What is the clinical evidence from this study?

Study design: Observational. Population: chronic coronary syndrome (n=5876). Intervention: Abnormal ECG tracing vs. Normal ECG tracing. Primary outcome: cardiovascular death (aHR 2.01, 95% CI 1.58-2.55).

What does this research mean for the field?

In patients with chronic coronary syndrome, baseline electrocardiogram abnormalities, including repolarization and conduction defects, are independently associated with a twofold increased risk of cardiovascular death. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

September 14, 2024Open Access

Association of Electrocardiogram Findings With Clinical Outcomes in Patients With Chronic Coronary Syndrome: An Analysis of the ISCHEMIA Trials

Key Result

An abnormal baseline ECG tracing in patients with chronic coronary syndrome was associated with an increased risk of cardiovascular death compared to a normal ECG (aHR 2.01; 95% CI 1.58-2.55).

Study Design

Type

Observational (n=5,876)

Structured PICO

Does an abnormal baseline ECG tracing predict an increased risk of cardiovascular death in patients with chronic coronary syndrome?

Population

5,876 patients with chronic coronary syndrome from the ISCHEMIA and ISCHEMIA-CKD trials

Intervention

Abnormal ECG tracing at baseline (including ST-segment depression ≥ 0.5 mm, T-wave inversion ≥ 1 mm, LBBB, and RBBB)

Comparator

Normal ECG tracing at baseline

Outcome

Cardiovascular deathhard clinical

Baseline ECG abnormalities, including ST-segment depression, T-wave inversion, and bundle branch blocks, are strong independent predictors of cardiovascular death in patients with chronic coronary syndrome.

Main Result

Effect estimate: aHR 2.01 (95% CI 1.58-2.55)

Absolute Event Rate: 8.6% vs 3.3%

Abstract

OBJECTIVE: We aimed to investigate the association of electrocardiogram (ECG) findings with outcomes in patients with chronic coronary syndrome. METHODS: This secondary analysis of the ISCHEMIA and ISCHEMIA-CKD trials divided patients with chronic coronary syndrome into two groups, those with a normal ECG tracing and abnormal ECG tracing. Repolarization abnormalities included ST-segment depression ≥ 0.5 mm and T-wave inversion ≥ 1 mm; conduction abnormalities included left and right bundle branch block (LBBB and RBBB). The primary endpoint was cardiovascular death. Outcomes were assessed using a covariate-adjusted Cox-regression model. RESULTS: Of 5876 patients, 2901 (49.4%) had a normal and 2975 (50.6%) an abnormal ECG tracing. An abnormal ECG tracing at baseline, compared with a normal ECG tracing, was associated with an increased risk of cardiovascular death (257 of 2975 8.6% vs. 97 of 2901 3.3%, adjusted hazard ratio aHR 2.01, 95% CI 1.58-2.55) over a median follow-up period of 3.1 years (IQR 2.1-4.2). This finding was consistent across subgroups except for patients with black skin color and current smokers, in whom an abnormal ECG was not significantly associated with increased risk of cardiovascular death. Individual ECG abnormalities (ST-segment depression aHR 2.0, 95% CI 1.52-2.63, T-wave inversion aHR 1.89, 95% CI 1.40-2.54, LBBB aHR 1.74, 95% CI 1.05-2.90, and RBBB aHR 1.52, 95% CI 1.04-2.22) were independently associated with an increased risk of cardiovascular death. CONCLUSION: In patients with chronic coronary syndrome, an abnormal ECG tracing was associated with an increased risk of cardiovascular death. Our findings underscore the importance of the ECG in cardiovascular risk stratification and prognostication. TRIAL REGISTRATION: NCT01471522, BioLINCC ID 14539.