Incremental diagnostic and prognostic value of the QRS-T angle, a 12-lead ECG marker quantifying heterogeneity of depolarization and repolarization, in patients with suspected non-ST-elevation myocardial infarction.

BACKGROUND: The value of the 12-lead ECG in the diagnosis of non-ST-elevation myocardial infarction (NSTEMI) is limited due to insufficient sensitivity and specificity of standard ECG criteria. The QRS-T angle reflects depolarization-repolarization heterogeneity and might assist in detecting patients with a NSTEMI (diagnosis) as well as predicting patients with an increased mortality risk (prognosis). METHODS: We prospectively enrolled 2705 consecutive patients with symptoms suggestive of NSTEMI. The QRS-T angle was automatically derived from the standard 10 s 12-lead ECG recorded at presentation to the ED. Patients were followed up for all-cause mortality for 2 years. RESULTS: NSTEMI was the final diagnosis in 15% (n = 412) of patients. QRS-T angles were significantly greater in patients with NSTEMI compared to those without (p < 0.001). The use of the QRS-T angle in addition to standard ECG criteria indicative of ischemia improved the diagnostic accuracy for NSTEMI as quantified by the area under the ROC curve from 0.68 to 0.72 (p < 0.001). An algorithm for the combined use of standard ECG criteria and the QRS-T angle improved the sensitivity of the ECG for NSTEMI from 45% to 78% and the specificity from 86% to 91% (p < 0.001 for both comparisons). The 2-year survival rates were 98%, 97% and 87% according to QRS-T angle tertiles (p < 0.001). CONCLUSION: In patients with suspected NSTEMI, the QRS-T angle derived from the standard 12-lead ECG provides incremental diagnostic accuracy on top of standard ECG criteria indicative of ischemia, and independently predicts all-cause mortality during 2 years of follow-up.

Diagnostic and prognostic value of QRS duration and QTc interval in patients with suspected myocardial infarction.

BACKGROUND: While prolongation of QRS duration and QTc interval during acute myocardial infarction (AMI) has been reported in animals, limited data is available for these readily available electrocardiography (ECG) markers in humans. METHODS: Diagnostic and prognostic value of QRS duration and QTc interval in patients with suspected AMI in a prospective diagnostic multicentre study were prospectively assessed. Digital 12-lead ECGs were recorded at presentation. QRS duration and QTc interval were automatically calculated in a blinded fashion. Final diagnosis was adjudicated by two independent cardiologists. The prognostic endpoint was all-cause mortality during 24 months of follow-up. RESULTS: Among 4042 patients, AMI was the final diagnosis in 19% of patients. Median QRS duration and median QTc interval were significantly greater in patients with AMI compared to those with other final diagnoses (98 ms [IQR 88-108] vs. 94 ms [IQR 86-102] and 436 ms [IQR 414-462] vs. 425 ms [IQR 407-445], p < 0.001 for both comparisons). The diagnostic value of both ECG signatures however was only modest (AUC 0.56 and 0.60). Cumulative mortality rates after 2 years were 15.9% vs. 5.6% in patients with a QRS > 120 ms compared to a QRS duration ≤ 120 ms (p < 0.001), and 11.4% vs. 4.3% in patients with a QTc > 440 ms compared to a QRS duration ≤ 440 ms (p < 0.001). After adjustment for age and important ECG and clinical parameters, the QTc interval but not QRS duration remained an independent predictor of mortality. CONCLUSIONS: Prolongation of QRS duration > 120 ms and QTc interval > 440 ms predict mortality in patients with suspected AMI, but do not add diagnostic value.