title: Correlation of geomagnetic activity with implantable cardioverter defibrillator shocks and antitachycardia pacing.
abstract: OBJECTIVE
  To investigate a potential relationship between implantable cardioverter defibrillator (ICD) therapies and daily geomagnetic activity (GMA) recorded in a large database.
  
  
  METHODS
  The ALTITUDE database, derived from the Boston Scientific LATITUDE remote monitoring system, was retrospectively analyzed for the frequency of ICD therapies. Daily GMA was expressed as the planetary K-index and the integrated A-index and was graded as levels I (quiet), II (unsettled), III (active), and IV (storm).
  
  
  RESULTS
  A daily mean ± SD of 59,468±11,397 patients were monitored between January 1, 2009, and May 15, 2012. The distribution of days according to GMA was as follows: level I, 924/1231 (75%); level II, 226/1231 (18%); level III, 60/1231 (5%); and level IV, 21/1231 (2%). The daily mean ± SD numbers of ICD shocks received per 1000 active patients in the database were 1.29±0.47, 1.17±0.46, 1.03±0.37, and 0.94±0.29 on level I, II, III, and IV days, respectively; the daily mean ± SD sums of shocks and antitachycardia pacing therapies were 9.29±2.86, 8.46±2.45, 7.92±1.80, and 7.83±2.28 on quiet, unsettled, active, and storm days, respectively. A significant inverse relationship between GMA and frequency of ICD therapies was identified, with the most pronounced difference between level I and level IV days (P<.001 for shocks; P=.008 for shocks + antitachycardia pacing).
  
  
  CONCLUSIONS
  In a large-scale cohort analysis, ICD therapies were delivered less frequently on days of higher GMA, confirming the previous pilot data and suggesting that higher GMA does not pose an increased risk of arrhythmias using ICD therapies as a surrogate marker. Further studies are needed to gain an in-depth understanding of the underlying mechanisms.
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN; Department of Medical Sciences, Division of Cardiology, Città della Salute e della Scienza, University of Turin, Turin, Italy.
authors: Elisa
authors: E
authors: Ebrille
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN; International Clinical Research Center, St Anne's University Hospital, Brno, Czech Republic.
authors: Tomas
authors: T
authors: Konecny
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN; International Clinical Research Center, St Anne's University Hospital, Brno, Czech Republic.
authors: Dana
authors: D
authors: Konecny
authors: Department of Internal Medicine, Hospital Frýdek-Místek, Frýdek-Místek, Czech Republic.
authors: Radim
authors: R
authors: Spacek
authors: Boston Scientific, St Paul, MN.
authors: Paul
authors: P
authors: Jones
authors: Astronomical Institute of the Academy of Sciences of the Czech Republic, Ondrejov.
authors: Pavel
authors: P
authors: Ambroz
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors: Christopher V
authors: CV
authors: DeSimone
authors: Division of Cardiovascular Diseases, Sanger Heart & Vascular Institute, Charlotte, NC.
authors: Brian D
authors: BD
authors: Powell
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors: David L
authors: DL
authors: Hayes
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors: Paul A
authors: PA
authors: Friedman
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN; Department of Pediatrics and Adolescent Medicine, Mayo Clinic, Rochester, MN. Electronic address: asirvatham.samuel@mayo.edu.
authors: Samuel J
authors: SJ
authors: Asirvatham
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology* / Q000628:therapy; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000379:methods; D005260:Female; D006801:Humans; D060328:Magnetic Phenomena; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D012189:Retrospective Studies