Our preliminary results demonstrate that we can approve the general feasibility of quantitatively measuring myocardial blood flow (MBF) on a routine basis. We could show a statistically significant increase in MBF in both patient groups together (aortic valve replacement and coronary bypass, n=12) after surgical treatment of the patient (primary outcome). Part of this increase may be attributable to a significant increase of the patients' heart rate. As known from physiology, the rate pressure product (RPP) is a good indicator for the oxygen consumption of the heart, leading to the need of a higher perfusion with increasing RPP. Consequently, we have normalized the MBF to the RPP of the individual patient in order to account for these effects. We could also show an increase of these normalized MBF values after surgery, nevertheless, not reaching statistical significance.

As expected, the decrease in left ventricular muscle mass is higher in the aortic valve replacement group than in the bypass surgery group. Also, the end diastolic volume (EDV) decreases distinctly after surgical treatment. Due to the limited number of patients, the decrease in the aortic valve replacement group does not reach statistical significance.

The slight average increase of the rate pressure product after surgery is mainly caused by the significant increase of the heart rate and the comparatively lower decrease of systolic blood pressure.

In all patient groups we could demonstrate a strong correlation between HR and MBF as well as RPP and MBF (secondary outcome). Our results further  confirm the known relationship between HR and MBF (increase of MBF of approximately 1 ml/100g/min per heart beat).

In conclusion, the study revealed a general increase of MBF after surgical intervention (primary outcome). We could further prove a good correlation between HR and MBF as well as RPP and MBF (secondary outcome).

These first promising findings encourage us to present the final results after the required sample size is reached.