title: Clinical and electrophysiological spectrum of idiopathic ventricular outflow tract arrhythmias.
abstract: OBJECTIVE
  This study sought to compare and contrast the clinical and electrophysiological characteristics of outflow tract arrhythmias.
  
  
  BACKGROUND
  Idiopathic ventricular outflow tract arrhythmias manifest clinically in 3 forms: 1) paroxysmal sustained monomorphic ventricular tachycardia (SMVT), 2) repetitive nonsustained ventricular tachycardia (NSVT), or 3) premature ventricular contractions (PVCs). Although these arrhythmias have a similar site of origin, it is unknown whether they share a common mechanism or similar clinical features.
  
  
  METHODS
  A total of 127 patients (63 female [50%], mean age 51 +/- 15 years) were evaluated for outflow tract arrhythmias.
  
  
  RESULTS
  A total of 36 (28%) presented with the index clinical arrhythmia of SMVT, 46 (36%) with NSVT, and 45 (35%) with PVCs. The sites of origin of the arrhythmias were similar among the 3 groups, occurring in the right ventricular outflow tract in 82%. Sustained ventricular tachycardia was more likely to be induced during exercise in the SMVT (10 of 15 patients [67%]) than NSVT or PVCs groups (p < 0.01). Sustained outflow tract ventricular tachycardia was induced at electrophysiology study in 78% of SMVT patients, 48% of NSVT patients, and 4% of PVCs patients. Adenosine was similarly effective in all 3 groups (p = NS).
  
  
  CONCLUSIONS
  Patients with outflow tract arrhythmias can be differentiated based on the subtype of arrhythmia. However, the observation that approximately 50% of patients with NSVT and approximately 5% of patients with PVCs have inducible sustained ventricular tachycardia that behaves in an identically unique manner to those who present with sustained ventricular tachycardia (e.g., adenosine-sensitive) suggests that rather than representing distinct entities, outflow arrhythmias may be considered a continuum of a single mechanism.
authors.affiliation: Department of Medicine, Division of Cardiology, Cornell University Medical Center, New York, New York 10021, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kim
authors.forename: Sei
authors.initials: S
authors.lastname: Iwai
authors.forename: Steven M
authors.initials: SM
authors.lastname: Markowitz
authors.forename: Bindi K
authors.initials: BK
authors.lastname: Shah
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Stein
authors.forename: Bruce B
authors.initials: BB
authors.lastname: Lerman
mesh_terms: D000241:Adenosine / Q000627:therapeutic use; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D002648:Child; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000503:physiopathology*; D018879:Ventricular Premature Complexes / Q000503:physiopathology*; D014700:Verapamil / Q000627:therapeutic use
chemical_list: D000889:Anti-Arrhythmia Agents; D014700:Verapamil; D000241:Adenosine