Should ST elevation be measured at the J point or 60 ms later?
Date First Published:
March 11, 2015
Last Updated:
March 11, 2015
Report by:
Niall Morris, Clinical Research Fellow (Central Manchester University Hospitals NHS Foundation Trust, The University of Manchester. UK)
Search checked by:
Ben Harris, Central Manchester University Hospitals NHS Foundation Trust, The University of Manchester. UK
Three-Part Question:
In [patients with suspected acute coronary syndromes in the ED] does [measuring ST segment elevation at the J point or 60 ms after the J point] enable [more accurate diagnosis of acute coronary occlusion]?
Clinical Scenario:
A patient presents to the emergency department (ED) with a suspected acute coronary syndrome. The ECG shows ST elevation, which almost meets the criteria for the diagnosis of ST elevation myocardial infarction (STEMI) when measured at the J point. If measured 60 ms after the J point, the ECG meets criteria for diagnosing STEMI. You wonder if there is any evidence to determine whether ST elevation should be measured at the J point, as stipulated in international guidance (Thygesen et al, 2012), or 60 ms after the J point)
Search Strategy:
We searched the following databases using the Ovid interface: EBM Reviews—Cochrane Database of Systematic Reviews 2005 to August 2014, EBM Reviews—ACP Journal Club 1991 to September 2014, EBM Reviews—Database of Abstracts of Reviews of Effects 3rd Quarter 2014, Ovid MEDLINE(R) 1946 to September Week 4 2014, Embase 1974 to 2014 Week 40
Search Details:
[ST segment.mp. OR STEMI.mp. OR exp ST segment elevation myocardial infarction/ OR exp ST segment/] or [Percutaneous Coronary Intervention.mp. OR PCI.mp. OR exp Percutaneous Coronary intervention/] AND [60 ms.mp. OR 60 milliseconds.mp.]
Outcome:
We identified a total of 155 papers. After removal of duplicates, 96 papers remained. Following review, there were three papers that related to the three-part question
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| ST elevation measurements differ in patients with inferior myocardial infarction and right ventricular infarction. Seo D-W, Sohn CH, Ryu JM, et al. 2011, South Korea | Patients presenting to the ED. Cohort of those identified as having inferior myocardial infarction on angiography (LCx or RCA occlusion). 88 patients who were initially diagnosed as STEMI and received immediate PCI as per protocol. 109 patients with NSTEMI picture who received PCI after cardiac enzyme rise | Retrospective cohort | Culprit lesion identified by interventional cardiologist. | STE group culprit lesion: 76 RCA, 11, LCx, 1 RCA and LCx<br><br>NSTEMI group culprit lesion; 77 RCA, 26 LCx, 6 RCA and LCx | No data on whether occlusion was critical (>70%) or not. No effort made to ensure reliability of angiography findings. Retrospective. Selection bias. p Values are large. Only looks at inferior myocardial infarctions, so no review of precordial leads |
| STE change at J point and 60 ms after. STE defined by two investigators blinded to angiography and clinical data Rater 1 | J point - STE group n=81 (92%). 60 ms n=85 (97%) p= 0.165<br><br> Control group - J point n=8 (7%). 60 mins n=11 (10%) p=0.315 | ||||
| STE change at J point and 60 ms after. STE defined by two investigators blinded to angiography and clinical data Rater 2 | J point - STE group n=78 (89%). 60 ms n=83 p=0.14<br><br>Control group - J point n=6 (6%). 60 ms n=n=8 (7%) p=0.392 | ||||
| 371 Performance of ST-Elevation Criteria for Anterior STEMI, and Comparison With a Decision Rule for Differentiation From Early Repolarization. Smith SW, Scharrer E, Khalil A, et al. 2011, USA | ECGs of consecutive patients undergoing coronary intervention for proven acute LAD occlusion, and a control group of consecutive ED non-cardiac chest pain patients (three negative troponins) with ECGs coded as early repolarisation | Retrospective cohort study at two tertiary centres | Sensitivity and specificity for LAD occlusion using four criteria J point | 2 mm in V1–V3 or 1 mm in V4–V6 Sn 61, Sp 55<br><br> 1 mm in V1 and V4–V6 or 2 mm V2–V3 (male)/1.5 mm V2–V3 (female) Sn 67, Sp 47<br><br>1 mm in V1, V4–V6 or 2 mm V2–V3 (male), 2.5 mm V2–V3 (male <40 years old), 1.5 mm V2–V3 (female) Sn 67, Sp 54<br><br>1 mm V5–V6 or 2 mm V1–V4 Sn 57, Sp 66 | Conference presentation so abstract only. No detail in abstract relating to inter-observer reliability |
| Sensitivity and specificity for LAD occlusion using four criteria 60 min post J point | 2 mm in V1–V3 or 1 mm in V4–V6 Sn 83, Sp 29<br><br>1 mm in V1 and V4–V6 or 2 mm V2–V3 (male)/1.5 mm V2–V3 (female) Sn 92, Sp 18 <br><br>1 mm in V1, V4–V6 or 2 mm V2–V3 (male), 2.5 mm V2–V3 (male <40 years old), 1.5 mm V2–V3 (female) Sn 92, Sp 25<br><br>1 mm V5–V6 or 2 mm V1–V4 Sn 80, Sp 36 | ||||
| Then illustrated how Smith's own decision rule performs at differentiating LAD occlusion from early repolarisation) | Sn 86, Sp 91 (decision rule is measured at 60 ms | ||||
| ST segment elevation differs depending on the method of measurement. Smith SW. 2006, USA | 159 patients coded as anterior MI. 51 admitted through ED for primary PCI. 37 met inclusion criteria | Retrospective cohort study of the 37 patients | Number of patients who had STE Rater 1 | 1 mm STE in two consecutive leads -J point 32 (86%). 60 ms after 36 (97% p=0.10<br><br>2 mm STE in two consecutive leads - J point 22 (59%). 60 mins after 30 (81%) p=0.04<br><br>ST score >6 mm in V1-6 -J point 26 (70%). 60 mins after 33 (89%) p=0.04 | Retrospective study that focused on anterior MIs only. Small cohort. Selection bias relying on correct coding; there may have been patients who were not labelled as anterior MI who this study missed |
| Number of patients who had STE Rater 2 | 1 mm STE in two consecutive leads - J point 32 (86%). 60 mins after 36 (97%) p=0.10<br><br>2 mm STE in two consecutive leads - J point 25 (68%). 60 mins 30 (81%) p=0.14<br><br>ST score >6 mm in V1–V6 - J point 26 (70%). 60 mins after 32 (86%) p=0.08 |
Author Commentary:
As one would expect, ST elevation measurements change depending where the measurement is taken from. There is limited evidence that measuring STE further away from the J point can improve sensitivity while specificity drops. There is no evidence, however, that such a move would reduce mortality if these patients were offered immediate revascularisation, for example. Further research in this area is warranted.
Bottom Line:
With the current evidence, measurement of ST elevation at a different location to the J point cannot be advocated.
References:
- Thygesen K, Alpert JS, Jaffe AS, et al.. Third universal definition of myocardial infarction.
- Seo D-W, Sohn CH, Ryu JM, et al.. ST elevation measurements differ in patients with inferior myocardial infarction and right ventricular infarction.
- Smith SW, Scharrer E, Khalil A, et al.. 371 Performance of ST-Elevation Criteria for Anterior STEMI, and Comparison With a Decision Rule for Differentiation From Early Repolarization.
- Smith SW.. ST segment elevation differs depending on the method of measurement.