title: Association of episodic physical and sexual activity with triggering of acute cardiac events: systematic review and meta-analysis.
abstract: BACKGROUND
  Evidence has suggested that physical and sexual activity might be triggers of acute cardiac events.
  
  
  OBJECTIVE
  To assess the effect of episodic physical and sexual activity on acute cardiac events using data from case-crossover studies.
  
  
  METHODS
  MEDLINE and EMBASE (through February 2, 2011) and Web of Science (through October 6, 2010).
  
  
  METHODS
  Case-crossover studies investigating the association between episodic physical or sexual activity and myocardial infarction (MI) or sudden cardiac death (SCD).
  
  
  METHODS
  Two reviewers extracted descriptive and quantitative information from each study. We calculated summary relative risks (RRs) using random-effects meta-analysis and absolute event rates based on US data for the incidence of MI and SCD. We used the Fisher P value synthesis method to test whether habitual physical activity levels modify the triggering effect and meta-regression to quantify the interaction between habitual levels of physical activity and the triggering effect.
  
  
  RESULTS
  We identified 10 studies investigating episodic physical activity, 3 studies investigating sexual activity, and 1 study investigating both exposures. The outcomes of interest were MI (10 studies), acute coronary syndrome (1 study), and SCD (3 studies). Episodic physical and sexual activity were associated with an increase in the risk of MI (RR = 3.45; 95% confidence interval [CI], 2.33-5.13, and RR = 2.70; 95% CI, 1.48-4.91, respectively). Episodic physical activity was associated with SCD (RR = 4.98; 95% CI, 1.47-16.91). The effect of triggers on the absolute rate of events was limited because exposure to physical and sexual activity is infrequent and their effect is transient; the absolute risk increase associated with 1 hour of additional physical or sexual activity per week was estimated as 2 to 3 per 10,000 person-years for MI and 1 per 10,000 person-years for SCD. Habitual activity levels significantly affected the association of episodic physical activity and MI (P < .001), episodic physical activity and SCD (P < .001), and sexual activity and MI (P = .04); in all cases, individuals with lower habitual activity levels had an increased RR for the triggering effect. For every additional time per week an individual was habitually exposed to physical activity, the RR for MI decreased by approximately 45%, and the RR for SCD decreased by 30%.
  
  
  CONCLUSIONS
  Acute cardiac events were significantly associated with episodic physical and sexual activity; this association was attenuated among persons with high levels of habitual physical activity.
authors.affiliation: Center for Clinical Evidence Synthesis, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, 800 Washington St, Box 63, Boston, MA 02111, USA. idahabreh@tuftsmedicalcenter.org
authors.forename: Issa J
authors.initials: IJ
authors.lastname: Dahabreh
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Paulus
mesh_terms: D054058:Acute Coronary Syndrome / Q000453:epidemiology / Q000209:etiology; D016022:Case-Control Studies; D003075:Coitus; D018592:Cross-Over Studies; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000209:etiology; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology; D012306:Risk