title: Summer syncope syndrome.
abstract: BACKGROUND
  Antihypertensive therapy is associated with significant relative risk reductions in the incidence of heart failure, myocardial infarction, and stroke. However, a common adverse reaction to antihypertensive therapy is orthostatic hypotension, dehydration, and syncope. We propose that continued use of antihypertensive medications at the same dosage during the dry summer months in patients living in the Sonoran desert leads to an increase in syncopal episodes.
  
  
  METHODS
  All hypertensive patients who were treated with medications and admitted with International Classification of Diseases, 9th Revision code diagnosis of syncope were included. They were defined as "cases" if they presented during the summer months (May to September 2012) and "controls" if they presented during the winter months (November 2012 to March 2013). The primary outcome measure was the presence of clinical dehydration. The statistical significance was determined using the 2-sided Fisher exact test.
  
  
  RESULTS
  A total of 496 patients with an International Classification of Diseases, 9th Revision code diagnosis of syncope were screened, and 179 patients were included in the final analysis. In patients taking antihypertensive medications, there were a significantly higher number of cases of syncope secondary to dehydration or orthostatic hypotension during the summer months (45%) compared with the winter months (26%) (P = .01). The incidence of syncope was significantly higher in older patients (63%) compared with younger individuals (37%) during the summer months.
  
  
  CONCLUSIONS
  The incidence of syncope increases during the summer months among people who reside in a dry desert climate and who are taking antihypertensive medications. On the basis of our findings, we describe an easily preventable condition that we define as the "Summer Syncope Syndrome." We recommend judicious reduction of antihypertensive therapy in patients residing in a hot and dry climate, particularly during the summer months.
authors.affiliation: Department of Internal Medicine, Arizona College of Medicine at South Campus, University of Arizona, Tucson.
authors.forename: Jennifer Juxiang
authors.initials: JJ
authors.lastname: Huang
authors.affiliation: Department of Internal Medicine, Arizona College of Medicine at South Campus, University of Arizona, Tucson.
authors.forename: Natasha
authors.initials: N
authors.lastname: Sharda
authors.affiliation: Department of Internal Medicine, Arizona College of Medicine, University of Arizona, Tucson.
authors.forename: Irbaz Bin
authors.initials: IB
authors.lastname: Riaz
authors.affiliation: Department of Cardiology, Sarver Heart Center, University of Arizona, Tucson. Electronic address: jalpert@shc.arizona.edu.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Alpert
mesh_terms: D000368:Aged; D000375:Aging; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D012621:Seasons; D013575:Syncope / Q000209:etiology*
chemical_list: D000959:Antihypertensive Agents
keywords: Antihypertensive therapy; Desert climate; Summer; Syncope