Background: Previous studies have demonstrated a modest inverse relationship between defibrillator therapies for ventricular tachyarrhythmias and geomagnetic activity (GMA) which is primarily affected by solar storms.
Hypothesis: There is a difference between the frequency of reported sudden cardiac arrests in days of normal solar activity versus days with solar storms.
Methods: Population based data from the Emergency Response System of the metropolitan city of Prague, Czech Republic (serving stable population of 1.26 million people) were collected on all reported out of hospital sudden arrests which required emergent medical response between 2003 and 2013. Bradycardic arrests were excluded. Frequency of arrests and presenting ECG rhythms were compared to GMA activity (quiet days versus storm days based on planetary Kp and Ap indices reported for Central Europe) based on previously established GMA benchmarks.
Results: GMA records showed 2325 (59.7% of all days) quiet days, and 182 (4.7%) storm days during the study period, and a total of 4693 arrests occurred. Distribution of arrest stratified by GMA (Table 1) showed modestly lower rate of events on storm days compared to the quiet days (p=0.003). This trend was seen in all presenting rhythms, and most pronounced in patients presenting with asystole.
Conclusions: In this population based study we observed modest trend favoring lower frequency of cardiac arrests on days with high solar activity. These data are congruent with previous studies focusing on ventricular tachyarrhythmias in patients with implantable cardioverter defibrillators. Further investigation of the potential underlying mechanisms is substantiated.