Abstract

Background: Time-to-peak of renal blood flow (TTPr), derived from Tc-99m diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy, is a novel parameter for assessing renal perfusion.

Aims: To evaluate the prognostic significance of TTPr in patients with heart failure (HF).
Study Design: Retrospective, observational cohort study.

Methods: We analyzed 304 patients with HF who underwent Tc-99m DTPA renal scintigraphy to assess TTPr. TTPr values were compared between deceased and surviving patients. Cox regression analyses evaluated the prognostic value of TTPr. Model performance was assessed using the C-index, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Bootstrap internal validation (200 repetitions) generated optimism-corrected estimates, and the Holm–Bonferroni correction accounted for multiple testing in secondary analyses.

Results: During a median follow-up of 790 days, 79 patients (26.0%) died. For short-term outcomes (3-month mortality, n = 7), deceased patients showed a trend toward prolonged TTPr compared with survivors (59 s vs. 27 s, p = 0.008); multivariable analysis was not performed due to limited events. For long-term prognosis, TTPr was an independent predictor, demonstrating the highest corrected C-index among individual predictors (p < 0.001). After bootstrap correction, models incorporating TTPr [BM + TTPr and Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) + TTPr] showed modest but significant C-index improvements for all-cause and cardiovascular mortality (BM + TTPr: corrected ΔC-index = +0.018 and +0.020, both p < 0.01; MAGGIC + TTPr: corrected ΔC-index = +0.040 and +0.062, both p < 0.001), with reduced AIC. After Holm–Bonferroni correction, MAGGIC + TTPr significantly improved IDI at 1, 3, and 5 years for both endpoints (all adjusted p = 0.012), whereas NRI improvements were not statistically significant. Survival analysis using exploratory cut-offs (35 s for all-cause mortality, 33 s for cardiovascular mortality) revealed lower cumulative survival in the prolonged TTPr group (p < 0.05); these cut-offs require external validation.

Conclusion: Time-to-peak of renal blood predicted long-term outcomes in this HF cohort, showing potential incremental value. Prospective validation in broader populations is warranted before clinical implementation.