The electrocardiogram (ECG) criteria for acute coronary syndrome (ACS) were found to have very low diagnostic accuracy in patients presenting to the emergency department (ED) with chest pain, according to a study published in the Journal of Electrocardiology.

Despite current guidelines, there is little evidence to support the use of ST deviation at the J point (STJ) on ECGs as the optimal point for ST amplitude measurement for the detection of ACS.

In this Swedish register-based cohort study, data from the Evaluation of Unknown Predictors of Electrocardiographic Changes – a Transnational study (EXPECT) database, collected between 2010 and 2014, were examined. In this study conducted at a single center, 14,148 unselected patients who presented to the ED with chest pain aged >18 years (mean age, 55.6 years; 47.4% women) were included. All patients underwent an ECG on arrival at the ED, and ST deviation amplitude was measured at STJ and at 20, 40, 60, and 80 milliseconds after STJ (ST20, ST40, ST60, and ST80, respectively).

The study’s primary outcome was the presence/absence of a discharge diagnosis of ACS at the index ED visit. The investigators calculated the sensitivity, specificity, negative predictive value (NPV), a positive predictive value (PPV), and positive and negative likelihood ratios (LR+ and LR-, respectively) of ACS at the index visit at each time point of ST amplitude measurement.

A total of 1489 patients (10.5%; mean age, 68.1 years; 31.1% women) had discharge diagnoses of ACS. All-cause 30-day mortality was 0.8% (n=109), including 32 patients (29%) diagnosed with ACS.

At STJ and ST20, the ECG criteria for ACS had sensitivities of 28.4% and 31.4%, respectively; specificities of 91.8% and 90.0%, respectively; NPVs of 91.6% and 91.8%, respectively; PPVs of 28.8% and 27%, respectively; LR+ of 3.4% and 3.2, respectively; and LR- of 0.8 for both. In both sexes, moving away from STJ, this trend continued at the other time points, with sensitivities increasing and specificities decreasing. The ECG criteria in women vs men had greater sensitivity (32.0% vs 26.8%, respectively) and specificity (92.4% vs 91.1%, respectively) for ACS.

Although the optimal measuring point varied with age, sex, and deviation type, the optimal points for detecting ACS were STJ and ST20, and the highest NPVs and PPVs for ACS were observed when points close to the J point were used.

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Study limitations include a reliance on hospital records for diagnoses, a lack of angiography data, the analysis of single vs serial ECGs, and the inclusion of all chest pain types.

“The small theoretical advantage of using different measuring points must be weighed against the benefit of a single uniform way of measuring ST amplitude in all patients,” noted the authors.

Funding

UE and JLF have received funding from the Region Skåne, from Swedish ALF grants, and from the Swedish Heart-Lung foundation for this study. PP has received funding from the Swedish Heart-Lung Foundation. ATL is funded by an unrestricted grant from the philanthropic fund TRYG-Foundation given to University of Southern Denmark.

Reference

Lindow T, Wiiala J, Forberg JL, et al. Optimal measuring point for ST deviation in chest pain patients with possible acute coronary syndrome. J Electrocardiol. 2020;58:165-170. doi:10.1016/j.jelectrocard.2019.12.012