Critical Appraisal of Cardiac Risk Stratification Before Elective Vascular Surgery

Role of cardiac evaluation before thoracic endovascular aortic repair

BACKGROUND

Patients with thoracic aortic disease undergoing thoracic endovascular aortic repair (TEVAR) often have concomitant coronary artery disease and are at risk for perioperative adverse cardiac events. Despite this risk, the need for and extent of preoperative cardiac workup before TEVAR remain undefined. This study seeks to assess the adequacy of a limited cardiac evaluation before TEVAR, including assessment of cardiac symptoms, resting electrocardiography (ECG), and transthoracic echocardiography (TTE), as well as to estimate the incidence of perioperative cardiac events in patients undergoing TEVAR.

METHODS

Retrospective analysis of a prospectively maintained Institutional Review Board-approved database was performed for all patients undergoing TEVAR at a single referral institution between May 2002 and June 2013. The analysis identified 463 TEVAR procedures. All procedures involving median sternotomy were excluded, and 380 procedures (343 patients) were included in the final analysis. Degree of cardiac workup was classified on the basis of the highest level of preoperative testing: no workup, resting ECG only, resting TTE, exercise/pharmacologic stress testing, or coronary angiography. Standard workup consisted of cardiac symptom assessment along with resting ECG or TTE, with further workup indicated for unstable symptoms, significantly abnormal findings on ECG or TTE, or multiple cardiac risk factors. Categorical and continuous variables were compared by Fisher's exact test and analysis of variance, respectively.

RESULTS

No preoperative cardiac workup was performed for 28 patients (7.4%); 127 patients (33.4%) had resting ECG only, 208 patients (54.7%) had resting echocardiography, 12 patients (3.2%) underwent stress testing, and five patients (1.3%) had coronary angiography. Patients undergoing stress testing or coronary angiography were older and had a higher incidence of known coronary artery disease (P < .01) and prior myocardial infarction (P = .01). Complex hybrid aortic repairs and TEVAR for aneurysmal disease were more likely to have an extensive workup, whereas nonelective procedures more commonly had no workup. A total of nine patients (2.4%) experienced a perioperative cardiac event (myocardial infarction or cardiac arrest), with no significant difference noted among all groups (P = .45), suggesting that the extent of cardiac workup was appropriate. The incidence of 30-day/in-hospital mortality (5.5%) and cardiac-specific mortality (0.8%) was similar among all groups.

CONCLUSIONS

The risk of a postoperative cardiac event after TEVAR is low (2.4%), and initial screening with either resting TTE or ECG, in addition to assessment of cardiac symptom status, appears adequate for most TEVAR patients. As such, we recommend resting TTE or ECG as the initial cardiovascular screening mechanism in patients undergoing TEVAR, with subsequent more invasive studies if initial screening reveals cardiovascular abnormalities.

Does the presence of coronary artery disease impact perioperative outcomes following partial hepatectomy?

INTRODUCTION

Coronary artery disease (CAD) is often considered a contraindication to hepatectomy despite a lack of data to support this practice. The purpose of this study is to evaluate the impact of CAD on postoperative outcomes in patients undergoing hepatectomy.

MATERIAL AND METHODS

A total of 1,206 consecutive patients undergoing hepatectomy from August 1995 to June 2009 were included. Propensity matching was performed to identify differences in morbidity and mortality between patients with and without CAD. Subgroup analyses were performed to stratify patients based on the severity of CAD and the interval between coronary intervention and hepatectomy.

RESULTS

Of all patients, 138 (11.4%) had a diagnosis of CAD and were more likely to have a malignant diagnosis and other comorbid conditions including renal insufficiency, COPD, and diabetes. Matched patients with CAD had no significant differences in complication rates, with 2.2 and 5.8% of CAD patients experiencing a postoperative myocardial infarction or arrhythmia, respectively. Propensity matching failed to identify differences in mortality or morbidity. Subgroup analysis revealed similar rates of mortality and complications regardless of the severity of CAD or the time interval between coronary intervention and hepatectomy.

CONCLUSION

Despite the increased prevalence of major medical comorbidities, selected patients with CAD can safely undergo hepatectomy with acceptable rates of postoperative morbidity and mortality.

