<p>Microplastics and nanoplastics (MNPs) are pervasive environmental pollutants that result from the degradation of plastic materials and the use of plastic-containing products. Although the accumulation of MNPs in the gastrointestinal and respiratory systems is well documented, growing evidence suggests that MNPs can translocate into the bloodstream and accumulate in cardiovascular tissue, raising concerns about their potential role in the development of cardiovascular disease. In this Review, we synthesize the current knowledge on MNP exposure routes, tissue distribution and biological effects relevant to cardiovascular health. We examine the latest clinical and experimental studies on the presence of MNPs in the blood, atherosclerotic plaques, thrombi and myocardial tissue, and critically evaluate the mechanistic evidence linking MNPs to endothelial dysfunction, atherosclerosis progression, myocardial injury and arrhythmogenesis. In vitro and in vivo data highlight plausible pathophysiological pathways linking MNPs to cardiovascular disease, including oxidative stress, mitochondrial dysfunction, inflammation and fibrotic remodelling. However, causal associations remain unproven in humans, and major methodological challenges persist, including inconsistent detection methods, limited epidemiological data and inadequate modelling of real-world exposure. We conclude by outlining research priorities and proposing a framework for how to integrate MNPs into environmental cardiology practice. As the global issue of plastic pollution intensifies, elucidating the cardiovascular risks posed by MNPs represents an urgent interdisciplinary challenge with substantial public health implications.</p>