
Medical University of South Carolina, United States
Göbel Sebastian, MD
Cardiology Consultant
University Medical Center Mainz, Germany
Tilman Emrich, MD
Junior Consultant
University Medical Center Mainz
Mainz, Rheinland-Pfalz, Germany
MRI T2 mapping has been proven to be sensitive to the level of blood oxygenation. We hypothesized that impaired exercise capacity in heart failure causes greater difference between right (RV) to left ventricular (LV) blood pool T2 relaxation times due to a higher level of peripheral blood desaturation, compared to patients with preserved exercise capacity and to healthy controls.
Methods:
Patients with heart failure (n=70) who had previously undergone both cardiac MRI (CMR) and a 6-minute walk test (6MWT) within 69 ± 49 days were retrospectively identified. Propensity score matched healthy individuals (n=35) served as a control group. CMR analyses included cine acquisitions and T2 mapping to obtain blood pool T2 relaxation times of the RV and LV. As common practice, age- and gender-adjusted nominal distances and respective percentiles were calculated for the 6MWT. The relationship between the RV/LV T2 blood pool ratio and the results from 6MWT were evaluated by Spearman's correlation coefficients and linear regression analyses. Inter-group differences were assessed by independent t-tests and univariate analysis of variance.
Results:
The RV/LV T2 ratio strongly correlated with the percentiles of nominal distances in the 6MWT (r=0.66) while ejection fraction, end-diastolic and end-systolic volumes showed no correlation (r=0.09, 0.07 and -0.01, respectively). In addition, there were significant differences in the RV/LV T2 ratio between patients with and without significant post-exercise dyspnea (p=0.001). Logistic regression analysis showed that RV/LV T2 ratio was an independent predictor of the distance walked and the presence of post-exercise dyspnea (p < 0.001).
Conclusion:
The proposed RV/LV T2 ratio, obtained by two simple measurements on a routinely acquired four-chamber T2 map, was superior to established parameters of cardiac function to predict exercise capacity and the presence of post-exercise dyspnea in patients with heart failure.