The comparison of principal component analysis ratio with QT dispersion and T-wave alternans in patients with old myocardial infarction

Authors:
A. Kurita, T. Matsui¹, K. Hagisawa, B. Takase², T. Ishizuka, K. Satomura², Biomedical Engineering - Tokorozawa - Japan, ¹National Defense Medical College - Tokorozawa - Japan, ²National Defense Medical College - Tokorozawa - Japan,

Topic(s):
Electrocardiography
Progression / regression coronary artery disease

Background: PCA ratio was a significant univariate predictor of cardiovascular mortality in both men and women, whereas QTd significantly predicted cardiovascular death in women only. Increased QT interval dispersion (QTd) is a proposed ECG marker of vulnerability to ventricular arrhythmias and of cardiovascular (CV) mortality. However, principal component analysis (PCA) of the T-wave vector loop may more accurately represent repolarization abnormalities than QTd. Principal-component-analysis-ratio(PCAr) has been reported as new ventricular heterogeneity-marker. Relation of PCAr with QT-dispersion(QTd) and T-wave-alternans(TWA) is unclear.

Methods: In patients(pts) with old myocardial infarction (OMI,66 ± 8yrs,M/F=14/11), surface-ECG was recorded by Standard 12-lead ECGs were recorded with digital holter recorder. QT interval measurements were performed using interactive software (QT-Guard, GE Medical Systems) that detects QRS onset and uses a least-squares fitting method to identify T-wave offset from the intersection of the maximal slope of the terminal T wave with a threshold defined by the T-P segment.

Results: There were no significant clinical-characteristics-differences between TWA positive(+,n=13) and negative(-,n=12) groups. The PCAr of TWA+group was significantly higher than that of TWA-group(32 ± 19 vs 25 ± 10%, p<0.05). QTd in TWA+ group was significantly higher than that of TWA- group (49 ± 36vs26 ± 9ms,p<0.05).The PCAr correlated with TWA micro voltage (r=0.35, p<0.05) but there was no significant correlation between QTd and TWA-micro-voltage.

Conclusions: PCAr represented ventricular heterogeneity more strongly than QTd, because it correlated with TWA micro voltage better than QTd. PCAr might be useful marker to predict malignant arrhythmia in OMI pts.