Nanosensor electrical immunoassay for quantitative detection of NT-pro brain natriuretic peptide

AIM

To demonstrate a label-free electrical immunoassay for profiling vascular biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP) associated with improved cardiac risk prediction.

MATERIALS & METHODS

A high-density nanowell-based electrical immunoassay has been designed by integrating nanoporous aluminum oxide onto printed circuit board chips for the detection of NT-proBNP. The concentration of the biomarker is quantitatively determined by measuring impedance changes to the electrical double layer within the nanowells using electrochemical impedance spectroscopy. Detection sensitivity in the fg/ml range was obtained due to spatial confinement of the target biomarkers in size-matched nanowells.

RESULTS & DISCUSSION

Electrical immunoassay performance was determined for the detection of NT-proBNP in phosphate-buffered saline (PBS) and human serum (HS). The lower limit of detection for the sensor was observed to be 10 fg/ml in PBS and 500 fg/ml in HS. The upper limit of detection was observed to be 500 fg/ml in PBS and 500 ng/ml in HS.

CONCLUSION

A label-free technique for detection of NT-proBNP at clinically relevant concentrations for evaluating cardiac risk is demonstrated. High sensitivity and specificity, robust detection and low volume (100 µl) per assay project the technology to be a successful competitor to traditional ELISA-based techniques.

Major lower extremity amputation in elderly patients with peripheral arterial disease: incidence and survival rates

BACKGROUND AND AIMS

The methods of treating peripheral arterial disease (PAD) have changed and become more prophylactic. This study describes and analyzes 1) the incidence rates of major lower extremity amputation (LEA) due to PAD, 2) occurrence of re-amputation, and 3) the survival of amputees and factors predicting survival.

METHODS

The series consisted of 210 patients (mean age 76.6, SD 10.7 yrs, 45.2% men) who underwent their first, i.e. index, major leg amputation because of PAD, in 1998-2002, in the city of Turku, Finland, population 175,000.

RESULTS

The age-and gender-standardized incidence rate of combined above-knee and below-knee amputations was 24.1/100,000 person-years during 1998-2002. Thirty-four per cent of amputees underwent repetitive amputation. One-month mortality was 21% (n=45), one-year mortality 52% (n=109) and overall mortality 80% (n=168). Cardiovascular diseases predicted equally well 31-day, one-year, and overall mortality in age- and gender- adjusted analysis. Multiple co-morbidities (p=0.023) and unilateral above-knee amputations (p=0.047) were significant predictors for overall mortality in age- and gender-adjusted analysis. Cardiovascular diseases remained a significant predictor for 31-day and overall mortality in multivariate analysis (p=0.008 and p=0.015, respectively). Amputated patients' previous vascular procedures did not have any effect on mortality in the Cox model. Most revascularizations were performed less than six months before the index/first major LEA.

CONCLUSION

Major LEAs seem to have been done late, and mainly for pain relief in the end-stage of patients with peripheral arterial disease.

American College of Cardiology/American Heart Association perioperative assessment guidelines for noncardiac surgery reduces cardiologic resource utilization preserving a favourable clinical outcome

OBJECTIVES

The American College of Cardiology (ACC) and the American Heart Association (AHA) provided perioperative evaluation and management guidelines for assessing cardiac risk in noncardiac surgery. Even if previously validated as safe and effective in risk stratification, there is often a gap between clinical practice and the recommendations of the ACC/AHA guidelines. We evaluated the impact of strict application of ACC/AHA guidelines for cardiac risk assessment of patients undergoing elective noncardiac vascular surgery in a consultant anaesthesiologist-led preoperative clinic.

METHODS

One hundred and sixty-four consecutive patients who underwent elective vascular surgery after ACC/AHA guidelines implementation (from September 2004 to May 2005) were enrolled in the study and compared with a historical group of 166 patients operated from April 2002 to September 2002. Preoperative resources utilization (cardiologic consultations, non-invasive diagnostic tests, coronary angiograms, coronary revascularizations) and clinical events [all-cause death, acute myocardial infarction (AMI) and acute myocardial ischaemia] occurring within 30 days after surgical procedure were compared.

RESULTS

Guidelines implementation reduced preoperative cardiologic consultations by 21% (P < 0.001) and preoperative non-invasive diagnostic testing by 11% (P = 0.01), and increased utilization of preoperative beta-blockers by 13% (P = 0.01). Preoperative coronary angiograms (2% versus 4%) and coronary revascularizations (3% versus 2%) and all-cause death (1% versus 2%), AMI (2% versus 1%) and acute myocardial ischaemia (4% versus 2%) during follow-up were similar in both groups.

