The comparison of principal component
analysis ratio with QT dispersion and T-wave alternans in patients with old
myocardial infarction |
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Topic(s): |
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. |