There is usually the rule of thumb that such samples are usually only stable for 24-72 at ambient or refrigerated temperature and need analyzing within this time period

You can give it a try, but the RNA quality may not be that great, therefore, the RNA might not be suitable for all downstream applications, e.g. RNA-seq.

Thanks all , but  I need for qRT Pcr

I would just go ahead and try and extract from a couple of samples then, nothing to lose and just check the RNA quality on a Bioanalyzer before proceeding with  your qRT PCR . On your side it has  been shown that the RNA yield is higher in EDTA-blood than in heparin-blood (see attached pdf might be of help). 

 Cheers

Thanks  again