RR-interval irregularity precedes ventricular fibrillation in ST elevation acute myocardial infarction.
BACKGROUND
Sudden cardiac arrest is a leading cause of death in industrialized countries, and ischemic ventricular fibrillation (VF) is a frequent cause.


OBJECTIVE
The purpose of this study was to determine whether patients with ST elevation myocardial infarction (STEMI) who develop ischemic VF show more overall RR-interval irregularity (RRI) than do STEMI patients without ischemic VF.


METHODS
Ischemic VF was identified in 41 patients from 1,473 digital 12-lead Holter recordings from three separate STEMI studies. Continuous 3-lead and 12-lead electrocardiogram (ECG) snapshots recorded every minute were compared between all ischemic VF patients and 123 random patients without ischemic VF. Time intervals from start of Holter to ischemic VF and equivalent intervals in the controls were used for calculations. ECG variables related to conduction intervals and severity of ischemia were measured using the most ischemic 12-lead ECG. RRI was calculated as the square root of the mean squared differences of successive RR intervals. For RRI, all QRS complexes, including ventricular ectopic beats, were used.


RESULTS
No baseline differences were observed between the study and control groups, except for male preponderance among ischemic VF patients (90% vs 72%, P = .019). QRS interval, ECG ischemia severity, RRI, and number of ventricular ectopic beats were significantly associated with ischemic VF. Multivariate analysis revealed RRI (odds ratio 1.006, 95% confidence interval 1.001-1.010, P = .016) and ST deviation score (odds ratio 1.073, 95% confidence interval 1.041-1.106, P <.001) as the only statistically significant predictors of ischemic VF.


CONCLUSIONS
In the period before ischemic VF, RRI and ST deviation score are associated with ischemic VF in STEMI patients. These findings could have important pathophysiologic and clinical implications.
Lemmert
Miguel E
ME
Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands. mlemmert@gmail.com
Majidi
Mohamed
M
Krucoff
Mitchell W
MW
Bekkers
Sebastiaan C A M
SC
Crijns
Harry J G M
HJ
Wellens
Hein J J
HJ
Kosinski
Andrzej S
AS
Gorgels
Anton P M
AP
D000368:Aged; D019540:Area Under Curve; D016001:Confidence Intervals; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology*; D016017:Odds Ratio; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D014693:Ventricular Fibrillation / Q000209:etiology / Q000503:physiopathology*