How to prevent perioperative myocardial injury: the conundrum continues

GNAQ TT(-695/-694)GC Polymorphism Is Associated with Increased Gq Expression, Vascular Reactivity, and Myocardial Injury after Coronary Artery Bypass Surgery

BACKGROUND

Angiotensin II receptor type 1-mediated activation of the α-subunit of the heterotrimeric Gq protein evokes increased vasoconstriction and may promote hypertrophy-induced myocardial damage. The authors recently identified a TT(-695/-694)GC polymorphism in the human Gq promoter, the GC allele being associated with an increased prevalence of cardiac hypertrophy. In this article, the authors tested whether the TT(-695/-694)GC polymorphism is associated with differences in (1) myocardial Gq protein expression, (2) vascular reactivity, and (3) myocardial damage after coronary artery bypass grafting.

METHODS

Gq protein expression was measured in right atrial muscle from 55 patients undergoing coronary artery bypass grafting as were skin perfusion changes (n = 18; laser Doppler imaging), saphenous vein ring vascular reactivity (n = 50, organ bath) in response to angiotensin II, and myocardial damage (227 patients undergoing coronary artery bypass grafting), as assessed by postoperative cardiac troponin I concentration.

RESULTS

Myocardial Gq expression was greater in GC/GC genotypes (GC/GC vs.

TT/TT

1.27-fold change; P = 0.006). Skin perfusion after intradermal angiotensin II injection decreased only in GC/GC genotypes (P = 0.0002). Saphenous vein rings exposed to increasing angiotensin II concentrations showed an almost doubled maximum contraction in GC/GC compared with individuals with the TT/TT genotype (P = 0.022). In patients undergoing coronary artery bypass grafting, baseline cardiac ejection fraction was different (GC/GC: 55 ± 13%; GC/TT: 54 ± 14%; TT/TT: 48 ± 15%; P = 0.037) and postoperative peak cardiac troponin I was greater in patients with the GC/GC (11.5 ± 13.8 ng/ml) than in patients with the GC/TT (9.2 ± 9.2 ng/ml) or patients with the TT/TT genotype (6.6 ± 4.8 ng/ml, P = 0.015).

CONCLUSIONS

The GC/GC genotype of the TT(-695/-694)GC polymorphism is associated with increased Gq protein expression, augmented angiotensin II receptor type 1-related vasoconstriction, and increased myocardial injury after coronary artery bypass grafting, highlighting the impact of Gq genotype variation.

Prediction of perioperative cardiac events through preoperative NT-pro-BNP and cTnI after emergent non-cardiac surgery in elderly patients

Objectives

Clinical risk stratification has an important function in preoperative evaluation of patients at risk for cardiac events prior to non-cardiac surgery. The aim of this study was to determine whether the combined measurement of pre-operative N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and cardiac troponin I (cTnI) could provide useful prognostic information about postoperative major adverse cardiac events (MACE) within 30 days in patients aged over 60 years undergoing emergent non-cardiac surgery.

Methods

The study group comprised 2519 patients aged over 60 years that were undergoing emergent non-cardiac surgery between December 2007 and December 2013. NT-pro-BNP and cTnI were measured during hospital admission. The patients were monitored for MACE (cardiac death, non-fatal myocardial infarction, or cardiac arrest) during the 30-day postoperative follow-up period.

Results

MACE occurred in 251 patients (10.0%). Preoperative NT-pro-BNP and cTNI level were significantly higher in the individuals that experienced MACE than in those who did not (P < 0.001). The confounding factors of age, sex, co-morbidities and preoperative medications were adjusted in a multivariate logistic regression analysis. This analysis showed that preoperative NT-proBNP level > 917 pg/mL (OR 4.81, 95% CI 3.446–6.722, P < 0.001) and cTnI ≥ 0.07 ng/mL (OR 8.74, 95% CI 5.881–12.987, P < 0.001) remained significantly and independently associated with MACE after the adjustment of the confounding factors. Kaplan-Meier event-free survival curves demonstrated that patients with preoperative simultaneous NT-proBNP level > 917 pg/mL and cTnT ≥0.07 ng/mL had worse event-free survival than individual assessments of either biomarker.

Conclusion

Preoperative plasma NT-proBNP and cTnI are both independently associated with an increased risk of MACE in elderly patients after emergent non-cardiac surgery. The combination of these biomarkers provides better prognostic information than using either biomarker separately.

Three-dimensional computed tomography angiography for the preoperative evaluation of coronary artery disease in lung cancer patients

BACKGROUND

The number of elderly patients undergoing surgery for lung cancer is increasing. In this study, we assessed the usefulness of three-dimensional computed tomographicangiography (3D-CTA) for the detection of coronary disease in the elderly before surgical intervention for lung cancer.

METHODS

One hundred twenty patients admitted to our institution for lung cancer resection were enrolled in the study. 3D-CTA was performed in all 120 patients.

RESULTS

Seventy-one patients had normal findings, and forty-nine patients showed coronary stenosis on 3D-CTA examination. Among the latter 49 patients, 24 with slight stenosis underwent lung tumor resection, 23 had coronary angiography for severe stenosis before lung surgery and 2 were not eligible for lung resection because of very severe coronary stenosis. The diagnostic value of 3D-CTA was better than conventional CT.

CONCLUSIONS

This study suggests the usefulness of 3D-CTA for the preoperative diagnosis of coronary ischemic disease in elderly lung cancer patients.

