Importance of long-duration postoperative ST-segment depression in cardiac morbidity after vascular surgery

The Significance of Equipment Availability and Anesthesia Educational Conferences to Decision-Making for EKG Lead V5 Abnormalities

Introduction To predict postoperative myocardial infarction rates in patients who undergo noncardiac surgery, the Canadian Cardiovascular Society Guidelines on Perioperative Cardiac Risk Assessment and Management recommends assessment of brain natriuretic peptide (BNP) in certain patients. Serial troponins are measured if the BNP level is elevated. In certain cases, Revised Cardiac Risk Index (RCRI) alone does not perform well, for example, during vascular surgery. Cardiac events occur in 20% of all vascular surgery patients. The odds ratio for such events is 9.2 if ST segments were depressed by 1 mm intraoperatively (relative to the PR interval) within the first 48 hours postoperatively. Increasing the number of cables and pads from three to five for electrocardiogram (EKG) increases the sensitivity from around 30% to over 80% for ischemic events relative to a formal EKG stress test, and then the monitor continuously displays not only lead II but also lead V5. Methods Our hypothesis was that raising awareness about diagnostic and therapeutic options to reduce the risk of postoperative myocardial infarction would increase the use of five pads. We conducted open-ended surveys at six hospitals to assess the reasons for choosing three pads. In our university hospital practice, we measured a cross-sectional incidence of using three pads before and, once again, a month after an intervention during a single morning. Several resident conferences encouraged the use of five pads. Education included weekly lectures and informal discussions with other staff during surgery, demonstrating that using five pads allows interrogation of an entire 12-lead EKG. In comparison, three pads only allow viewing three leads. Results At baseline, only three pads were available in 96% of our 23 operating rooms. Five cables were available in eight of those surgeries, but two were taped off to the side. Surveys unveiled scarcity of equipment and, more importantly, disempowerment (i.e., knowing how to diagnose or when to treat ischemia). After several conferences, the prevalence of equipment availability of only three pads fell to 47%. Conclusions Education enumerated details of recognizing ischemic configurations of ST depression. Next, education revealed methods to interrupt the progression of ischemia to infarction such as elevated blood pressure and hematocrit, reducing heart rate, and calling a cardiology consultant if the anesthesiologist wishes to draw serial troponins. Barriers to implementing an enhanced recovery after surgery (ERAS) pathway began with a need for more access to manage stress tests or optimize blood pressure medications after a preoperative anesthesia evaluation. The intraoperative barrier was knowing what to do if ST depression occurs. Therefore, we began raising awareness by encouraging the addition of an element of a future ERAS pathway, adding a cost of only $1 to monitor lead V5. Future ERAS pathways can include preoperative stress tests and consults, as found in published guidelines.

Disease Mechanisms of Perioperative Organ Injury

Despite substantial advances in anesthesia safety within the past decades, perioperative mortality remains a prevalent problem and can be considered among the top causes of death worldwide. Acute organ failure is a major risk factor of morbidity and mortality in surgical patients and develops primarily as a consequence of a dysregulated inflammatory response and insufficient tissue perfusion. Neurological dysfunction, myocardial ischemia, acute kidney injury, respiratory failure, intestinal dysfunction, and hepatic impairment are among the most serious complications impacting patient outcome and recovery. Pre-, intra-, and postoperative arrangements, such as enhanced recovery after surgery programs, can contribute to lowering the occurrence of organ dysfunction, and mortality rates have improved with the advent of specialized intensive care units and advances in procedures relating to extracorporeal organ support. However, no specific pharmacological therapies have proven effective in the prevention or reversal of perioperative organ injury. Therefore, understanding the underlying mechanisms of organ dysfunction is essential to identify novel treatment strategies to improve perioperative care and outcomes for surgical patients. This review focuses on recent knowledge of pathophysiological and molecular pathways leading to perioperative organ injury. Additionally, we highlight potential therapeutic targets relevant to the network of events that occur in clinical settings with organ failure.

