Atrioventricular Coupling Index: A Novel Approach to Risk-Stratification for Major Adverse Cardiovascular Events in Patients With ST-Elevation Myocardial Infarction.

Background: Left atrioventricular coupling index (LACI) has prognostic value in acute myocardial infarction (AMI) patients, while the role of right atrioventricular coupling index (RACI) remains unclear.

Purpose: To explore the prognostic value of LACI and RACI in AMI patients.

Study Type: Retrospective.

Subjects: 1083 ST-elevation AMI patients (median (interquartile range (IQR)) age, 59 (50-67) years; 916 men; 196 right ventricular myocardial infarction (RVMI) patients) from 2 centers, with MRI within 7 days of percutaneous coronary intervention performed within 12 h of symptoms.

Field Strength/sequence: 3-T, balanced steady state free precession cine sequence.

Assessment: LACI and RACI were calculated as the percentage ratio of indexed atrial to indexed ventricular end-diastolic volume. Patients were followed up via medical records or telephone consultation. The primary outcome, major adverse cardiac events (MACE), includes all-cause death, reinfarction, and hospitalization for heart failure. Incremental prognostic value of LACI and/or RACI for MACE was assessed beyond traditional factors (age, diabetes mellitus, Killip class, LVEF and LGE, which were assessed by MRI images).

Statistical Tests: The prognostic value of LACI and RACI was evaluated using Cox regression. Harrell's C index was used to determine goodness of fit of models. p < 0.05 indicated statistical significance.

Results: During a median 38-month (IQR: 21-55 months) follow-up, 161 of 1083 AMI patients experienced MACE, and 29 of 196 RVMI patients experienced MACE. LACI and RACI were independently associated with MACE and provided significantly improved prognostic value in MACE beyond traditional risk factors in AMI patients (Harrell's C index increased from 0.679 to 0.756 with LACI, to 0.730 with RACI, and to 0.762 with LACI and RACI). Notably, RACI outperformed LACI in RVMI patients (Harrell's C index: 0.84 vs. 0.76).

Data Conclusion: LACI and RACI were associated with MACE independently and provided incremental prognostic value beyond established risk factors.

Evidence Level: 2.

Technical Efficacy: Stage 5.