CONCLUSIONS

Implementation of the ACC/AHA guidelines for cardiac risk assessment prior to noncardiac surgery in a consultant anaesthesiologist-led preoperative clinic reduced preoperative resources utilization, improved medical treatment and preserved a low rate of perioperative cardiac complications.

Myocardial infarction in major noncardiac surgery: Epidemiology, pathophysiology and prevention

The number of subjects undergoing major noncardiac surgery who are at risk for perioperative myocardial infarction (MI) is growing worldwide.

It has been estimated that 500,000 to 900,000 patients suffer major perioperative cardiovascular complications every year, with consequent heavy, long-term prognostic implications and costs.

It is well known that perioperative MIs don’t share the same pathophysiology as nonsurgical MIs but the relative role of the different, potential triggers has not been completely clarified.

Many aspects of the perioperative management, including risk-stratification and prophylactic or postoperative interventions have also not been completely defined.

Throughout recent years many resources have been invested to clarify these aspects and experts have developed indices and algorithm-based strategies to better assess the cardiac risk and to guide the perioperative management.

The scope of the present review is to discuss the main aspects of perioperative MI in noncardiac surgery, with particular regard to epidemiology, pathophysiology, preoperative risk stratification, prophylaxis and therapy.

Vascular surgery critical care: perioperative cardiac optimization to improve survival

OBJECTIVE

To review the literature on perioperative cardiac management of patients who are scheduled to undergo vascular surgery.

DATA SOURCE

MEDLINE- and PubMed-based review of literature published from 1965 to 2005.

CONCLUSIONS

Perioperative cardiac events (myocardial infarction, heart failure) remain the leading cause of morbidity and mortality in vascular surgery patients. Existing guidelines allow physicians to cost-effectively streamline preoperative cardiac risk assessment and stratification. Perioperative optimization of volume status and cardiac function and the routine use of perioperative beta-blockers can significantly improve outcomes after major vascular surgery. Perioperative addition of statins to beta-blockers in high-risk patients undergoing vascular surgery merits further evaluation. Preoperative coronary revascularization should be restricted to patients with unstable cardiac symptoms.

Cardiac surgery in the elderly: indications and management options to optimize outcomes

The elderly have increasingly benefited from the advances in cardiac surgical techniques and perioperative care. Compared to the same procedures in younger patients their operations can be more technically demanding and their level of reserve leaves less margin should complications occur. The importance of using realistic indications for operations with a focus on improving the quality of their lives and of optimal preoperative preparation of patients is emphasized.

ACC/AHA guidelines for preoperative cardiovascular evaluation for noncardiac surgery: a critical point of view

This review examines the issue of preoperative cardiac evaluation from a critical point of view, based on recent medical literature. We reviewed the history of that field and focused on the American College of Cardiology and American Heart Association guidelines, which are a cornerstone in the field of cardiac patients undergoing noncardiac surgery. These guidelines synthesized the data into a comprehensive format and established the concept of integrating the patient's risk with the surgical risk. Nevertheless, there are some weaknesses in the guidelines. We believe that a better understanding of the guideline limitations will allow an improved and more educated practice of its recommendations.

Clinician agreement with perioperative cardiovascular evaluation guidelines and clinical outcomes

The American College of Cardiology/American Heart Association (ACC/AHA) published guidelines for preoperative cardiac risk stratification in 1996. Although clinician practice may differ from the guidelines, it remains unclear whether deviation from these guidelines affects clinical outcomes. This study sought to determine if discordance between clinician practice and the ACC/AHA guidelines affects perioperative cardiac outcomes. Eight hundred twenty-three patients who underwent 864 consecutive preoperative evaluations performed from 1995 to 1997 at a tertiary care academic medical center were prospectively followed. Clinician recommendations for preoperative cardiac testing were compared with ACC/AHA guideline recommendations. Frequencies of perioperative cardiac complications were compared between concordant and discordant testing recommendations. There were 33 perioperative cardiac complications (3.8%). Overall, there was no difference in the frequency of complications when there was discordance with the ACC/AHA guidelines compared with concordance (4.1% vs 3.7%, p = 0.81). The ACC/AHA guidelines recommended cardiac testing for 236 patients (27.3%). Clinicians ordered testing in half of those cases (n = 112). There was a lower frequency of cardiac complications when clinicians did not perform testing as recommended by the ACC/AHA guidelines (3.2% vs 10.7%, p = 0.02). Conversely, clinicians ordered cardiac testing in 45 patients (7%) when not recommended by the guidelines. Patients in this group had a trend toward more cardiac complications (6.7% vs 2.4%, p = 0.09). In conclusion, the failure of clinicians to follow the ACC/AHA guidelines when perioperative testing was recommended did not result in a higher frequency of cardiac complications.

