NR activates SIRT2 ? (hmm not sure, I got to re-listen again)
NR one of 3 precursors to NAD
Out of the 3 precursors NR takes the least amount of ATP to make NAD, so if you have low ATP. in your system.. not lots of NAD
Bad hearts have low ATP, so NR is preferable for NAD

Sirtuins require NAD

NMN not considered a precursor according to Charles Brenner PhD
NR converts to NMN

Questions left:
Does NMN need ATP, so less than NR?
Hmmm... it looks like ATP is used to make NR into NMN... (Low ATP can be an issue for NR?)

http://www.sciencedirect.com/science/article/pii/S0969212600001908

NMN is adenylated to NAD by nicotinamide mononucleotide adenylyl transferase (NMNAT). Two pathways use NR to synthesize NAD. Firstly, ATP can be used to phosphorylate NR, generating NMN, a reaction catalyzed by two isoforms of nicotinamide riboside kinase in mammals (NRK1, 2) (Figure I). Secondly, the glycosidic linkage of NR can be broken by purine nucleoside phosphorylase (PNP), and nicotinamide liberated from this reaction is reuse]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683958/

Ouch my head hurts...

From video: