title: Outcome of patients with hypertrophic cardiomyopathy and a normal electrocardiogram.
abstract: OBJECTIVE
  This study sought to clarify the frequency, clinical phenotype, and prognosis of those patients with hypertrophic cardiomyopathy (HCM) who present with a normal electrocardiogram (ECG).
  
  
  BACKGROUND
  Hypertrophic cardiomyopathy is the most common cause of sudden death in young people. Screening advocates have recommended a 12-lead ECG for the early detection of HCM in athletes, yet the clinical outcomes of those presenting with a normal ECG remains to be fully delineated.
  
  
  METHODS
  Baseline characteristic and echocardiographic data were collected on all patients with HCM who initially presented to our institution with a diagnostic echocardiogram but a normal ECG. Follow-up was obtained and compared with the prognosis of HCM patients who presented with abnormal ECGs.
  
  
  RESULTS
  We compared 135 HCM patients with a normal ECG with 2,350 HCM patients with an abnormal ECG. The latter group was more likely to have worse symptoms, have higher gradients, and a greater degree of septal wall thickness than the patients with a normal ECG. Severe obstructive symptoms requiring surgical myectomy and implantation of an implantable cardioverter-defibrillator were more common in patients with abnormal ECGs. Cardiac survival was significantly better in the group with a normal ECG at presentation-none of these patients had a cardiac death at follow-up.
  
  
  CONCLUSIONS
  Almost 6% of patients presenting with demonstrable echocardiographic evidence of HCM had a normal ECG at the time of diagnosis. This subset of patients with normal ECG-HCM appears to exhibit a less severe phenotype with better cardiovascular outcomes.
authors: Department of Internal Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors: Christopher J
authors: CJ
authors: McLeod
authors: Michael J
authors: MJ
authors: Ackerman
authors: Rick A
authors: RA
authors: Nishimura
authors: A Jamil
authors: AJ
authors: Tajik
authors: Bernard J
authors: BJ
authors: Gersh
authors: Steve R
authors: SR
authors: Ommen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D002648:Child; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult