title: Seasonal variation of ventricular tachycardia registered in 24-hour Holter monitoring.
abstract: OBJECTIVE
  To evaluate the seasonal variation of ventricular arrhythmias and its correlation with ambient temperature in patients submitted to 24-hour Holter monitoring in the city of Porto Alegre, southern Brazil.
  
  
  METHODS
  Holter monitoring reports of 3,034 patients from 1996 to 2002 were analyzed. Ventricular tachycardia (VT) was defined as the presence of 3 or more consecutive ventricular beats, at a rate equal to or higher than 100 beats per minute. Percentage distribution of patients presenting VT by seasons and its correlation with ambient temperature were analyzed.
  
  
  RESULTS
  Mean age was 59.2 +/- 17.4 years, with a predominance of the female sex (61.9%). Patient distribution by season of the year was: 561 (18.5%) in summer, 756 (24.9%) in fall, 843 (27.8%) in winter and 874 (28.8%) in spring. Fifty-two patients (9.3%) presented VT episodes in summer, 39 (5.2%) in autumn, 56 (6.6%) in winter and 60 (6.9%) in spring (p = 0.035). There was a 40% relative increase in the proportion of patients presenting VT during summer in comparison to winter. There was a trend of increase in the proportion of patients presenting VT with rising temperatures (r = 0.57; p = 0.052).
  
  
  CONCLUSIONS
  The occurrence of VT presents seasonal variations in southern Brazil, with a higher proportion of episodes occurring in summer. There is an association trend between VT and temperature increase.
authors.affiliation: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. mauriciopimentel@cardiol.br
authors.forename: Maurício
authors.initials: M
authors.lastname: Pimentel
authors.forename: Letícia
authors.initials: L
authors.lastname: Grüdtner
authors.forename: Leandro I
authors.initials: LI
authors.lastname: Zimerman
mesh_terms: D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012621:Seasons; D017678:Sex Distribution; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D013696:Temperature