Operation for unstable angina pectoris: factors influencing adverse in-hospital outcome

Use of del Nido cardioplegia in acute coronary syndrome cases with decreased ejection fraction

BACKGROUND

There has been increasing interest in using del Nido cardioplegia in adult cardiac surgery. However, there is limited evidence for its efficacy in patients with acute coronary syndrome and reduced ejection fraction.

METHODS

This study examined patients with decreased ejection fraction (EF < 40%) who were hospitalized due to acute coronary syndrome and received either del Nido (DN) or cold blood cardioplegia (CB). The patients were matched based on age, gender, myocardial infarction at baseline, and number of conducted surgical procedures. An analysis was conducted on postoperative biomarker release (high-sensitivity troponin T and isoenzyme creatine kinase-MB (CK-MB)), changes in myocardial contractility and perioperative outcomes.

RESULTS

62 pairs of patients with similar baseline characteristics were selected. 51.6% of pairs underwent isolated coronary artery bypass grafting, while 48.4% underwent a complex procedure. Postoperative troponin values did not differ significantly at 12 h (median (IQR): 606.7 (381.4-974.8) pg/mL vs. 552 (231.8-1579.5) pg/mL; p = 0.913), nor did CK-MB (median (IQR): 24.3 (12.6-45.5) ng/mL vs. 23.7 (12.3-49.8) ng/mL; p = 0.972). The postoperative EF was similar between groups (median (IQR): 30% (30-35%) vs. 34% (30-38%); p = 0.323). No difference in perioperative mortality, myocardial infarction, stroke, or composite endpoint was noted. In a multivariate analysis, the cardioplegia protocol did not affect biomarker release or changes in ejection fraction. The first stage of acute kidney injury was more frequent in the CB group (28.5% vs. 9.7%, p = 0.033).

CONCLUSIONS

Both del Nido and cold blood cardioplegia provide adequate cardioprotection in patients with acute coronary syndrome with decreased ejection fraction.

Outcome of acute myocardial infarction versus stable coronary artery disease patients treated with coronary bypass surgery

OBJECTIVE

To study the long-term outcome differences between acute myocardial infarction (MI) and stable coronary artery disease (CAD) patients treated with coronary artery bypass grafting (CABG).

METHODS

We studied retrospectively patients with MI (n = 1882) or stable CAD (n = 13117) treated with isolated CABG between 2004 and 2014. Inverse propensity probability weight adjustment for baseline features was used. Median follow-up was 7.9 years.

RESULTS

In-hospital mortality (8.6% vs. 1.6%; OR 5.94; p < .0001) and re-sternotomy (5.5% vs. 2.7%; OR 2.07; p < .0001) were more common in MI patients compared to stable CAD patients. Hospital surviving MI patients had higher all-cause mortality (28.2% vs. 22.2%; HR 1.37; p = .002) and MACE rate (34.4% vs. 27.4%; HR 1.22; CI 1.00-1.50; p = .049) at 10-year follow-up. Cardiovascular mortality (15.9% vs. 12.7%; HR 1.36; p = .017) and rate of new myocardial infarction (12.0% vs. 9.8%; HR 1.40; p = .034) were also higher in MI patients during follow-up. In follow-up of stabilized first-year survivors, the difference in all-cause (26.5% vs. 20.7%; HR 1.40; p = .003) and cardiovascular (14.2% vs. 11.4%; HR 1.37; p = .027) mortality continued to increase between MI and stable CAD patients.

CONCLUSION

MI patients have poorer short- and long-term outcomes compared to stable CAD patients after CABG and risk difference continues to increase with time. Key Messages Patients with myocardial infarction have poorer short- and long-term outcomes compared to stable coronary artery disease patients after coronary artery bypass grafting (CABG). Higher risk of death continues also in stabilized first-year myocardial infarct survivors. The importance of efficient secondary prevention and follow-up highlights in post-myocardial infarct population after CABG.

Timing of coronary artery bypass grafting after acute myocardial infarction: does it influence outcomes?