Cardiac injury and troponin testing after orthopaedic surgery

BACKGROUND

Cardiac injury after orthopaedic surgery is an increasing problem particularly in an ageing population. The detection of cardiac injury has been aided by the use of cardiac troponins which has also raised questions about the utility of this enzyme in the post-operative setting.

OBJECTIVE

This review evaluates the diagnosis and pathophysiology of myocardial infarction after orthopaedic surgery and examines how myocardial injury is detected, with particular emphasis on the role of troponin testing.

SUBJECTS

Eight recent orthopaedic trials evaluating the use of troponin were identified in the literature and included in this review.

RESULTS

This review found that the diagnosis of myocardial infarction ismore difficult after surgery since classic symptoms may be atypical or absent. Therefore, there ismore reliance on the typical rise and fall in troponin to diagnose cardiac injury especially because electrocardiograph changes may be hard to detect. The pathophysiology of ischaemia after orthopaedic surgery may be different to ischaemia in the non-surgical setting. The incidence of troponin elevation is between 22 and 52.9% after emergency orthopaedic operations. Of note, patients sustaining a troponin elevation are often asymptomatic. Small studies have found troponin to be a prognostic marker of in-hospital cardiac complications, increased length of stay, increased likelihood of discharge to residential care and death at 1 year. No interventional studies have been published to date.

CONCLUSION

Cardiac injury is an important complication after orthopaedic surgery. Studies have found that troponin testing can detect asymptomatic cardiac injury. These patients are at risk of poorer outcomes and future research should be directed towards treatment of these patients.

Treatment recommendations to prevent myocardial ischemia and infarction in patients undergoing vascular surgery

During major vascular surgery (MVS), patients are at high risk for developing unrecognized myocardial infarction (MI) and myocardial ischemia. In reducing postoperative morbidity and mortality, preoperative cardiac risk stratification and adequate medical therapy play a pivotal role. Based on literature and current opinions, medical treatment should comprise at least a combination of beta-blockers, aspirin, and statins. beta-Blockers exert their beneficial effects predominantly through heart rate control, leading to reduced oxygen demand during surgery. A heart rate between 65 and 70 bpm should be achieved. Irrespective of their lipid-lowering effects, statins seem to improve postoperative cardiac outcome by stabilizing coronary artery plaques, thereby preventing atherosclerotic plaque rupture. Aspirin reduces platelet activation and vasoconstriction, thereby limiting ischemic events and reducing nonfatal MI by 34%. Adding clopidogrel to low-dose aspirin might be beneficial toward postoperative cardiac outcomes; however, the effect on the incidence of postoperative bleeding complications may be a problem for future studies to resolve. Whereas beta-blockers inhibit the effect of catecholamines, alpha(2)-agonists inhibit catecholamine release and may be used in the perioperative setting when beta-blockers are contraindicated. Despite the blood pressure-lowering effect and anti-inflammatory properties of angiotensin-converting enzyme inhibitors, the literature does not support their use in patients undergoing MVS. The possible use of calcium antagonists before MVS should be further evaluated in high-risk patients with contraindications to beta-blockers, such as asthma, conduction abnormalities, or a history of stroke. Although nitrates are widely used for treating angina pectoris, the beneficial effect of their use in patients undergoing MVS remains controversial. Therefore, nitrates are not routinely used in the perioperative setting. The current American College of Cardiology/American Heart Association guidelines do not recommend prophylactic coronary revascularization before noncardiac surgery in patients with stable coronary artery disease.

Usefulness of N-terminal pro-brain natriuretic peptide to predict postoperative cardiac complications and long-term mortality after emergency lower limb orthopedic surgery

After emergency orthopedic-geriatric surgery, cardiac complications are an important cause of morbidity and mortality. The utility of N-terminal pro-brain natriuretic peptide (NT-pro-BNP) for the prediction of cardiac complications and mortality was evaluated. NT-pro-BNP was tested pre- and postoperatively in 89 patients >60 years of age. They were followed for 2 years for cardiac complications (defined as acute myocardial infarction, congestive cardiac failure, atrial fibrillation or major arrhythmia) or death. Receiver operating characteristic curves were constructed to determine the optimal discriminatory level for cardiac events and death using NT-pro-BNP. Twenty-three patients (25.8%) sustained an in-hospital postoperative cardiac complication. Total all-cause mortality was 3 of 89 (3.4%) in hospital, 21 of 89 (23.6%) at 1 year, and 27 of 89 (30.3%) at 2 years. Median preoperative and postoperative NT-pro-BNP levels were higher in patients who had an in-hospital cardiac event compared to those without (387 vs 1,969 pg/ml, p <0.001; and 676 vs 7,052 pg/ml, p <0.001 respectively). The optimal discriminatory level for preoperative NT-pro-BNP was 842 pg/ml and that for postoperative NT-pro-BNP was 1,401 pg/ml for the prediction of in-hospital cardiac events and 1- and 2-year mortality. Preoperative NT-pro-BNP >/=842 pg/ml (odds ratio 11.6, 95% confidence interval 2.1 to 65.0, p = 0.005) was an independent predictor of in-hospital cardiac complications using multivariate analysis and pre- and postoperative NT-pro-BNP levels were independent predictors of 2-year cardiovascular events. Patients who had preoperative NT-pro-BNP >/=842 pg/ml or postoperative NT-pro-BNP >/=1,401 pg/ml had significantly worse survival using log-rank testing (p <0.001) and these variables independently predicted 2-year mortality. In conclusion, increase pre- and postoperative NT-pro-BNP levels are independent predictors of in-hospital cardiac events and 1- and 2-year mortality in older patients undergoing emergency orthopedic surgery.