[Incidence and outcomes of perioperative myocardial infarction associated with coronary artery bypass surgery].

INTRODUCTION: Perioperative myocardial infarction (PMI) after CABG can contribute to in-hospital morbidity and mortality, however, its clinical significance on long-term outcome, remains inadequately addressed. We studied both 30-day mortality and long-term effects of PMI in Icelandic CABG-patients. MATERIALS AND METHODS: A retrospective nationwide-study on 1446 consecutive CABG-patients operated at Landspitali in Iceland 2002-2018 without evidence of preoperative myocardial infarction. PMI was defined as a tenfold elevetion in serum-CK-MB associated with new ECG changes or diagnostic imaging consistent with ischemia. Patients with PMI were compared to a reference group with uni- and multivariate analyses. Long-term and MACCE-free survival were estimated with the Kaplan-Meier method and logistic regression used to determine factors associated with PMI. The mean follow-up time was 8.3 years. RESULTS: Out of 1446 patients 78 (5.4%) were diagnosed with PMI (range: 0-15.5%) with a significant annual decline in the incidence of PMI (12.7%, p<0.001). Over the same period preoperative aspirin use increased by 22.3% (p<0.018). PMI patients had a higher rate of short-term complications and a 11.5% 30-day mortality rate compared to 0.4% for non-PMI patients. PMI was found to be a predictor of 30-day mortality (OR 15.44, 95% CI: 6.89-34.67). PMI patients had worse 5-year MACCE-free survival (69.2% vs. 84.7, p=0,01), although overall survival was comparable between the groups. CONCLUSIONS: Although PMI after CABG is associated with significantly higher rates of short-term complications and 30-day mortality, long-term survival was similar to the reference group. Therefore, the mortality risk attributable to PMI appears to diminish after the immediate postoperative period.

[New-onset postoperative atrial fibrillation following coronary artery bypass grafting: Incidence, clinical course and short-term outcomes].

INTRODUCTION: The aims of this retrospective study were to investigate the incidence, clinical course and short term outcomes of new-onset postoperative atrial fibrillation (POAF) following coronary artery bypass surgery (CABG). MATERIALS AND METHODS: A nation-wide study on 1622 patients who underwent CABG from 2006-2020 at Landspitali University Hospital. Clinical data were extracted from registries and 121 patients with pre-existing AF excluded, leaving 1501 patients for further analysis. Patient charts and postoperative ECGs were manually reviewed for determining details of POAF, which was defined as a postoperative episode of AF before discharge lasting at least 5 minutes. Patients with POAF (n=483) were compared to non-POAF patients (n=1018). RESULTS: Altogether 483 (32.2%) patients developed POAF; the annual incidence decreasing over time (tau= -0,45, p=0.023). Most patients were diagnosed on the second day postoperatively (43.5%) and over 90% were diagnosed within 4 days. The median number of POAF episodes was 3 (IQR: 1-5), the first episode lasting 1-6 hours in half of the cases and the total POAF-duration being 12 hours median (IQR: 5-30). Over 94% of cases converted to sinus rythm before discharge, with 25 (5.3%) patients being discharged in AF. Most patients were treated with beta-blockers (98.8%), amiodarone (95%) and 14.9% with electric cardioversion. POAF-patients were older, had higher EuroSCORE II and a longer hospital stay, however, they had similar rates of early postoperative stroke and 30 day mortality. CONCLUSION: The incidence of POAF remains high and was associated with prolonged hospital stay, but not significantly higher 30 day mortality or early postoperative stroke compared to patients in sinus rhythm. POAF-episodes were predominantly transient and almost 95% of patients were discharged in sinus rythm.

[Impact of renal dysfunction on early outcomes of coronary artery bypass grafting surgery].

INTRODUCTION: Impaired renal function as seen in chronic kidney disease (CKD) is a known risk factor for coronary artery diseases and has been linked to inferior outcome after myocardial revascularization. Studies on the outcome of coronary bypass grafting (CABG) in CKD-patients are scarce. We aimed to study this subgroup of patients following CABG in a well defined whole-nation cohort, focusing on short term complications and 30 day mortality. MATERIALS AND METHODS: A retrospective study on 2300 consecutive patients that underwent CABG at Landspítali University Hospital 2001-2020. Patients were divided into four groups according to preoperative estimated glomerular filtration rate (GFR), and the groups compared. GFR 45-59 mL/mín/1.73m2, GFR 30-44 mL/mín/1.73m2, GFR <30 mL/mín/1.73m2 and controls with normal GFR (≥60 mL/mín/1.73m2). Clinical information was gathered from medical records and logistic regression used to estimate risk factors of 30-day mortality. RESULTS: Altogether 429 (18.7%) patients had impaired kidney function; these patients being more than six years older, having more cardiac symptoms and a higher mean EuroSCORE II (5.0 vs. 1.9, p<0.001) compared to controls. Furthermore, their left ventricular ejection fraction was also lower, their median hospital stay extended by two days and major short-term complications more common, as was 30 day mortality (24.4% vs. 1.4%, p<0.001). In multivariate analysis advanced age, ejection fraction <30% and GFR <30 mL/min/1.73m2 were independent predictors of higher 30-day mortality (OR=10.4; 95% CI: 3.98-25.46). CONCLUSIONS: Patients with impaired renal function are older and more often have severe coronary artery disease. Early complications and 30-day mortality were much higher in these patients compared to controls and advanced renal failure and the strongest predictor of 30-day mortality.

