HRJ: T-wave morphology parameters open new doors to mortality prognosis

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T-wave morphology parameters contain predictive value for mortality in the general population, independent of other clinical risk factors, according to a study in the August edition of the HeartRhythm Journal.  

T-wave morphology parameters measure abnormalities during the ventricular repolarization phase and are potentially interrelated with arrhythmia vulnerability.

Abnormalities of ventricular repolarization on the ECG have been shown to be associated with morbidity and mortality in patients with cardiovascular disease, but evidence that it has prognostic value in the general population is weak, according to the authors. T-wave morphology has been shown to be prognostic in patients with diabetes and end-stage renal disease, but evidence of its prognostic value in the general population also is weak.

The study, led by Kimmo Porthan, MD, from the department of cardiology at Helsinki University Central Hospital in Finland, indicated that T-wave morphology parameters may allow healthcare professionals to better assess arrhythmia vulnerability in patients, and the prognostic value is uniquely related to cardiovascular mortality and seems to be gender specific.

The study was conducted by assessing 5,917 adults participating in the Finnish population-based Health 2000 Study. Of the 335 deaths that occurred between the start of the study and a mean follow-up of nearly six years, 131 were cardiovascular deaths.

Researchers assessed ventricular repolarization using a set of four T-wave morphology parameters:
  • Principal component analysis ratio (PCA ratio, an estimate of T-wave complexity);
  • T-wave morphology dispersion (TMD, an estimate of deviation between T waves);
  • Total cosine R-to-T (TCRT, an estimate of deviation between R and T waves); and
  • T-wave residuum (TWR, an estimate of repolarization heterogeneity).

Subjects who died had longer ECG repolarization duration (QT interval) and higher degree of ECG repolarization heterogeneity than did those who survived. In addition, those who died had further changes in T-wave morphology. T-wave morphology parameters also showed gender specificity in their performance, with PCA ratio and TMD in men as well as TWR in women providing the highest prognostic value.

These results suggest that T-wave morphology parameters should be assessed gender specifically in order for clinical risk indicators to be as precise as possible, the authors concluded.

“The study shows that, unlike ECG QT intervals, T-wave morphology parameters contain predictive value for mortality in the general population,” said Porthan. “The study results deepen our existing knowledge about the predictive value of several ECG repolarization parameters and will potentially help plan future clinical trials assessing cardiac repolarization.”