Introduction

The optimal timing of coronary artery bypass grafting (CABG) operations in patients with recent acute myocardial infarction (AMI) remains unclear.

Aim

To assess the influence of timing on post-operative outcomes in patients undergoing CABG following AMI.

Material and methods

In this retrospective analysis 12,224 consecutive patients undergoing CABG were included. 2477 (20.5%) patients had a history of AMI. Based on timing, patients were divided into 3 groups: those operated within 7 days of AMI; those operated after 7 days but within 1 month; and a third group operated after 1 month but within 3 months. The 3 groups were compared in terms of baseline, intra-operative, and post-operative morbidity and mortality. Multivariate analysis was carried out to assess the independent influence of timing of CABG on outcomes.

Results

There was no difference in terms of previous neurological events (p = 0.554), presence of carotid artery disease (p = 0.555), prevalence of hypertension (p = 0.119), diabetes (p = 0.144), hypothyroidism (p = 0.53), chronic obstructive pulmonary disease (p = 0.079), peripheral vascular disease (p = 0.771), and impaired left ventricular function (p = 0.072). On univariate analysis, mortality risk was highest between 1 week and 1 month (p = 0.003). Multivariate analysis showed that the closer the MI and CABG duration, the higher the mortality (co-efficient -0.517; p = 0.019; odds ratio = 0.596; 95% CI: 0.388-0.917).

Conclusions

The duration between MI and CABG has a direct influence on outcomes after CABG. While it is clear that the longer the duration between MI and CABG, the lower the mortality risk, it is however difficult to decide on an exact cut-off time frame.

Off-Pump Surgery: A Choice in Unstable Angina

The benefit and safety of off-pump coronary artery bypass surgery in patients with unstable angina was assessed retrospectively. From February 1996 to October 2001, 5,306 patients underwent multivessel off-pump coronary artery bypass, of whom 920 (17%) had unstable angina. In these 920 patients, ejection fractions ranged from 15% to 70%, 203 (22%) had an ejection fraction of 20%–35%, and 11 (1%) had an ejection fraction < 20%. Triple-vessel disease was present in 625 patients. Preoperative intraaortic balloon pump support was used in 28 patients. Operative approaches included mid sternotomy (86%), lower partial sternotomy (9%), and left anterior thoracotomy (2%). The number of grafts ranged from 1 to 5 with a mean of 2.43 ± 0.86, and 92.3% of patients received a left internal mammary artery graft. Twenty-two patients need intraoperative intraaortic balloon pumping. Ten patients (1%) suffered perioperative myocardial infarction. The mean hospital stay was 7.8 ± 4.3 days. Hospital mortality was 2/920 (0.22%). Intraaortic balloon pumping was helpful in these cases of unstable angina refractory to medical therapy. Off-pump coronary artery surgery was found to be safe and beneficial in these patients.

Acute Coronary Syndrome Does Not Have a Negative Impact on Outcomes after Coronary Artery Bypass Grafting in Patients with Left Main Disease

PURPOSE

Early and long-term outcomes of coronary artery bypass grafting (CABG) in patients with left main disease (LMD) with acute coronary syndrome (ACS) have never been assessed.

METHODS

Between September 2004 and April 2012, 459 patients with LMD underwent first-time isolated CABG. Of those, 191 patients had ACS and 268 did not. Early and late postoperative outcomes were compared between two groups.

RESULTS

Patients in the LMD+ACS group were older and more likely to be female. Left ventricular ejection fraction was lower in the LMD+ACS group. In both groups, bilateral internal thoracic artery grafts were used in over 90% of patients and off-pump technique in over 95%. Operative death rate was not significantly different between the groups (LMD+ACS: 2.1% vs.

LMD-ACS

0.4%). Log-rank test revealed that the actuarial survival rate (79.2 ± 3.7% vs. 81.5 ± 3.5%) and freedom from major adverse cardiac and cerebrovascular events (MACCE) (69.2 ± 4.2% vs. 67.0 ± 4.1%) were similar between groups at 7 years. Multivariate analyses demonstrated that ACS was not identified as an independent predictor of operative death, late mortality, and late MACCE.

