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. 2018 Mar-Apr;51(2):288-295.
doi: 10.1016/j.jelectrocard.2017.10.005. Epub 2017 Oct 24.

Evaluation of ECG algorithms designed to improve detect of transient myocardial ischemia to minimize false alarms in patients with suspected acute coronary syndrome

Michele M Pelter  1 , Yuan Xu  2 , Richard Fidler  2 , Ran Xiao  2 , David W Mortara  2 , Hu Xiao  2
Affiliations

Evaluation of ECG algorithms designed to improve detect of transient myocardial ischemia to minimize false alarms in patients with suspected acute coronary syndrome

Michele M Pelter et al. J Electrocardiol. 2018 Mar-Apr.

Abstract

Background: Patients hospitalized for suspected acute coronary syndrome (ACS) are at risk for transient myocardial ischemia. During the "rule-out" phase, continuous ECG ST-segment monitoring can identify transient myocardial ischemia, even when asymptomatic. However, current ST-segment monitoring software is vastly underutilized due to false positive alarms, with resultant alarm fatigue. Current ST algorithms may contribute to alarm fatigue because; (1) they are not designed with a delay (minutes), rather alarm to brief spikes (i.e., turning, heart rate changes), and (2) alarm to changes in a single ECG lead, rather than contiguous leads.

Purpose: This study was designed to determine sensitivity, and specificity, of ST algorithms when accounting for; ST magnitude (100μV vs 200μV), duration, and changes in contiguous ECG leads (i.e., aVL, I, - aVR, II, aVF, III; V1, V2, V3, V4, V5, V6, V6, I).

Methods: This was a secondary analysis from the COMPARE Study, which assessed occurrence rates for transient myocardial ischemia in hospitalized patients with suspected ACS using 12-lead Holter. Transient myocardial ischemia was identified from Holter using >100μV ST-segment ↑ or ↓, in >1 ECG lead, >1min. Algorithms tested against Holter transient myocardial ischemia were done using the University of California San Francisco (UCSF) ECG algorithm and included: (1)100μV vs 200μV any lead during a 5-min ST average; (2)100μV vs 200μV any lead >5min, (3) 100μV vs 200μV any lead during a 5-min ST average in contiguous leads, and (4) 100μV vs 200μV>5min in contiguous leads (Table below).

Results: In 361 patients; mean age 63+12years, 63% male, 56% prior CAD, 43 (11%) had transient myocardial ischemia. Of the 43 patients with transient myocardial ischemia, 17 (40%) had ST-segment elevation events, and 26 (60%) ST-segment depression events. A higher proportion of patients with ST segment depression has missed ischemic events. Table shows sensitivity and specificity for the four algorithms tested.

Conclusions: Sensitivity was highly variable, due to the ST threshold selected, with the 100μV measurement point being superior to the 200μV amplitude threshold. Of all the algorithms tested, there was moderate sensitivity and specificity (70% and 68%) using the 100μV ST-segment threshold, integrated ST-segment changes in contiguous leads during a 5-min average.

Keywords: Acute Coronary Syndrome; Algorithm Development; Hospital ECG Monitoring; Myocardial Ischemia; ST Monitoring.

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Conflict of interest statement

Conflicts of interest: none

Figures

Figure 1
Figure 1
Shows 17 patients with ST-segment elevation events (blue bar) and number of patients missed by each of the four algorithms using ST amplitude of 100 μV (orange) versus 200 μV (grey). [Table: see text]
Figure 2
Figure 2
Shown are the six precordial leads (V1 to V6) in a missed ST-segment elevation event when using the 200 μV amplitude threshold. The panel on the left is the baseline ST-segment level in a 55-year-old male admitted with chest pain rule out acute coronary syndrome. The middle panel shows maximal ST-segment elevation during the event, note ST-segment elevation in leads V1 to V3, which does not exceed the 200 μV threshold. T-wave changes are seen in leads V4 to V6. The panel on the right shows the return of the ST-segments to the level prior to the elevation event.
Figure 3
Figure 3
Shows 26 patients with ST-segment depression events (blue bar) and number of patients missed by each of the four algorithms using ST amplitude of 100 μV (orange) versus 200 μV (grey). [Table: see text]
Figure 4
Figure 4
Shown are two 12-lead ECG’s in a missed ST-segment depression event. The panel on the left is a baseline 12-lead ECG in a 78-year-old male admitted with chest pain rule out acute coronary syndrome. The 12-lead ECG on the right shows an ST-segment depression event, note increased heart rate and ST-segment depression in multiple ECG leads. This event was missed by all tested algorithms since the ST-segment depression only reached −91 μV, and not the −100 μV criteria used in the primary study.
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