Long-term outcome of surgical revascularization in patients with reduced left ventricular ejection fraction-a population-based cohort study.

OBJECTIVES: Surgical revascularization is an established indication for patients with advanced coronary artery disease and reduced left ventricular ejection fraction (LVEF). Long-term outcomes for these patients are not well-defined. We studied the long-term outcomes of patients with ischaemic cardiomyopathy who underwent surgical revascularization in a well-defined nationwide cohort. MATERIALS AND METHODS: A retrospective study on 2005 patients that underwent isolated coronary artery bypass grafting in Iceland between 2000 and 2016. Patients were categorized into two groups based on their preoperative LVEF; LVEF ≤35% (n = 146, median LVEF 30%) and LVEF >35% (n = 1859, median LVEF 60%). Demographics and major adverse cardiac and cerebrovascular events were compared between groups along with cardiac-specific and overall survival. The median follow-up was 7.6 years. RESULTS: Demographics were similar in both groups regarding age, gender and most cardiovascular risk factors. However, patients with LVEF ≤35% more often had diabetes, renal insufficiency, chronic obstructive pulmonary disease and a previous history of myocardial infarction. Thirty-day mortality was 4 times higher (8% vs 2%, P < 0.001) in the LVEF ≤35%-group compared to controls. Overall survival was significantly lower in the LVEF ≤35%-group compared to controls, at 1 year (87% vs. 98%, P < 0.001) and 5 years (69% vs. 91%, P < 0.001). In multivariable analysis LVEF ≤35% was linked to inferior survival with an adjusted hazard ratio of 2.0 (95%-CI 1.5 - 2.6, p<0.001). CONCLUSIONS: A good long-term outcome after coronary artery bypass grafting can be expected for patients with reduced LVEF, however, their survival is still significantly inferior to patients with normal ventricular function.

[Incidence and predictors of prolonged intensive care unit stay after coronary artery bypass in Iceland].

INTRODUCTION: To maximize the use of intensive care unit (ICU) re--sources, it is important to estimate the prevalence and risk factors for prolonged ICU unit stay after coronary artery bypass grafting (CABG) surgery. MATERIAL AND METHODS: This retrospective cohort study included all patients who underwent primary isolated CABG at Landspitali between 2001 and 2018. Patient information was collected from hospital charts and death registries. Patients who stayed in the ICU for the conventional one night postoperatively were compared with those who needed longer stays in the ICU. Survival rate was estimated with the Kaplan-Meier method. Predictors for prolonged ICU stay were calculated with logistic regression and the outcome used to create a calculator that estimates the probability of prolonged ICU stay. RESULTS: Out of 2177 patients, 20% required prolonged ICU stay. Patients with prolonged stay were more frequently female (23% vs 16%, p=0.001), had a higher rate of cardiovascular risk factors and higher EuroSCORE II (4.7 vs. 1.9, p<0.001). They also had a higher rate of impaired renal function before surgery (14% vs. 4%, p<0.001) and emergent surgery (18% vs. 2%, p<0.001). Furthermore, these patients had higher rates of both short-term and long-term complications, and lower long-term survival (85% vs 68% five-year survival rate, p<0.0001). Independent risk factors for prolonged ICU stay were advanced age, female gender, EuroSCORE II, history of heart diseases, impaired renal function and emergent surgery.  Conclusions: Every fifth patient had a prolonged ICU stay after CABG. Several risk factors predicted prolonged ICU stay after CABG, in particular patients' medical condition before surgery, EuroSCORE II and emergent surgery. A better understanding of the risk factors for prolonged ICU stay will hopefully aid in scheduling CABG surgeries at Landspitali.

[The use of Intra Aortic Balloon Pump in Coronary Artery Bypass Graft Surgery].

INTRODUCTION: Intra-aortic balloon pump (IABP) is a mechanical device that increases cardiac output by increasing diastolic blood flow to the coronary arteries and lowers the afterload of the left ventricle in systole. IABP is primarily used in acute heart failure, that includes patients that have to undergo coronary artery bypass grafting (CABG). Its usage, however, in cardiac surgery has been declining with ongoing controversy regarding its benefits. The aim of this study was to assess the use and indications and outcome of IABP related to CABG surgery. MATERIAL AND METHODS: The study was retrospective and included 2177 patients that underwent CABG at Landspítali during 2001-2018. We compared those who received an IABP with controls, using uni- and multivariate analysis. Long term survival and complications (major adverse cardiovascular and cerebral events, MACCE) was estimated with Kaplan-Meier method. RESULTS: A total of 99 (4.5%) patients received an IABP. The incidence was highest in 2006 (8.9%) and lowest in 2001 (1.7%), but the incidence did not change during the study period (p=0.90). Most patients received the pump before (58.6%) or during (34.3%) CABG, but only 6.1% after surgery. Complication rate was 14.1%, with bleeding from the insertion site in the groin being the most common complication. Thirty day mortality was higher in the IABP group compared with controls (22.2% vs 1.3%, p<0.001) and both 5-year survival (56.4% vs 91.5%, 95% CI: 0.47-0.67) and 5-year MACCE-free survival (46.9% vs 83.0%, 95% CI: 0.38-0.58) were inferior. CONCLUSIONS: Less than 5% of patients received IABP in relation to CABG in Iceland and the rate hasn't changed much for the last 18 years. Both the complication rate and 30-day mortality was higher in patients in IABP group and both the long term and MACCE-free survival was much worse, probably mostly related to worse overall clinical condition of the patient that received IABP.