The Short Version
Cold weather is well-established as a risk factor for cardiovascular death, and the general direction of this claim is supported by multiple credible sources. However, the specific figure of "approximately 40,000" traces to a single conference presentation (ACC.26, March 2026) that has not yet been peer-reviewed or independently replicated. The claim also omits that this is a statistical model estimate — not a direct cause-of-death count — and that confounding factors like respiratory infections, holiday behaviors, and socioeconomic conditions may contribute to winter cardiovascular mortality spikes.