Coronary artery plaque burden and perioperative cardiac risk

Existing Nongated CT Coronary Calcium Predicts Operative Risk in Patients Undergoing Noncardiac Surgeries (ENCORES)

BACKGROUND

Preoperative cardiovascular risk stratification before noncardiac surgery is a common clinical challenge. Coronary artery calcium scores from ECG-gated chest computed tomography (CT) imaging are associated with perioperative events. At the time of preoperative evaluation, many patients will not have had ECG-gated CT imaging, but will have had nongated chest CT studies performed for a variety of noncardiac indications. We evaluated relationships between coronary calcium severity estimated from previous nongated chest CT imaging and perioperative major clinical events (MCE) after noncardiac surgery.

METHODS

We retrospectively identified consecutive adults age ≥45 years who underwent in-hospital, major noncardiac surgery from 2016 to 2020 at a large academic health system composed of 4 acute care centers. All patients had nongated (contrast or noncontrast) chest CT imaging performed within 1 year before surgery. Coronary calcium in each vessel was retrospectively graded from absent to severe using a 0 to 3 scale (absent, mild, moderate, severe) by physicians blinded to clinical data. The estimated coronary calcium burden (ECCB) was computed as the sum of scores for each coronary artery (0 to 9 scale). A Revised Cardiac Risk Index was calculated for each patient. Perioperative MCE was defined as all-cause death or myocardial infarction within 30 days of surgery.

RESULTS

A total of 2554 patients (median age, 68 years; 49.7% women; median Revised Cardiac Risk Index, 1) were included. The median time interval from nongated chest CT imaging to noncardiac surgery was 15 days (interquartile range, 3-106 days). The median ECCB was 1 (interquartile range, 0-3). Perioperative MCE occurred in 136 (5.2%) patients. Higher ECCB values were associated with stepwise increases in perioperative MCE (0: 2.9%, 1-2: 3.7%, 3-5: 8.0%; 6-9: 12.6%, P<0.001). Addition of ECCB to a model with the Revised Cardiac Risk Index improved the C-statistic for MCE (from 0.675 to 0.712, P=0.018), with a net reclassification improvement of 0.428 (95% CI, 0.254-0.601, P<0.0001). An ECCB ≥3 was associated with 2-fold higher adjusted odds of MCE versus an ECCB <3 (adjusted odds ratio, 2.11 [95% CI, 1.42-3.12]).

CONCLUSIONS

Prevalence and severity of coronary calcium obtained from existing nongated chest CT imaging improve preoperative clinical risk stratification before noncardiac surgery.

Computed tomographic coronary angiography in risk stratification prior to non-cardiac surgery: a systematic review and meta-analysis

OBJECTIVES

Utility of CT coronary angiography (CTA) and coronary artery calcium (CAC) scoring in risk stratification prior to non-cardiac surgery is unclear. Although current guidelines recommend stress testing in intermediate-high risk individuals, over one-third of perioperative major adverse cardiovascular events (MACE) occur in patients with a negative study. This systematic review and meta-analysis evaluates the value of CTA and CAC score in preoperative risk prognostication prior to non-cardiac surgery.

METHODS

MEDLINE, PubMed and EMBASE databases were searched for articles published up to June 2018. Summary ORs for degree of coronary artery disease (CAD) and perioperative MACE were pooled using a random-effects model.

RESULTS

Eleven studies were included. Two hundred and fifty-two (7.2%) MACE occurred in 3480 patients. Risk of perioperative MACE rose with the severity and extent of CAD on CTA (no CAD 2.0%; non-obstructive 4.1%; obstructive single-vessel 7.1%; obstructive multivessel 23.1%, p<0.001). Multivessel disease (MVD) demonstrated the greatest risk (OR 8.9, 95% CI 5.1 to 15.3, p<0.001). Increasing CAC score was associated with higher perioperative MACE (CAC score: ≥100 OR 5.1, ≥1000 OR 10.4, both p<0.01). In a cohort deemed high risk by established clinical indices, absence of MVD on CTA demonstrated a negative predictive value of 96% (95% CI 92.8 to 98.4) for predicting freedom from MACE.

CONCLUSIONS

Severity and extent of CAD on CTA conferred incremental risk for perioperative MACE in patients undergoing non-cardiac surgery. The 'rule-out' capability of CTA is comparable to other non-invasive imaging modalities and offers a viable alternative for risk stratification of patients undergoing non-cardiac surgery.