Perioperative cardiac events in patients undergoing noncardiac surgery: a review of the magnitude of the problem, the pathophysiology of the events and methods to estimate and communicate risk

This is the first of 2 articles evaluating cardiac events in patients undergoing noncardiac surgery. In this article, we review the magnitude of the problem, the pathophysiology of these events, approaches to risk assessment and communication of risk. The number of patients undergoing noncardiac surgery worldwide is growing, and annually 500,000 to 900,000 of these patients experience perioperative cardiac death, nonfatal myocardial infarction (MI) or nonfatal cardiac arrest. Although the evidence is limited, a substantial proportion of fatal perioperative MIs may not share the same pathophysiology as nonoperative MIs. A clearer understanding of the pathophysiology is needed to direct future research evaluating prophylactic, acute and long-term interventions. Researchers have developed tools to facilitate the estimation of perioperative cardiac risk. Studies suggest that the Lee index is the most accurate generic perioperative cardiac risk index. The limitations of the studies evaluating the ability of noninvasive cardiac tests to predict perioperative cardiac risk reveals considerable uncertainty as to the role of these popular tests. Similarly, there is uncertainty as to the predictive accuracy of the American College of Cardiology/American Heart Association algorithm for cardiac risk assessment. Patients are likely to benefit from improved estimation and communication of cardiac risk because the majority of noncardiac surgeries are elective and accurate risk estimation is important to allow informed patient and physician decision-making.

Preoperative cardiac evaluation does not improve or predict perioperative or late survival in asymptomatic diabetic patients undergoing elective infrainguinal arterial reconstruction

OBJECTIVE

Patients undergoing infrainguinal arterial reconstruction frequently have increased cardiac risk factors. Diabetic patients are often asymptomatic despite advanced cardiac disease. This study investigates whether preoperative cardiac testing improves the outcome in diabetic patients at risk for cardiac disease.

METHODS

We retrospectively reviewed all patients undergoing lower-extremity arterial reconstructions in a 32-month period from July 1999 to February 2002. Of the 433 patients identified undergoing 539 procedures, 295 had diabetes mellitus and considered in this study. The patients were stratified into two groups according to the present American College of Cardiology, American Heart Association (ACC/AHA) algorithm. We identified 140 patients with two or more of ACC (Eagle) criteria who met the inclusion criteria for a preoperative cardiac evaluation. These patients were separated into two groups: those undergoing a cardiac work-up (WU) according to the ACC/AHA algorithm and those not undergoing the recommended work-up (NWU). Outcomes included perioperative mortality, postoperative myocardial infarction, congestive heart failure, arrhythmia, and length of hospitalization. Significance of association was assessed by the Fisher exact test. Length of hospitalization was compared using the Kruskal-Wallis rank sum test. Survival data was analyzed with the Kaplan-Meier method.

RESULTS

One hundred forty patients met the criteria for moderate risk. There were 61 patients in the NWU group and 79 in the WU group. Ten patients in the WU group underwent preoperative coronary revascularization (6 had percutaneous transluminal coronary angioplasty, 4 underwent coronary artery bypass grafting). There was no difference between perioperative mortality (WU, 1%; NWU, 2%; P = 1.00) or in postoperative cardiac morbidity, including myocardial infarction, congestive heart failure, and arrhythmia requiring treatment (WU, 5%; NWU, 6%; P = .71). There were no perioperative deaths and one episode of congestive heart failure in the group that had preoperative coronary revascularization. Median length of hospitalization was 10 days in the WU group and 8 days in the NWU group ( P = .11). Patient survival at 12 months for the NWU, WU, and revascularized groups was 85.3%, 78.5%, and 80.0%, respectively; 36-month survival was 73.6%, 62.9%, and 80.0%, respectively. The three survival curves did not differ significantly ( P = .209).

