Intracoronary shunts and off-pump surgery

Predictors of perioperative myocardial infarction in patients undergoing off-pump coronary artery bypass grafting

Background

Perioperative myocardial infarction (PMI) increases morbidity and mortality after off-pump coronary artery bypass grafting (CABG). The objective of the current study was to characterize patients with PMI after off-pump CABG and identify its predictors.

Results

We included 1181 patients who had off-pump CABG from 2010 to 2020; 59 patients (5%) had PMI. We compared patients with PMI to those without PMI. Patients with PMI were older (57 (25th–75th percentiles: 51–63) vs. 54 (48–60) years; P = 0.01) and had higher NYHA class (28 (47.46%) vs. 326 (29.06%): P = 0.01). The distal anastomosis time was longer in patients with PMI (28 (23–35) vs. 24 (16–30) min; P ˂ 0.001). Patients with PMI had higher postoperative low cardiac output (10 (18.18%) vs. 1 (0.1%): P ˂ 0.001), prolonged ventilation (12 (8–39) vs. 8 (6–10) h, P ˂ 0.001), ICU (71 (46–138) vs. 24 (23–42) h; P ˂ 0.001), and hospital stay (9 (6–15) vs. 7 (6–8) days; P ˂ 0.001). Mortality was significantly higher in patients with PMI (20 (33.9%) vs. 6 (0.53%); P ˂ 0.001). Older age (OR: 1.05 (95% CI: 1.01–1.1); P = 0.02), increased number of distal anastomoses (OR: 1.74 (95% CI: 1.20–2.50); P = 0.003), preoperative congestive heart failure (OR: 10.27 (95% CI: 2.58–40.95); P = 0.001), and thrombolysis within 24 h of surgery (OR: 15.34 (1.93–121.9); P = 0.01) were associated with increased PMI, while PMI was lower in male patients (OR: 0.42 (95% CI: 0.19–0.93); P = 0.03) and with higher body surface area (BSA) (OR: 0.08 (95% CI: 0.07–0.86); P = 0.04).

Conclusions

Post-off-pump CABG PMI was associated with increased morbidity and mortality. Risk factors for PMI were older age, lower BSA, females, increased distal anastomoses, preoperative heart failure, and thrombolysis.

Protective effect of active perfusion in porcine models of acute myocardial ischemia

Mortality rates associated with off-pump coronary artery bypass (CAB) are relatively high, as the majority of patients requiring CAB are at a high risk for cardiac events. The present study aimed to establish porcine models of acute myocardial ischemia, and evaluate the protective role of shunt and active perfusion. A total of 30 pigs were randomly assigned to five groups, as follows: i) Sham (control); ii) A1 (shunt; stenosis rate, 55%); iii) A2 (shunt; stenosis rate, 75%); iv) B1 (active perfusion; stenosis rate, 55%); and v) B2 (active perfusion; stenosis rate, 75%) groups. Aortic pressure (P₀), left anterior descending coronary pressure (P₁), and coronary effective perfusion pressure (P₁/P₀) were measured. The expression levels of tumor necrosis factor-α (TNF-α), cardiac troponin (cTnI), creatine kinase-myocardial band (CK-MB), interleukin (IL)-6, IL-10, B-cell lymphoma 2 (Bcl-2), and caspase-3 were detected using enzyme-linked immunosorbent assay or western blotting. The myocardial apoptosis rate was determined using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Ischemia models with stenosis rates of 55 and 75% were successfully constructed following suturing of the descending artery. Compared with the control, the 55 and 75% stenosis groups demonstrated significantly decreased P₁/P₀, increased expression levels of TNF-α, cTnI, CK-MB, IL-6, IL-10 and caspase-3, an increased rate of myocardial apoptosis, and a decreased expression level of anti-apoptotic protein, Bcl-2. At 30 min following successful establishment of the model (ST segment elevation to 1 mm), group B demonstrated significantly increased P₁/P₀, decreased expression levels of TNF-α, cTnI, CK-MB, IL-6, IL-10 and caspase-3, a decreased rate of myocardial apoptosis, and an increased expression level of anti-apoptotic protein, Bcl-2. Furthermore, the current study indicated that active perfusion was more efficacious in maintaining myocardial perfusion and alleviating ischemic injury when compared with traditional shunt perfusion.