CONCLUSION

ACS did not have a negative impact on early and late outcomes of CABG in patients with LMD.

Staged revascularization in critically ill patients with coronary artery disease

BACKGROUND

Critically ill patients undergoing bypass surgery experience a higher mortality and morbidity.

HYPOTHESIS

The study was undertaken to evaluate the efficacy and value of percutaneous transluminal coronary angioplasty (PTCA) as a bridge to coronary artery bypass graft surgery (CABG) in high-risk patients with refractory unstable angina or cardiogenic shock.

METHODS

We present 11 seriously unstable patients with severe multivessel coronary artery disease undergoing culprit vessel PTCA. Angioplasty was performed not as a definitive procedure but rather as a bridge to surgical revascularization. All the patients had sustained at least one myocardial infarction prior to catheterization, all had refractory unstable angina, eight patients had only a single patent coronary artery, and five patients were in cardiogenic shock.

RESULTS

Following PTCA, all patients enjoyed a stable in-hospital period. One patient died 12 weeks after successful PTCA while awaiting second CABG. Seven patients subsequently underwent CABG and are doing well. The remaining three patients were also advised to undergo CABG, but elected to continue medical management.

CONCLUSIONS

Coronary angioplasty of the culprit vessel may play a role as a bridge to surgery in critically ill patients.

Impact of Unstable Angina on Outcomes of Transmyocardial Laser Revascularization Combined With Coronary Artery Bypass Grafting

BACKGROUND

For sole therapy transmyocardial laser revascularization (TMR), unstable angina has been demonstrated to be a significant independent predictor of operative mortality. The objective of this study was to investigate the preoperative risk profile of patients undergoing TMR plus coronary artery bypass graft surgery (CABG) and to determine the impact of unstable angina on outcomes.

METHODS

Using The Society of Thoracic Surgeons National Cardiac Database from 1998 to 2003, 5,618 patients underwent TMR plus CABG. These patients were compared with 932,715 patients who underwent CABG only operations.

RESULTS

The TMR plus CABG patients had a significantly higher incidence of diabetes (50% versus 34%), renal failure (7% versus 5%), peripheral vascular disease (20% versus 16%), reoperative surgery (26% versus 9%), three-vessel coronary artery disease (80% versus 71%), hyperlipidemia (73% versus 62%; p < 0.001 for all comparisons). The incidence of preoperative unstable angina was similar (46% versus 47%). The unadjusted perioperative mortality was 3.8% for TMR plus CABG patients. When unstable angina patients were removed, the observed mortality for TMR plus CABG was decreased to 2.7%.

CONCLUSIONS

It is likely that patients who undergo TMR plus CABG have a higher prevalence of diffuse coronary disease based on their preoperative demographics. Despite the increased risk associated with such anatomy, the mortality rate was not significantly increased when TMR was added to CABG in an effort to provide a more complete revascularization. As was noted from the outcomes of sole therapy TMR, in unstable angina patients, TMR plus CABG carries a higher risk, but this risk is not significantly different from that of such patients treated with CABG alone.

Continuous cold blood cardioplegia improves myocardial protection: a prospective randomized study

BACKGROUND

To assess the influence on myocardial protection of the rate of infusion (continuous vs intermittent) of cold blood cardioplegia administered retrogradely during prolonged aortic cross-clamping. The end-points were ventricular performance and biochemical markers of ischemia.

METHODS

Seventy patients undergoing myocardial revascularization for three-vessel disease were prospectively randomized to receive intermittent or continuous retrograde cold blood cardioplegia. Hemodynamic measurements were obtained using a rapid-response thermodilution catheter and included right ventricular ejection fraction, cardiac output, left and right ventricular stroke work index, and systemic and pulmonary vascular resistance. Blood samples were obtained from the coronary sinus before cross-clamp application and immediately after cross-clamp removal for determinations of lactate and hypoxanthine.

