Of all patients in Thai PCI registry, 5,479 STEMI patients were eligible and included in this study. The mean age was 62.6 (SD=12.6) years, 73.6% of patients were males.
There were 204, 2154, and 3121 patients in the youngest, middle, and oldest groups, respectively. Characteristics of the patient were compared by age groups, see Table 1. Compare among all groups, the youngest and middle-aged patients were mainly male gender (89.2% vs 82.4% and 66.6%; p < 0.001), were current smoker (70.6%, 57.7%, 34.1%; p < 0.001), had BMI≥25 kg/m2 (60.8%, 44.1%, 26.1%; p < 0.001), and had greater family history of premature CAD (6.9%, 7.2%, 2.9%; p < 0.001). In terms of health coverage scheme, almost two-thirds of each group had universal coverage, but the youngest group had a social security service scheme in the highest number (26%), whereas the oldest group was covered with government service/state enterprise (20.4%) (p< 0.001). The oldest group were more frequently diagnosed with hypertension, dyslipidemia, cerebrovascular disease, chronic lung disease, prior heart failure, prior valve surgery/procedure, chronic kidney disease (CKD), prior coronary bypass graph (CABG), and diabetes mellitus.
After acute MI presentation, the youngest patients significantly presented to the hospital earlier than other groups with significantly lower median time (IQR) of first medical contact (FMC) to device of 3.4 hours (1.9, 7.9), 4.2 hour (2.2, 11.1) and 4.8 hour (2.6, 12.3) (p < 0.001), respectively (see Table 2). They also had greater proportion of primary PCI than older patients (69.0%, 61.1%, 59.8%; p = 0.017) and got Alteplase thrombolytic in higher number (5.3%, 0.4%, 0.4%; p < 0.001). On the other hand, they seemed less likely to receive pharmaco-invasive treatment than other groups (13.8%, 16.3%, 18.8%). Regarding the extent and severity of disease vessel, the oldest group was significantly associated with triple vessel disease (10.3%, 18.8%, 25.5%) and left main disease (4.4%, 5.3%, 9.5%) with p < 0.001, whereas the younger groups highly associated with single vessel disease. Among STEMI patients, the significant stenosis lesions in LAD were found in 83%, 87.9%, 87.9%, and RCA in 81.2%, 83.8%, 86.0% each group, that did not show statistical differences. The median calculated syntax score (IQR) was notably, but not surprisingly, higher in the oldest group (10 (6, 18), 13 (7, 20), 16 (9, 23); p = 0.009). Although the IRA was insignificantly different among groups, when thoroughly explored the stenotic segment involvement, we found that the youngest group had the highest percentage of proximal LAD stenosis (99%, 90%, 80%; p = 0.003) while the oldest group remarkably had the highest percentage of left main segment stenosis.
Concerning PCI procedures, though there was insignificant difference in PCI status and the percentage of PCI for culprit lesions, the oldest patients seemed to have less emergency PCI than the younger ones (81.9%, 73.6%, 74.1%), see Table 2. Moreover, elderly patients significantly associated with cardiogenic shock at start of PCI (14.7%, 17.0%, 24.7%, p<0.001) and use of IABP (6.9%, 5.7%, 9.7%, p < 0.001). On the contrary, the youngest group had thrombus burden (p<0.001) and aspiration catheters were most use (p = 0.002).
Regarding intra and post procedural clinical events, unsurprisingly, the oldest group had significantly higher events of cardiogenic shock, heart failure, RBC/whole blood transfusion, bleeding within 72 hours, arrhythmia requiring treatment, ET-tube intubation, and temporary pacemaker insertion, death in hospital and death in one year than both younger groups, see Table 3. Interestingly, there were trends of higher events of new requirement for dialysis, cardioversion/defibrillation, procedural failure, procedural complications, and prolonged median hospital stay in both youngest and oldest groups compared to the middle-aged group. Adding to this, the youngest patients had more frequently been prescribed with GP IIb/IIIa inhibitor (23.2%, 16.5%, 15.2%; p = 0.009).
Procedural complications and cause of procedural failure were described, see Supplement Table 1. No reflow after primary PCI was more frequently observed in both youngest and oldest groups comparing to the middle-aged group (2.9%, 1.5%, 3.3%; p <0.001).
Of all 5,479 patients, 7 (3.4%) out of 237 patients in the youngest group died during hospital stay compared to 72 (3.3%) out of 2,512 middle-aged patients and 287 (9.2%) out of 3,624 older patients (p < 0.001), see Table 3. The death at 1 year among all patients as well was notably higher in the oldest group (22.3%) compared with the other younger groups (8.8% in patients age ≤ 40 and 7.9% in patients aged 41-60, respectively).
Univariate and multivariate analyses were performed to identify risk factors associated with death within a year for each age group, see Table 4 and Supplement Table 2. Among patients aged ≤ 40 years, factors associated with increased mortality included chronic lung disease, prior heart failure, left main disease, and having procedural failure with HR of 84.67 (14.38, 498.61), 10.27 (2.71, 38.94), 9.09 (2.28, 36.22), and 12.07 (2.83, 51.53), respectively. For age 41-60 years, left main disease and procedural failure remained significantly with additional CKD and diabetes with HR of 2.60 (1.57, 4.29), 2.42 (1.30, 4.50), 3.84 (2.77, 5.31) and 1.46 (1.06, 2.01), respectively, see Table 4.
For age > 60 years, chronic lung disease, CKD, heart failure, left main disease, and procedural failure were still significantly associated with death with additional risk factors of cerebrovascular disease, dialysis, peripheral arterial disease, prior valve surgery, and procedure complications with HR of 1.46 to 2.51; whereas male and high BMI significantly lowering risk of death by approximately 30%; see Table 4.