Association Between Flow Impairment in Dominant Coronary Atrial Branches and Atrial Arrhythmias in Patients With ST-Segment Elevation Myocardial Infarction

Coronary Angiography-Derived Index of Microcirculatory Resistance Associated With New-Onset Atrial Fibrillation in Patients With STEMI

BACKGROUND

Coronary angiography-derived index of microcirculatory resistance (caIMR) can effectively assess coronary microvascular dysfunction in patients with ST-segment elevation myocardial infarction (STEMI). This study aimed to explore the role of caIMR in the occurrence of new-onset atrial fibrillation (NOAF) in patients with STEMI.

METHODS

This was a single-centre retrospective clinical observational study. Patients diagnosed with STEMI from September 2019 to December 2022 were included. caIMR was calculated using computational flow and pressure simulations. During admission, suspicious heart rhythm was recorded by electrocardiographic (ECG) monitoring, and NOAF was confirmed by an immediate 12-lead ECG.

RESULTS

A total of 739 patients were enrolled, including 57 (7.7) with NOAF. caIMR was significantly correlated with microvascular obstruction (R = 0.604; P < 0.001) and infarct size (R = 0.514; P < 0.001). After adjusting for potential confounding factors, the results showed that caIMR (odds ratio 1.058, 95% confidence interval 1.035-1.083; P < 0.001) was an independent risk factor for NOAF in patients with STEMI. Receiver operating characteristic analysis showed that the area under the curve of caIMR for predicting NOAF was 0.716. Compared with the caIMR < 27.35 U group, the caIMR ≥ 27.35 U group had higher high-sensitivity troponin T and N-terminal pro-B-type natriuretic peptide levels. When caIMR was added to the model, the reclassification and discriminant abilities improved significantly.

CONCLUSIONS

Higher caIMR was an independent risk factor for NOAF in patients with STEMI. The caIMR had high specificity and sensitivity for predicting NOAF in patients with STEMI. The integration of caIMR into clinical risk factors showed significantly increased predictability for NOAF in patients with STEMI.

Effects of Atrial Ischemia on Left Atrial Remodeling in Patients with ST-Segment Elevation Myocardial Infarction

BACKGROUND

Adverse left atrial (LA) remodeling after ST-segment elevation myocardial infarction (STEMI) has been associated with poor prognosis. Flow impairment in the dominant coronary atrial branch (CAB) may affect large areas of LA myocardium, potentially leading to adverse LA remodeling during follow-up. The aim of this study was to assess echocardiographic LA remodeling in patients with STEMI with impaired coronary flow in the dominant CAB.

METHODS

Of 897 patients with STEMI, 69 patients (mean age, 62 ± 11 years; 83% men) with impaired coronary flow in the dominant CAB (defined as Thrombolysis In Myocardial Infarction flow grade < 3) were retrospectively compared with an age- and sex-matched control group of 138 patients with normal dominant CAB coronary flow.

RESULTS

Patients with dominant CAB-impaired flow had higher peak troponin T (3.9 μg/L [interquartile range, 2.2-8.2 μg/L] vs 3.2 μg/L [interquartile range, 1.5-5.6 μg/L], P = .009). No differences in left ventricular ejection fraction or mitral regurgitation were observed between groups at baseline or at follow-up. LA remodeling assessment included maximum LA volume, speckle-tracking echocardiography-derived LA strain, and total atrial conduction time assessed on Doppler tissue imaging at baseline, 6 months, and 12 months. Patients with dominant CAB-impaired flow presented larger LA maximal volumes (26.9 ± 10.9 vs 18.1 ± 7.1 mL/m², P < .001) and longer total atrial conduction time (150 ± 23 vs 124 ± 22 msec, P < .001) at 6 months, remaining unchanged at 12 months. However, all LA strain parameters were significantly lower from baseline (reservoir, 20.3 ± 10.1% vs 27.1 ± 14.5% [P < .001]; conduit, 9.1 ± 5.6% vs 12.8 ± 8% [P < .001]; booster, 9.1 ± 5.6% vs 12.8 ± 8% [P < .001]), these differences being sustained at 6- and 12-month follow-up.

CONCLUSIONS

Atrial ischemia resulting from impaired coronary flow in the dominant CAB in patients with STEMI is associated with LA adverse anatomic and functional remodeling. Reduced LA strain preceded LA anatomic remodeling in early phases after STEMI.