Can there be any relation between elevated heart rate and diastolic dysfunction?

Unlikely: Diastolic dysfunction refers to stiffening of the heart, does not relax properly. Measuring this however is very complicated and the tests for it by echo are riddled with confounding factors such as age and hydration status. The use if tissue doppler imaging can help clarify this a little. Usually it is part of the echo report. However not all echo labs use it.