[Role of spectral turbulence analysis of ECG in predicting risk of arrhythmia after myocardial infarction].
BACKGROUND
Spectral turbulence analysis (STA) of the signal-averaged electrocardiogram (SAECG) is a recently described frequency-domain analysis evaluating the changes in the wave front velocity in the QRS complex as a whole. In this study we prospectively assessed the role of STA in predicting arrhythmic events [(EA): ventricular tachycardia, ventricular fibrillation and sudden death] relative to ejection fraction (EF), complex ventricular arrhythmias (CVA) on Holter monitoring and site of myocardial infarction (MI) in 266 patients (pts) (209 M; 57 F; mean age 62.3 +/- 10.3)-14 with bundle branch block-surviving an acute MI.


METHODS
SAECG was recorded in all pts 13 +/- 3 days after MI. STA was performed by using a PC software implementing the algorithm proposed by Kelen. The conventional parameters of STA (inter-slice correlation mean, inter-slice correlation SD, low-slice correlation ratio and spectral entropy) were calculated separately for each orthogonal lead (X, Y and Z) and their average (X + Y + Z). Ejection fraction was assessed in 241 pts and Holter recordings were analyzed in 195 pts 13 +/- 4 and 13 +/- 5 days after MI, respectively.


RESULTS
During a mean follow-up of 13 +/- 10 months, there were 20 (7.5%) AE: 9 pts had sustained ventricular tachycardia, two had cardiac arrest due to ventricular fibrillation and 9 died suddenly. In 41% of pts STA was abnormal. STA sensitivity was 65%, specificity 61%, positive predictive value 12%, negative predictive value 96%, relative risk (RR) 2.67 (95% confidence bounds = 1.1-6.48; p = 0.023). Sensitivity, specificity, positive predictive value and RR for EF and CVA were 65, 78, 21%, 6.5 and 64, 66, 10%, 3.4, respectively. Abnormal STA was present in 46% of pts with anterior MI and in 42% of pts with inferior MI (ns). Sensitivity, specificity and RR were 88, 58% and 7.95 (p = 0.015) for anterior MI and 50, 59% and 1.41 (p = ns) for inferior MI.


CONCLUSIONS
The value of STA of the SAECG is poor when performed two weeks after MI. STA theoretical advantages over time-domain analysis of the SAECG were not verified in our study.
Vado
A
A
Divisione di Cardiologia, Azienda Ospedaliera S. Croce, Cuneo.
Bruna
C
C
Rossetti
G
G
Isoardi
D
D
Cherasco
E
E
Borello
W
W
Uslenghi
E
E
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000517:prevention & control; D002037:Bundle-Branch Block / Q000209:etiology / Q000517:prevention & control; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D011379:Prognosis; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000517:prevention & control; D014693:Ventricular Fibrillation / Q000209:etiology / Q000517:prevention & control