Key result
RV/LV T2 blood pool ratio moderately correlates with 6MWT distance and predicts post-exercise dyspnea.
Why the study?
MRI T2 mapping reflects blood oxygenation, prompting the hypothesis that impaired exercise capacity in chronic heart failure is associated with greater RV-to-LV blood pool T2 differences due to peripheral blood desaturation.
Does the cardiac MRI-based RV/LV blood pool T2 relaxation times ratio correlate with exercise capacity in patients with chronic heart failure?
Observational (n=105)
Does the cardiac MRI-based RV/LV blood pool T2 relaxation times ratio correlate with exercise capacity in patients with chronic heart failure?
The RV/LV T2 ratio derived from routine cardiac MRI T2 mapping is a superior predictor of exercise capacity and post-exercise dyspnea in chronic heart failure compared to standard volumetric parameters.
Answers are grounded in this paper and cite their sources.
RV/LV T2 ratio may aid functional assessment in HF; hypothesis-generating and requires prospective validation before clinical use.
BACKGROUND: MRI T2 mapping has been proven to be sensitive to the level of blood oxygenation. We hypothesized that impaired exercise capacity in chronic heart failure is associated with a 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 chronic heart failure (n = 70) who had undergone both cardiac MRI (CMR) and a 6-min walk test (6MWT) were retrospectively identified. Propensity score matched healthy individuals (n = 35) served as control group. CMR analyses included cine acquisitions and T2 mapping to obtain blood pool T2 relaxation times of the RV and LV. Following 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 regression analyses. Inter-group differences were assessed by independent t-tests and univariate analysis of variance. RESULTS: The RV/LV T2 ratio moderately 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). Regression analyses 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 chronic heart failure.
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Halfmann et al. (2023) conducted an observational in chronic heart failure (n=105). RV/LV T2 blood pool ratio vs. Healthy controls was evaluated on Correlation between RV/LV T2 blood pool ratio and percentiles of nominal distances in the 6MWT (r = 0.66, p=<0.001). The RV/LV T2 blood pool ratio moderately correlated with 6-minute walk test performance (r = 0.66) and independently predicted walked distance and post-exercise dyspnea (p < 0.001).
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