title: Long-term recording of cardiac arrhythmias with an implantable cardiac monitor in patients with reduced ejection fraction after acute myocardial infarction: the Cardiac Arrhythmias and Risk Stratification After Acute Myocardial Infarction (CARISMA) study.
abstract: BACKGROUND
  Knowledge about the incidence of cardiac arrhythmias after acute myocardial infarction has been limited by the lack of traditional ECG recording systems to document and confirm asymptomatic and symptomatic arrhythmias. The Cardiac Arrhythmias and Risk Stratification After Myocardial Infarction (CARISMA) trial was designed to study the incidence and prognostic significance of arrhythmias documented by an implantable cardiac monitor among patients with acute myocardial infarction and reduced left ventricular ejection fraction.
  
  
  RESULTS
  A total of 1393 of 5869 patients (24%) screened in the acute phase (3 to 21 days) of an acute myocardial infarction had left ventricular ejection fraction ≤40%. After exclusions, 297 patients (21%) (mean±SD age, 64.0±11.0 years; left ventricular ejection fraction, 31±7%) received an implantable cardiac monitor within 11±5 days of the acute myocardial infarction and were followed up every 3 months for an average of 1.9±0.5 years. Predefined bradyarrhythmias and tachyarrhythmias were recorded in 137 patients (46%); 86% of these were asymptomatic. The implantable cardiac monitor documented a 28% incidence of new-onset atrial fibrillation with fast ventricular response (≥125 bpm), a 13% incidence of nonsustained ventricular tachycardia (≥16 beats), a 10% incidence of high-degree atrioventricular block (≤30 bpm lasting ≥8 seconds), a 7% incidence of sinus bradycardia (≤30 bpm lasting ≥8 seconds), a 5% incidence of sinus arrest (≥5 seconds), a 3% incidence of sustained ventricular tachycardia, and a 3% incidence of ventricular fibrillation. Cox regression analysis with time-dependent covariates revealed that high-degree atrioventricular block was the most powerful predictor of cardiac death (hazard ratio, 6.75; 95% confidence interval, 2.55 to 17.84; P<0.001).
  
  
  CONCLUSIONS
  This is the first study to report on long-term cardiac arrhythmias recorded by an implantable loop recorder in patients with left ventricular ejection fraction ≤40% after myocardial infarction. Clinically significant bradyarrhythmias and tachyarrhythmias were documented in a substantial proportion of patients with depressed left ventricular ejection fraction after acute myocardial infarction. Intermittent high-degree atrioventricular block was associated with a very high risk of cardiac death. Clinical Trial Registration- URL: http://www.ClinicalTrials.gov, Unique identifier: NCT00145119.
authors.affiliation: Department of Cardiology, Gentofte University Hospital, Niels Andersens Vej 65, 2900 Hellerup, Copenhagen, Denmark. pebt@geh.regionh.dk
authors.forename: Poul Erik
authors.initials: PE
authors.lastname: Bloch Thomsen
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
authors.forename: M J Pekka
authors.initials: MJ
authors.lastname: Raatikainen
authors.forename: Rikke
authors.initials: R
authors.lastname: Moerch Joergensen
authors.forename: Juha
authors.initials: J
authors.lastname: Hartikainen
authors.forename: Vesa
authors.initials: V
authors.lastname: Virtanen
authors.forename: J
authors.initials: J
authors.lastname: Boland
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
authors.forename: Uffe Jakob
authors.initials: UJ
authors.lastname: Gang
authors.forename: Nis
authors.initials: N
authors.lastname: Hoest
authors.forename: Lucas V A
authors.initials: LV
authors.lastname: Boersma
authors.forename: Eivin S
authors.initials: ES
authors.lastname: Platou
authors.forename: Daniel
authors.initials: D
authors.lastname: Becker
authors.forename: Marc D
authors.initials: MD
authors.lastname: Messier
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000208:Acute Disease; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D004198:Disease Susceptibility; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000628:therapy; D011379:Prognosis; D018570:Risk Assessment; D013997:Time Factors; D016277:Ventricular Function, Left