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Updated: Aug 17, 2026

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
18:11

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

Published on: December 28, 2012

ST-segment deviations during pacing-induced increased heart rate in patients without coronary artery disease

Sören Häggmark1, Michael F Haney, Steen M Jensen

  • 1Cardiothoracic Surgery, Heart Centre, University Hospital, Umeå, Sweden. soren.haggmark@vll.se

Clinical Physiology and Functional Imaging
|June 24, 2005
PubMed

Insights

The relative ST change vector magnitude (STC-VM) increases linearly with heart rates above 100 bpm, potentially exceeding ischemia thresholds without actual ischemia. This finding is crucial for accurately interpreting ECGs in patients with elevated heart rates.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Diagnostic ECG

Background:

  • Interpreting ST-segment changes for ischemia requires understanding their relationship with heart rate (HR) in healthy individuals.
  • Defining this relationship is crucial for accurate ischemia detection, especially at higher HRs.

Purpose of the Study:

  • To define the relationship between ST-segment levels and HR in subjects without coronary artery disease.
  • To assess how ST-vector magnitude (ST-VM) and relative ST change vector magnitude (STC-VM) change with increasing HR.

Main Methods:

  • Eighteen patients with normal ECGs underwent computerized online vectorcardiography (VCG) during atrial pacing.
  • HR was increased stepwise up to 150 bpm.
  • STC-VM and ST-VM were analyzed at J point, J + 20 ms, and J + 60 ms.

Main Results:

  • STC-VM increased progressively with HR above 100 bpm (15-20 microV per 10 bpm increase).
  • ST-VM showed a heterogeneous and unpredictable pattern during HR increases.
  • No significant difference in STC-VM or ST-VM trends was observed based on the J point measurement timing (0, 20, or 60 ms).

Conclusions:

  • STC-VM exhibits a linear increase with rising HRs above 100 bpm.
  • Elevated STC-VM values at higher HRs may surpass established ischemia thresholds in the absence of actual ischemia.
  • Further clinical studies are necessary to enhance the diagnostic specificity of STC-VM measurements during elevated HRs.
Abstract

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