On line ST-segment analysis for detection of myocardial ischaemia during and after coronary revascularization
D M Ansley1, J P O'Connor, P M Merrick
1Department of Anaesthesia, Vancouver Hospital and Health Sciences Centre, University of British Columbia, Canada.
Insights
The Marquette ECG monitor shows good accuracy for detecting perioperative myocardial ischemia (PMI) but has notable false negative and false positive rates, especially post-surgery.
Area of Science:
- Cardiology
- Medical Monitoring
- Critical Care Medicine
Background:
- Limited data validates ECG monitoring accuracy in operating rooms and ICUs.
- Perioperative myocardial ischemia (PMI) is a critical concern in high-risk surgical patients.
Purpose of the Study:
- To assess the accuracy, sensitivity, specificity, and predictive values of the Marquette ECG monitor for detecting PMI.
- To evaluate ST segment changes for perioperative myocardial ischemia detection in a high-risk surgical population.
Main Methods:
- Compared Marquette Series 7000 ECG monitor lead V5 with ambulatory continuous electrocardiography (ACECG) lead V5 as the gold standard.
- Evaluated diagnostic test criteria: concordance, sensitivity, specificity, predictive values, and false rates.
- Assessed agreement beyond chance using the Kappa statistic in 28 patients undergoing aortocoronary bypass surgery.
Main Results:
- 83% concordance between Marquette and ACECG monitors.
- Marquette monitor showed a sensitivity of 0.74 and specificity of 0.92.
- False negative rate was 26% and false positive rate was 7.7%, with higher discordance in the postoperative period.
Conclusions:
- Marquette Series 7000 system offers good diagnostic accuracy and high specificity for ST segment analysis.
- Moderate sensitivity and clinically significant false negative/positive rates necessitate caution, particularly postoperatively.
- Further validation of ECG monitoring for perioperative myocardial ischemia is crucial.
Purpose:
A paucity of information exists to validate the accuracy and reliability of ECG monitoring in the operating room or ICU. The purpose of this study was to determine the accuracy, sensitivity, specificity, and predictive values of the Marquette ECG monitor for detection of perioperative myocardial ischaemia (PMI) as measured by ST segment changes in a high risk population.
Methods:
Monitoring for PMI in 28 patients scheduled for aortocoronary bypass surgery was done with the Cardiodata PR ambulatory continuous electrocardiography (ACECG) monitor lead V5, and compared with lead V5 of the Marquette Series 7000 ECG/Surgical operating room monitor, and ECG/Resp ICU monitor. The Marquette lead V5 was evaluated using current criteria for the assessment of diagnostic tests including concordance, sensitivity, specificity, positive and negative predictive values, false positive and false negative rates and compared with the ACECG monitor which served as the reference or "gold standard." Agreement beyond chance between the two methods was assessed using the Kappa statistic.
Results:
Of the 53 observation data points, 27 were defined as ischaemic episodes by ACECG. Concordance between lead V5 in each system was 83% (44/53 episodes). Discordance was 17% (9/53 episodes), predominantly in the postbypass interval (77%, 7/9; P = 0.0184). The incidences of false negatives and false positives for Marquette lead V5 was 26% (7/27) and 7.7% (2/26), respectively. The sensitivity and specificity of the Marquette was 0.74 and 0.92. Positive predictive value was 0.91, negative predictive value was 0.77, and Kappa statistic was 66%.
Conclusion:
Automated ST segment analysis with the Marquette Series 7000 monitoring system demonstrates good diagnostic accuracy, moderate sensitivity, and high specificity. However, clinically significant false negative and false positive rates of ischaemia detection are associated with its use, especially in the postoperative period.
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