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

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 the prognostic value of QP-CMR in patients with heart failure (HF).

QP-CMR data from 641 prospectively recruited patients with HF and 184 healthy volunteers were analysed. 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. 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 hazard ratio per 1 mL/g/min increase, 3.97, 95% confidence interval [CI] 1.93-8.16, P < 0.001) and MPRuncorr (adjusted hazard ratio 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).

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.