Cold weather’s effect on cardiac events is one of the most consistently replicated findings in cardiovascular research, and it’s directly relevant to a CVICU specifically. A 2024 study published in the Journal of the American College of Cardiology, led by researchers at Harvard and drawing on more than 120,000 patients in Sweden’s national cardiac registry, found that exposure to lower air temperatures and cold spells was associated with an increased risk of heart attack hospitalization two to six days later — both for STEMI and NSTEMI presentations.

One number worth knowing specifically because of where Great Falls sits: heart failure hospital admissions have been shown to peak when outdoor temperatures fall between 0°C and -10°C (roughly 32°F to 14°F) — squarely inside Montana’s typical winter range, not an extreme cold outlier. Snow shoveling is a specific, well-documented trigger mechanism within that broader pattern: the combination of unaccustomed physical exertion and cold-induced vasoconstriction puts real, measurable strain on the cardiovascular system, and clinicians in colder climates routinely report a rise in cardiac admissions immediately following heavy snowfall.

Worth knowing as a practical nuance: the effect isn’t always same-day. Cold exposure’s impact on cardiac risk can be delayed, sometimes tracing back to a cold spell from one to three weeks earlier — which means a run of admissions in late January may have more to do with a cold snap in early January than with that week’s forecast.