TRIAL REGISTRATION NUMBER

CRD42018100883.

The use of bispectral index monitoring in education - a tool to improve nurse-anaesthetists practice

AIM

This paper is a report of a study to investigate whether monitoring depth of anaesthesia by bispectral index would reduce recovery time and consumption of anaesthetic drugs in anaesthetics performed by student nurse-anaesthetists.

BACKGROUND

It is difficult to assess the depth of anaesthesia clinically. Studies have shown that experienced anaesthetists can titrate anaesthetics more accurately when using bispectral index monitors. It is not known if student nurse-anaesthetists can benefit from their use in a similar way.

METHOD

A multicentre study involving four hospitals was carried out during a 13-month period in 2003 and 2004. In total 25 nurses participated, each contributing with two procedures: one with monitoring and one without. The nurses had at least 10 months of experience in conducting anaesthesia and all had a theoretical introduction and a test session to become familiar with the equipment. The sequence was randomized and the observer was blinded to whether a monitor was used. Fifty patients were anaesthetized with propofol and fentanyl. Recovery time, consumption of anaesthetic drugs, and patient satisfaction were measured in both groups.

RESULTS

Recovery time was 11 minutes in the monitor group (range: 2-53 minutes) and 15 minutes in the control group, (range: 3-60 minutes). P = 0.26. There were no statistically significant differences in consumption of anaesthetic drugs or patient satisfaction in the two groups.

CONCLUSION

It was not possible to demonstrate a statistically significant reduction in recovery time or consumption of anaesthetic drugs when using bispectral index monitoring during training of student nurse-anaesthetists.

Methods of detecting atherosclerosis in non-cardiac surgical patients; the role of biochemical markers

Atherosclerosis is a common condition in both the developed and developing world and is now recognised to be an inflammatory condition leading to the development of ischaemic heart disease, cerebrovascular disease and peripheral vascular disease. Ischaemic heart disease is a major risk factor in the pathogenesis of perioperative adverse cardiovascular events which lead to significant morbidity and mortality within the high risk surgical patient population. Current methods of evaluating the likelihood of postoperative cardiovascular complications depend largely on risk scoring systems, and the preoperative assessment of the functional status of the cardiovascular system. However, the possible role of inflammation in the generation of atherosclerosis has led to the identification of several biochemical markers such as acute phase proteins, cellular adhesion molecules and cytokines. An alternative approach therefore is the measurement of preoperative levels of these biomarkers with the aim of assessing pre-existing disease activity. This review summarises the pathophysiology of atherosclerosis and perioperative myocardial infarction, and discusses the possible future role of biomarkers in the risk stratification of patients undergoing non-cardiac surgery.

Review article: The role of statins in reducing perioperative cardiac risk: physiologic and clinical perspectives

PURPOSE

To review the pathobiology and clinical implications of coronary vulnerable atherosclerotic plaques (VAPs), to discuss the role of statin therapy in VAP stabilization, and the potential benefits of perioperative statin therapy (PST) in reducing perioperative risk of acute coronary syndromes (ACSs).

SOURCE

MEDLINE search using "perioperative", "cardiac morbidity", "atherosclerosis", "vulnerable plaque", "statins" and combinations of these terms as keywords. The reference lists of relevant articles were further reviewed to identify additional citations.

PRINCIPAL FINDINGS

The nonstenotic, yet rupture-prone VAP causes most myocardial infarctions (MIs) and other ACSs, both in the nonsurgical and surgical patients. Large clinical trials in both primary and secondary prevention and in patients with ACSs have demonstrated that statin therapy will reduce cardiovascular morbidity and mortality across a broad spectrum of patient subgroups. These trials also suggest, and laboratory investigations establish, that statins possess favourable vascular effects independent of cholesterol reduction. Statins appear to interfere specifically with the pathophysiologic mechanisms implicated in atherothrombotic disease. Statins reduce vascular inflammation, improve endothelial function, stabilize VAPs, and reduce platelet aggregability and thrombus formation. Recent studies have shown that PST is associated with a reduced incidence of perioperative and long-term cardiovascular complications in high-risk patients. Combined therapy with statins and ss-blockers is a conceptually valid strategy targeting critical steps in the pathogenesis of an ACS.

CONCLUSION

Emerging evidence for the efficacy and safety of PST is promising, especially when combined with ss-blocker therapy in patients at highest risk. Confirmation of this early evidence awaits the results of ongoing and future prospective randomized controlled trials.