Spatial indices of repolarization correlate with non-ST elevation myocardial ischemia in patients with chest pain

  • Salah Al-Zaiti
  • Ervin Sejdić
  • Jan Nemec
  • Clifton Callaway
  • Prem Soman
  • Robert Lux
Original Article


Mild-to-moderate ischemia does not result in ST segment elevation on the electrocardiogram (ECG), but rather non-specific changes in the T wave, which are frequently labeled as non-diagnostic for ischemia. Robust methods to quantify such T wave heterogeneity can have immediate clinical applications. We sought to evaluate the effects of spontaneous ischemia on the evolution of spatial T wave changes, based on the eigenvalues of the spatial correlation matrix of the ECG, in patients undergoing nuclear cardiac imaging for evaluating intermittent chest pain. We computed T wave complexity (TWC), the ratio of the second to the first eigenvalue of repolarization, from 5-min baseline and 5-min peak-stress Holter ECG recordings. Our sample included 30 males and 20 females aged 63 ± 11 years. Compared to baseline, significant changes in TWC were only seen in patients with ischemia (n = 10) during stress testing, but not among others. The absolute changes in TWC were significantly larger in the ischemia group compared to others, with a pattern that seemed to depend on the severity or anatomic distribution of ischemia. Our results demonstrate that ischemia-induced changes in T wave morphology can be meaningfully quantified from the surface 12-lead ECG, suggesting an important opportunity for improving diagnostics in patients with chest pain.


Ischemia Ventricular repolarization dispersion T wave Electrocardiogram 



Acute myocardial infarction


Action potential


Coronary artery disease




Left anterior descending coronary artery


Left circumflex coronary artery


Principal component analysis


Percutaneous coronary intervention


Right coronary artery


Receiver operator characteristics curve


Changes in T wave complexity relative to baseline variations


Single-photon emission computed tomography


Standard deviation of normal-to-normal R-R interval


T wave complexity


Ventricular repolarization dispersion


Compliance of ethical standards


Funding was provided by the Central Research development Grant from University of Pittsburgh (PI Al-Zaiti).

Conflict of interest

The authors declare that they have no competing interests.


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Copyright information

© International Federation for Medical and Biological Engineering 2017

Authors and Affiliations

  • Salah Al-Zaiti
    • 1
    • 2
  • Ervin Sejdić
    • 3
  • Jan Nemec
    • 4
  • Clifton Callaway
    • 2
  • Prem Soman
    • 5
  • Robert Lux
    • 6
  1. 1.Department of Acute & Tertiary Care Nursing, School of NursingUniversity of PittsburghPittsburghUSA
  2. 2.Department of Emergency MedicineUniversity of PittsburghPittsburghUSA
  3. 3.Department of Computer & Electrical EngineeringUniversity of PittsburghPittsburghUSA
  4. 4.Department of Cardiac ElectrophysiologyUniversity of PittsburghPittsburghUSA
  5. 5.Department of Nuclear CardiologyUniversity of PittsburghPittsburgh,USA
  6. 6.Department of Cardiovascular MedicineUniversity of UtahSalt LakeUSA

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