RESULTS

The left ventricular stroke work index trend was significantly superior (p = 0.038) by repeated-measures analysis in continuous cardioplegia. Other hemodynamic measurements revealed a similar trend. The need for postoperative inotropic drugs support was reduced in continuous cardioplegia. The release of lactate in the coronary sinus after unclamping was 2.30 +/- 0.12 mmol/L after intermittent cardioplegia and 1.97 +/- 0.09 mmol/L after continuous cardioplegia (p = 0.036). The release of hypoxanthine was 20.47 +/- 2.74 micromol/L in intermittent cardioplegia and 11.77 +/- 0.69 micromol/L in continuous cardioplegia (p = 0.002).

CONCLUSIONS

Continuous cold blood cardioplegia results in improved ventricular performance and reduced myocardial ischemia in comparison with intermittent administration.

The intraaortic balloon pump in cardiac surgery

The intraaortic balloon pump (IABP) has been used in cardiac operations since the late 1960s. Over the years, with refinements in technology, its use has expanded; the IABP is now the most commonly used mechanical assist device in cardiac operative procedures. This review provides an evaluation of evidence for the efficacy of IABP use in different clinical scenarios, using the American College of Cardiology/American Heart Association classification of evidence where appropriate. We evaluated complications and outcomes associated with IABP use, and attempted to draw conclusions regarding the use of the IABP in different clinical situations. We examined the trends and variation in utilization over time and across centers. We discussed the IABP in light of new cardiac assist devices and the changing patient population and management strategies. Lastly, we identified areas of future research.

Trends in intraaortic balloon counterpulsation complications and outcomes in cardiac surgery

BACKGROUND

As the proportion of high-risk patients for cardiac surgery increases, use of intraaortic balloon counterpulsation (IABC) has increased, especially in preoperative therapy. Although the efficacy and cost-effectiveness of IABC have been demonstrated, historically higher complication rates have dissuaded some practitioners from using IABC.

METHODS

This report describes IABC use in cardiac surgery, examines trends in complications over time, and compares outcomes in preoperative versus postoperative use in a single prospective worldwide registry over the past 3 years.

RESULTS

The frequency of IABC use appears to be increasing with time as the complication rates have dramatically fallen. The overall IABC-related complication rate was 6.5% (460/7,101), and the rate of major complications (requiring surgery or transfusion) was 2.1% (148/7,101). Hospital mortality was significantly lower in patients treated preoperatively with IABC compared with patients treated postoperatively (8.8% vs 28.2%, p < 0.0001), although this may be due to a selection bias in the postoperative group.

CONCLUSIONS

Preoperative IABC therapy leads to better patient outcomes in high-risk CABG patients. Improved IABC technology and better surveillance have led to increased use with lower complication rates. Although selection bias is inherent in retrospective studies, the Benchmark Counterpulsation Outcomes Registry outcomes are in close concordance to prospective randomized studies previously reported.

Evaluation of coronary artery bypass grafting in acute myocardial infarction

OBJECTIVES

We evaluated coronary artery bypass grafting (CABG) in acute myocardial infarction (AMI) within 14 days of onset.

METHODS

Of 1,450 patients undergoing isolated CABG in the last 12 years we retrospectively analyzed operative risk factors and studied the use of CABG in treating AMI in 66 undergoing surgery during the AMI phase. We divided them into 2 groups: Group D (deceased: n = 8) and Group S (survivors: n = 58).

RESULTS

Total operative mortality was 12.1% (8/66). Univariate analysis showed the following preoperative parameters to be significant in Group D: diabetes mellitus, cardiogenic shock, shortness of the interval between AMI onset and surgery, mean peak creatine phosphokinase-MB, AMI of the left main trunk, and failed recanalization of the infarcted artery. Multivariate analysis showed diabetes mellitus, cardiogenic shock, and AMI of the left main trunk as independent risk factors for hospital mortality. Intra-operative parameters between groups showed no statistical difference. Mortality in patients who did not suffer cardiogenic shock was zero.

CONCLUSION

Maintenance of hemodynamics in the early phase is vital in treating AMI. The most important element in surgical intervention is revascularization of main branches. We concluded that CABG in AMI involves relatively low risk.

