3.1 Study population

A total of 1358 patients underwent coronary angiography at the University Hospital Basel from May 2015 to September 2023 due to suspected STEMI. After excluding patients with ST-segment elevation but a final diagnosis of myopericarditis (n = 9), coronary sclerosis without stenosis (n = 8), coronary spasm (n = 8), subacute aortic dissection or aneurysm (n = 2), coronary artery dissection (n = 2), or Takotsubo cardiomyopathy (n = 28), 1301 patients were eligible for analysis. A patient flow chart is provided in Supplemental Figure S1.

3.2 New-onset atrial fibrillation (NOAF)

AF was recorded in 17% of all patients (n = 222). Among these, 58% (n = 128) had NOAF and 31% (n = 68) had pre-existing AF prior to the STEMI admission. Of the 128 patients with NOAF, 38% (n = 48) were established with AF in the cardiac catheter laboratory, 31% (n = 39) during days 1–3, and in 32% > day 3 (n = 41). One hundred fifteen (91%) patients suffered from paroxysmal AF and 12 (9.4%) patients from persistent AF (Fig. 1).

Fig. 1

Onset of new-onset atrial fibrillation: The timepoint of new-onset atrial fibrillation is visualized as a bar plot. In the right upper corner, the type of new-onset atrial fibrillation is shown. NOAF new-onset atrial fibrillation

3.3 Baseline characteristics

Baseline characteristics are shown in Table 1. The mean age was 63 ± 12, 21% were female, median pain duration was 3 h, and 5.9% were in cardiogenic shock. When comparing patients with NOAF vs. patients with no AF, patients were significantly older with a mean age of 69 ± 11 vs. 63 ± 12, p < 0.001, were more often in cardiogenic shock with 11% vs. 5.2%, p = 0.038, and showed significantly higher GRACE scores with 178 [160–207] vs. 156 [137–177], p < 0.001, respectively. Baseline characteristics stratified for patients with NOAF and with prior AF are summarized in Supplemental Table S1, where NOAF vs. prior AF patients differed only in age (69 [± 11] vs. 74 [± 9] years, p = 0.013).

Table 1 Baseline characteristics3.4 Transthoracic echocardiography findings

Echocardiographic measurements are summarized in Table 2. Patients with NOAF demonstrated lower left ventricular ejection fraction (LVEF) compared to patients with no AF, 45% vs. 50%, p < 0.001, respectively. The left and right atrial diameters were significantly increased in patients with NOAF compared to patients with no AF: left atrial volume index (LAVI) 35 [28–41] ml/m2 vs. 27 [22–34] ml/m2, p < 0.001, and right atrial area (RA) 17 [14–20] cm2 vs. 15 [13–17] cm2, p = 0.016, respectively.

Table 2 Echocardiographic parameters3.5 Coronary angiogram findings

Coronary angiogram findings are summarized in Table 3. The culprit vessel was the right coronary artery (RCA) in 42 patients (33%), the left circumflex artery (LCX) in 17 patients (13%), and the left anterior descending artery (LAD) in 27 patients (21%) in patients with NOAF. There was no difference to patients with no AF. Patients with NOAF significantly less often suffered single-vessel disease compared to patients with no AF with 29% vs. 40%, p = 0.026, and significantly more often suffered triple-vessel disease with 37% vs. 29%, p = 0.044. The left anterior descending artery (LAD) was most frequently affected in patients with NOAF with stroke (n = 7, 54%) and the right coronary artery (RCA) in patients with major bleeding (n = 5, 56%).

Table 3 Affected vessel in coronary angiography3.6 Anticoagulation

The choice of anticoagulation therapy after the index procedure is summarized in Table 4. Among patients with NOAF, 60 patients (47%) received triple therapy for 1 week thereafter switching to dual therapy, 55 patients (43%) dual antiplatelet therapy, 9 patients (7%) oral anticoagulation (OAC) and single platelet therapy, 2 patients (1.6%) single OAC, and 2 patients (1.6%) single platelet therapy. When comparing NOAF patients with patients with prior AF, patients with NOAF significantly less often received triple therapy (47% vs. 66%, p = 0.010) and significantly more often received dual antiplatelet therapy (43% vs. 15%, p < 0.001) (Supplemental Table S2).

Table 4 Anticoagulation after STEMI3.7 Outcomes

During a median follow-up of 683 days, in patients with NOAF compared to patients with no AF, stroke occurred in 13 patients (10%) vs. 41 patients (3.8%), p = 0.001, major bleeding was found in 9 patients (7%) vs. 18 patients (1.7%), p = 0.001, and death was reported in 21 patients (16%) vs. 73 patients (6.8%), p < 0.001, respectively. When comparing patients with NOAF to patients with prior AF, strokes occurred in 13 patients (10%) vs. 4 (5.9%) (p = 0.31), major bleeding in 9 patients (7%) vs. 5 patients (7.4%) (p > 0.99), and deaths in 21 patients (16%) vs. 15 patients (22%) (p = 0.33).

Kaplan–Meier curves are presented in Fig. 2. When comparing patients with NOAF and patients with no AF, a significant difference was found for in-hospital outcomes, outcomes for 12 months follow-up, and long-term follow-up for all MACE (p < 0.0001) and for each secondary outcome separately: for stroke (p = 0.00085), major bleeding (p < 0.0001), and death (p = 0.00027). Supplemental Tables S3 to S5 contain a detailed overview of clinical characteristics of patients with NOAF suffering from a stroke, major bleeding, or death.

Fig. 2

Kaplan–Meier plots of MACE, death, stroke, and major bleeding: Secondary endpoints during 365 days and in an extended frame during the first 30 days after STEMI for NOAF (blue) and no AF (black). AF atrial fibrillation, MACE major adverse cardiac events, NOAF new-onset atrial fibrillation

Findings were confirmed when only including patients with NOAF occurring during the index-hospitalization (n = 110) (Supplemental Figure S2).

3.8 Risk factors of NOAF

A multivariable regression model using variables from baseline patient characteristics identified by univariable analysis showed that age (OR 1.05, 95% CI 1.02–1.07, p = 0.001), LVEF (OR 0.96, 95% CI 0.95–0.98, p = 0.001), and left atrial diameter (OR 1.08, 95% CI 1.03–1.13, p = 0.002) are independent risk factors for the occurrence of NOAF in STEMI patients (Table 5).

Table 5 Univariable and multivariable logistic regression results for risk factors of NOAF3.9 Risk factors of MACE among all AF patients and NOAF patients

Among patients with NOAF, in the univariable model, age (OR 1.06, 95% CI 1.02–1.11, p = 0.004) and GRACE score (OR 1.02, 95% CI 1.01–1.03, p = 0.010) were risk factors for MACE, while in the multivariable model, only the GRACE score was an independent risk factor with an OR 1.02 (95% CI 1.00–1.03, p = 0.030, Table 6). Univariable and multivariable logistic regression results for risk factors of MACE in all AF patients are presented in Supplemental Table S6.

Table 6 Univariable and multivariable logistic regression results for risk factors of MACE in NOAF (n = 128)