Question: Why are there so many recommendations for the treatment of systolic heart failure and so few for diastolic heart failure management?
Answer: Well, I think the main reason is the wealth of clinical trial data that's has been derived from thousands and thousands of patients who've been enrolled in trials of systolic heart failure -- a very clear cut and definitive answers for what works and what doesn't in this patient population. The number is much smaller for diastolic heart failure and the agents which work very well for systolic failure have had more equivocal borderline results in the diastolic population.
The other key reason lies in our fundamental understanding of what causes the different forms of heart failure which appear to be somewhat different. In systolic heart failure, the heart can't squeeze blood properly to the body, whereas in diastolic heart failure, the heart becomes stiffened and the blood vessels also stiffen. This decreases the ability of the heart to fill with blood and also makes the blood pressure shift far to the high and to the low which may lead to exaggerated shifts in fluid volume in the body.
Because these are such disparate diseases and behave different clinically, it may be that people need more tailored therapy and this is more difficult to define in a trial population.
So I think as more and more clinical trial data comes in, we'll have a better understanding for which therapies are most effective in this patient population. We'll have much better evidence to fuel the guidelines. We also need much more trial data that supports the different causes so that we can really identify which mechanisms are most specific to the diastolic form of heart failure in order to achieve better therapeutic responses.