Background This investigation used image data generated by an anthropomorphic phantom to determine the minimal 99m Tc rest-stress activity concentration ratio ( R ) able to minimize the ghosting effect in the single-day stress-first myocardial perfusion imaging, using different positions of the perfusion defect (PD), scanners and reconstruction protocols. Methods A cardiac phantom with a simulated PD was imaged under different R using different gamma cameras and reconstruction algorithms. The residual activity from precedent stress administration was simulated by modeling effective half-times in each compartment of the phantom and assuming a delay of 3 hours between the stress and rest studies. The net contrast (NC) of the PD in the rest study was assessed for different R , PD positions and scanner/software combinations. The optimal R will be the one that minimize the NC in the rest images Results The activity concentration ratio R , the position of the PD and the scanner/software combinations were all main effects with a statistically significant impact on the NC, in decreasing order of relevance. The NC diminished significantly only for R values up to 2. No further improvement was observed for NC for R values above 2 and up to 3. NC was significantly higher in anteroseptal than in posterolateral positions of the PD and higher for solid-state cameras. Conclusions A rest-stress activity concentration ratio R of 2 in single-day stress-first myocardial perfusion imaging is enough to achieve the maximum net contrast in the PD. This ratio should be used to optimize patient’s radiation exposure. Electronic supplementary material The online version of this article (10.1007/s12350-020-02290-2) contains supplementary material, which is available to authorized users.

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Purpose To evaluate exercise-based rCR derived outcome predictors in patients referred after TAVR. Methods Data of 434 patients (aged 81±6 years) admitted to an average 3-week rCR program after TAVR (walking, up to 30 minutes of cycling or treadmill session twice daily, respiratory and calistenic training) from January 2009 to December 2017 and home discharged, were retrospectively collected at 10 Italian rCR Division of Istituti Clinici Maugeri SpA. Comorbidity (cumulative illness rated state-comorbidity index) (CIRS-CI) score, echocardiography on admission, Disability (Barthel Index) (BI) score, Morse Fall Scale score (MFS), six minutes walking test distance (6MWT) on admission and discharge and maximal training session intensity (MTSI expressed in METs per minutes) were collected. The mortality was assessed up to 3 years after rCR discharge. Results During a 3-years follow up there were 120 (28%) deaths. At t-test analysis non survivors compared to survivors had significantly higher CIRS CI (p=0.000), MFS score on admission (p=0.008) and discharge (p=0.017), serum creatinine level on admission (p=0.000) and discharge (p=0.000); moreover they had significantly lower BI score on admission (p=0.000) and discharge (P=0.000), left ventricle ejection fraction (p=0.008),6MWT on admission (p=0.001) and discharge (p=0.000) and MTSI (p=0.022) in comparison to survivors. At multivariate logistic stepwise analysis, BI score on admission and serum creatinine level at discharge were the only independent predictors of mortality (Table 1); the AUC of the final logistic model was 0.72. Conclusions Patients attending rCR after TAVR seem to be very old; overall mortality at 3 years follow up in patients discharged home after rCR is substantial. Disability profile on admission (measured by Barthel Index) and impaired renal function on discharge (measured by creatinine levels) are independently correlated to death at long term follow up. Funding Acknowledgement Type of funding source: None

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