Association Between Geomagnetic Activity and Unsuccessful Out-of-Hospital Cardiac Arrest.

Out-of-hospital cardiac arrests (OHCAs) represent a significant global health challenge, with a survival rate <10%. Recent research has demonstrated that geomagnetic activity (GMA) can disrupt the circadian rhythm. Therefore, GMA may affect patient outcomes after an OHCA event wherein resuscitation is attempted. This study involved a retrospective analysis of the Emergency Medical Services (EMS) patient call records and clinical data collected from the Kaunas (Lithuania) EMS digital databases from 1 January 2016 to 31 December 2021. Multivariate logistic regression was used to analyze the association between GMA and the risk of absence of return of spontaneous circulation (ROSC) on the scene, adjusting for potential confounders. Among the 1,507 patients evaluated, 66.6% were male and 47.2% were aged <70 years. A shockable rhythm (SHR) was identified in 436 patients (28.9%), while only 19.9% of patients in the unsuccessful resuscitation group had an SHR. In patients without SHR, a lower rate of ROSC was observed during the period from the second and subsequent days of a geomagnetic storm (GS) to 2 days after the end of the GS. During these days and on days with higher GMA, SHR was associated with a higher probability of achieving ROSC. The impact of SHR on the ROSC was statistically non-significant in the days of GS onset. The association between the risk of absence of ROSC at the scene and higher GMA levels or different GS periods was modified by SHR, with a stronger effect modification observed in males and in patients with a presumed cardiac cause.