Impact of rate-pressure product correction of myocardial blood flow on the prognostic relevance in patients with heart failure

AIMS: Quantitative perfusion cardiac magnetic resonance (QP-CMR) allows estimation of myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). Resting MBF values are often corrected for the rate pressure product (RPP). We aimed to assess the effect of RPP correction on MBF values and prognostic value of QP-CMR in patients with heart failure (HF). METHODS: QP CMR data from 641 prospectively recruited patients with HF and 184 healthy volunteers were analyzed. Rest MBF was corrected for RPP (MBFcorr = rest MBFuncorr×10,000/RPP). Corrected MPR was defined as uncorrected stress MBF/rest MBFcorr. The primary endpoint was a composite of heart failure hospitalization (HFH) and all-cause mortality. RESULTS: RPP correction increased rest MBF and decreased MPR to a greater extent in healthy volunteers than in patients. During median follow-up of 3.5 years, 101 events occurred (55 deaths and 46 HFH). Patients who reached the primary endpoint had significantly higher rest MBFuncorr and lower MPRuncorr. Rest MBFuncorr (adjusted HR per 1 mL/g/min increase, 3.97, 95% CI 1.93-8.16, p < 0.001) and MPRuncorr (adjusted HR per 1 unit increase, 0.74, 95% CI 0.57-0.95, p = 0.024) were significantly associated with the primary endpoint in univariate and multivariate models. After RPP correction, these associations were no longer significant. Kaplan-Meier analysis revealed significant differences in event-free survival for rest MBFuncorr (p = 0.005), MPRuncorr (p < 0.001), and MPRcorr (p = 0.044), but not for rest MBFcorr (p = 0.076). CONCLUSIONS: Uncorrected rest MBF and MPR by QP-CMR are independently predictive of adverse outcomes in patients with HF. RPP correction changes MBF and MPR values and attenuates their predictive value.