Off-pump coronary bypass surgery causes less immediate postoperative coronary endothelial dysfunction compared to on-pump coronary bypass surgery

OBJECTIVE

In this study a comparison of the vascular reactivity in the coronary circulation was investigated by injection of acetylcholine (ACh) and adenosine (ADO) in coronary bypass patients, operated on with or without the assistance of heart-lung machine. The patients operated on with heart-lung machine were further divided into subjects with stable or unstable angina pectoris.

METHODS

Nine patients with stable angina pectoris subjected to off-pump surgery (target arterial occlusion time of 11+/-0.5 min) and 18 patients subjected to on-pump surgery (nine patients with stable angina and nine patients with unstable angina; cross-clamp time of 43+/-3 and 32+/-2 min, respectively), received ACh (10 microg) and ADO (18 microg) given as bolus injections into a vein-graft anastomosed to a coronary vessel. The blood flow in the vein-graft (i.e. indirectly the flow in the targeted coronary circulation) and hemodynamics were observed.

RESULTS

In the off-pump group, ACh evoked an increase with +14+/-12% of control in coronary blood flow, while in the stable on-pump group ACh decreased the blood flow with -60+/-7% of baseline and in the unstable on-pump group the flow was decreased with -38+/-8% of baseline (P<0.001 between the stable on- and off-pump groups, no significant difference between the stable and unstable on-pump groups). ADO significantly increased the coronary blood flow in all three groups; with +81+/-14% in the off-pump patients; with +95+/-14% in the stable on-pump group and with +74+/-13% in the unstable on-pump group (P<0.01 compared to baseline for all three groups). Neither ACh nor ADO injection caused any changes in hemodynamics.

CONCLUSIONS

The present study demonstrates that on-pump coronary bypass surgery appears to be more harmful to the coronary endothelium, in terms of ACh-induced vasoconstriction, compared to off-bypass pump surgery. Furthermore, there is no significant difference in direct smooth muscle vascular reactivity between off-pump and on-pump coronary bypass surgery. No apparent dissimilarities in endothelial dysfunction were observed in the stable and unstable on-pump groups suggesting other causes for differences in post-operative outcome for these patients.

North American experience with the Perma-Flow prosthetic coronary graft

BACKGROUND

The Perma-Flow prosthetic coronary graft is a 5-mm polytetrafluoroethylene tube into which is incorporated a Venturi flow restrictor. An aorto-superior vena caval fistula is created and coronary anastomoses are constructed proximal to the resistor in side-to-side fashion, where arterial pressure is maintained. From November 1992 through December 1995, eight investigational centers in North America have implanted this graft in 40 patients with inadequate autologous alternatives.

METHODS

Patients were selected for inclusion in this study if coronary artery bypass grafting was required and adequate autologous conduit to complete revascularization was not available. Operative data were completed by the implantating surgeon and referred to a central center, the Minneapolis Heart Institute, for correlation. Follow-up was conducted by data coordinators at each institution, and follow-up data were obtained directly from these coordinators for inclusion in the study.

RESULTS

Patient age ranged from 53 to 82 years, and 15 patients were undergoing reoperations (38%). On each Perma-Flow graft one to four coronary side-to-side anastomoses were constructed. In addition, left internal mammary artery (n = 26), greater saphenous vein (8), right internal mammary artery (4), and gastroepiploic artery (4) were used to complete revascularization. Aortic (2) or mitral valve replacement (1) was also carried out. There were seven operative deaths (18%) and two late deaths (4 and 6 months). After 1 to 37 months (mean, 13 +/- 9 months) of follow-up, 29 of 31 surviving patients are asymptomatic. Echocardiographic heart size has not increased from the postoperative value, indicating limited volume load has not affected heart size. Protocol catheterization (n = 32) in 28 patients 1 week to 1 year postoperatively revealed 7 of 73 studied coronary anastomoses (9.5%) and two distal extensions and resistors were occluded (7%). In 1 patient during sternal debridement at 1 year, no flow was found in the graft.

CONCLUSIONS

The Perma-Flow graft is a useful adjunct to complete revascularization in patients with deficient autologous conduit.