Cardiac NAD+ depletion creates a cascade of mitochondrial dysfunction, elevated reactive oxygen species, and cardiomyocyte death — with the rate-limiting salvage enzyme NAMPT (nicotinamide phosphoribosyltransferase) identified as a central leverage point for restoring NAD+/NADH redox balance in failing hearts. NAD+-dependent sirtuins further link circadian NAMPT oscillation to metabolic regulation, suggesting heart failure pathology intersects with disrupted biological clock signaling. Precursors under clinical evaluation include nicotinic acid (NA), nicotinamide (NAM), NMN, and NR.
This review arrives as NAD+ biology has become one of the most competitive arenas in cardiovascular and longevity research. The NAMPT-sirtuin-circadian axis highlighted here adds meaningful mechanistic texture beyond the simple "replenish NAD+ with supplements" narrative dominating popular science. What's clinically significant is the emerging rationale for targeting NAMPT activation rather than flooding cells with precursors — a potentially more precise therapeutic strategy. However, this is a narrative review, not original data, which limits its evidentiary weight. The field still lacks large randomized controlled trials establishing whether NMN or NR meaningfully reduces hard cardiovascular endpoints in humans. Most mechanistic evidence remains animal-derived or from small human studies. For health-conscious adults, the mechanistic case for NAD+ precursor supplementation in cardiac health is strengthening, but remains confirmatory rather than definitive — placing this squarely in the "promising but not proven" category for clinical translation.
