Heartbeat: weather, air pollution and cardiac arrest

Outcomes of patients with an out-of-hospital cardiac arrest (OHCA) remain poor despite considerable efforts in many countries directed towards rapid access defibrillation, emergency medical services and advanced supportive care in those who survive to reach the hospital. Clearly, out long-term goal should be prevention of OHCA which requires an understanding of the environmental factors contributing to this condition, as well as prevention at the individual patient level. In a study from Korea of 38 928 OHCAs due to cardiac disease, Kim and colleagues1 found significant associated between OHCA and average temperature in the summer, temperature range in the winter and particulate matter (PM) ≤2.5 µm (PM2.5) air pollution levels. However, only PM2.5 was independently associated with the risk of OHCA regardless of seasonal changes (figure 1). Figure 1 Generalised additive model with cubic splines for the effects of selected meteorological factors on the number of out-of-hospital cardiac arrests (OHCA). The BOLD line estimates the relative effect sizes for OHCA, and the blue area estimates 95% CIs. The X-axis represents selected meteorological factors. The Y-axis shows the relative effect sizes for OHCA. PM2.5, particulate matter ≤2.5 µm. In an editorial, Chatterjee2 puts this data in the context that air pollution and meteorological factors have previously been shown to be associated with cardiovascular mortality and morbidity, including arrhythmias and heart failure. The current study provides robust data that OHCA also is affected by these environmental conditions, although data on the specific underlying arrhythmic mechanism was not available in most cases. Looking forward, ‘Studies such …