Non optimal temperatures and chronic cardiovascular diseases.

Extreme temperatures are emerging as major climate-sensitive drivers of chronic cardiovascular disease (CVD). Global warming has increased the frequency, duration, and intensity of heatwaves, while substantial cold-related risk persists, particularly in poorly insulated and socioeconomically vulnerable settings. Together, non-optimal temperatures account for millions of deaths annually, with a large and growing share attributable to CVD. In this narrative review, we synthesize epidemiological, mechanistic, and systems-level evidence linking heat and cold exposure to chronic cardiovascular outcomes, with a focus on ischemic heart disease, stroke, heart failure, and arrhythmias. We first outline key temperature metrics, shifting climate patterns, and challenges in exposure assessment, including the roles of humidity, diurnal variability, and indoor versus outdoor environments. We then summarize the epidemiology of temperature, CVD associations across diverse regions, highlighting U- and J-shaped exposure-response curves and disproportionate impacts in low- and middle-income countries, older adults, and socioeconomically disadvantaged communities. Mechanistic sections examine how heat and cold drive autonomic imbalance, endothelial dysfunction, oxidative stress, inflammation, haemoconcentration, changes in coagulation, renal injury, and myocardial oxygen supply-demand mismatch. We further discuss modifying effects of air pollution, wildfires, dust storms, and medication use, including clinically relevant drug-heat interactions in patients with chronic CVD. Finally, we review heat-health and cold-health action plans, health-system resilience frameworks, and emerging research gaps spanning exposure science, mechanistic studies, vulnerable populations, and policy evaluation. Recognising non-optimal temperature exposure as a modifiable environmental risk factor for chronic CVD is essential. Integrating climate-informed prevention, clinical care, and adaptation strategies offers substantial and timely opportunities to reduce cardiovascular burden in a warming and increasingly unstable climate.