CONCLUSIONS

Preoperative cardiac evaluation, as defined by the ACC/AHA algorithm, does not predict or improve postoperative morbidity, mortality, or 36-month survival in asymptomatic, diabetic patients undergoing elective lower-extremity arterial reconstruction. These data do not support the current ACC/AHA recommendations as a standard of care for diabetic patients with an intermediate clinical predictor who undergo peripheral arterial reconstruction, a high-risk surgical procedure.

Strategies in the high-risk cardiac patient undergoing non-cardiac surgery

The risk of perioperative myocardial infarction or cardiac death in patients undergoing non-cardiac surgery may be estimated by clinical risk factor analysis and by myocardial stress testing. While stress testing modalities accurately delineate reversible myocardial ischaemia, their positive predictive value is low, and it is not clear whether their implementation improves outcome when compared to risk stratification alone. Similarly, it remains to be shown that preoperative coronary revascularization is an effective strategy in reducing perioperative risk. Recent reports indicate that surgery undertaken in the first weeks after percutaneous coronary interventions may be associated with a significantly increased rate of major complications. Administration of beta-blockers and alpha2-adrenergic agonists to high-risk patients reduces surgical morbidity and mortality, and the benefits observed with beta-blockers may extend long after the operative period. In high-risk patients undergoing major surgery, pulmonary artery catheter-guided haemodynamic optimization has not been associated with better outcomes, whereas use of regional anesthetic techniques decreases the incidence of postoperative pulmonary, but not cardiac, complications.

Long-term survival after vascular surgery: Specific influence of cardiac factors and implications for preoperative evaluation

OBJECTIVE

We sought to identify specific determinants of long-term cardiac events and survival in patients undergoing major arterial operations after preoperative cardiac risk stratification by American College of Cardiology/American Heart Association guidelines. A secondary goal was to define the potential long-term protective effect of previous coronary revascularization (coronary artery bypass grafting [CABG] or percutaneous coronary intervention [PCI]) in patients with vascular disease.

METHODS

Four hundred fifty-nine patients underwent risk stratification (high, intermediate, low) before 534 consecutive elective or urgent (<24 hours after presentation) open cerebrovascular, aortic, or lower limb reconstruction procedures between August 1996 and January 2000. Long-term follow-up (mean, 56 +/- 14 months) was possible in 97% of patients. The Kaplan-Meier method was used for survival data. Long-term prognostic variables were identified with the multivariate Cox proportional hazards model and contingency table analysis censoring early (<30 days) perioperative deaths.

RESULTS

While 5-year survival was 72% for the overall cohort, cardiac causes accounted for only 24% of all deaths, and new cardiac events (myocardial infarction, congestive heart failure, arrhythmia, unstable angina, new coronary angiography, new CABG or PCI, cardiac death) affected only 4.6% of patients per year during follow-up. High cardiac risk stratification level (hazards ratio [HR], 2.2, 95% confidence interval [CI], 1.4-3.4), adverse perioperative cardiac events (myocardial infarction, congestive heart failure, ventricular arrhythmia; HR, 2.2; 95% CI, 1.2-4.1), and age (HR, 0.33; 95% CI, 0.2-0.6) were independently prognostic for latemortality. Preoperative cardiac risk levels also correlated with new cardiac event rates ( P < .01) and late cardiac mortality ( P = .02). Modestly improved survival in patients who had undergone CABG or PCI less than 5 years before vascular operations compared with those who had undergone revascularization 5 or more years previously and those at high risk without previous coronary intervention (73% vs 58% vs 62% 5-year survival; P = .02) could be demonstrated with univariate testing, but not with multivariate analysis. Type of operation, urgency, noncardiac complications, and presence of diabetes did not affect long-term survival.

CONCLUSION

Despite cardiac events being a less common cause of late mortality after vascular surgery, perioperative cardiac factors (age, preoperative risk level, early cardiac complications) are the primary determinants of patient longevity. Patients undergoing more recent (<5 years) CABG or PCI before vascular surgery do not have an obvious survival advantage compared with patients at high cardiac risk without previous coronary interventions.