I've had breathlessness on exertion for years, but it's getting worse. Echo EF & BNP both normal. How is diastolic heart failure diagnosed/ruled out?

Nonsystolic HF. Nonsystolic heart failure or diastolic dysfunction means that the heart is operating inefficiently in the relaxation phase. This occurs because of damage to heart muscle by untreated hypertension, or from other causes. Exertional breathlessness has many other causes besides heart failure, & if you've had the heart checked already it may be time to look at lungs etc. A consult on HealthTap may help.