Cardiac risk assessment for end-stage renal disease patients on the renal transplant waiting list

Cardiovascular disease is a leading cause of morbidity and mortality and is becoming more prevalent as the population ages and risk factors increase. This is most apparent in the end-stage renal disease (ESRD) patient population. In part, this is due to cofactors such as diabetes and hypertension commonly predisposing to progressive renal disease, as well as being a direct consequence of having renal failure. Of all major organ failures, kidney failure is the most likely to be managed chronically using renal replacement therapy and, ultimately, transplant. However, lack of transplant organs and a large renal failure cohort means waiting lists are often quite long and may extend to 5-10 years. Due to the cardiac risk factors inherent in patients awaiting transplant, many succumb to cardiac issues while waiting and present an increased per-procedural cardiac risk that extends into the post-transplant period. We aim to review the epidemiology of coronary artery disease in this population and the etiology as it relates to ESRD and its associated co-factors. We also will review the current approaches, recommendations and evidence for management of these patients as it relates to transplant waiting lists before and after the surgery. Recommendations on how to best manage patients in this cohort revolve around the available evidence and are best customized to the institution and the structure of the program. It is not clear whether the revascularization of patients without symptoms and with a good functional status yields any improvement in outcomes. Therefore, each individual case should be considered based on the risk factors, symptoms and functional status, and approached as part of a multi-disciplinary assessment program.

[Perioperative lumbar plexus block and cardiac ischemia in patients with hip fracture: randomized clinical trial]

BACKGROUND

Perioperative myocardial ischemia is common among patients undergoing hip fracture surgery. Our aim is to evaluate the efficacy of perioperative continuous lumbar plexus block in reducing the risk of cardiac ischemic events of elderly patients undergoing surgery for hip fractures, expressed as a reduction of ischemic events per subject.

METHODS

Patients older than 60 years, ASA II-III, with risk factors for or known coronary artery disease were enrolled in this randomized controlled study. Patients were randomized to conventional analgesia using opioid intravenous patient-controlled analgesia or continuous lumbar plexus block analgesia, both started preoperatively and maintained until postoperative day three. Continuous electrocardiogram monitoring with ST segment analysis was recorded. Serial cardiac enzymes and pain scores were registered during the entire period. We measured the incidence of ischemic events per subject registered by a continuous ST-segment Holter monitoring.

RESULTS

Thirty-one patients (intravenous patient-controlled analgesia 14, lumbar plexus 17) were enrolled. There were no major cardiac events during the observation period. The number of ischemic events recorded by subject during the observation period was 6 in the lumbar plexus group and 3 in the intravenous patient-controlled analgesia group. This difference was not statistically significant (p=0.618). There were no statistically significant differences in the number of cases with increased perioperative troponin values (3 cases in the lumbar plexus group and 1 case in the intravenous patient-controlled analgesia group) or in terms of pain scores.

CONCLUSIONS

Using continuous perineural analgesia, compared with conventional systemic analgesia, does not modify the incidence of perioperative cardiac ischemic events of elderly patients with hip fracture.

Etiology of Acute Coronary Syndrome after Noncardiac Surgery

BACKGROUND

The objective of this investigation was to determine the etiology of perioperative acute coronary syndrome with a particular emphasis on thrombosis versus demand ischemia.

METHODS

In this retrospective cohort study, adult patients were identified who underwent coronary angiography for acute coronary syndrome within 30 days of noncardiac surgery at a major tertiary hospital between January 2008 and July 2015. Angiograms were independently reviewed by two interventional cardiologists who were blinded to clinical data and outcomes. Acute coronary syndrome was classified as ST-elevation myocardial infarction, non-ST-elevation myocardial infarction, or unstable angina; myocardial infarctions were adjudicated as type 1 (plaque rupture), type 2 (demand ischemia), or type 4b (stent thrombosis).

RESULTS

Among 215,077 patients screened, 146 patients were identified who developed acute coronary syndrome: 117 were classified as non-ST-elevation myocardial infarction (80.1%); 21 (14.4%) were classified as ST-elevation myocardial infarction, and 8 (5.5%) were classified as unstable angina. After coronary angiography, most events were adjudicated as demand ischemia (type 2 myocardial infarction, n = 106, 72.6%) compared to acute coronary thrombosis (type 1 myocardial infarction, n = 37, 25.3%) and stent thrombosis (type 4B, n = 3, 2.1%). Absent or only mild, nonobstructive coronary artery disease was found in 39 patients (26.7%). In 14 patients (9.6%), acute coronary syndrome was likely due to stress-induced cardiomyopathy. Aggregate 30-day and 1-yr mortality rates were 7 and 14%, respectively.

CONCLUSIONS

The dominant mechanism of perioperative acute coronary syndrome in our cohort was demand ischemia. A subset of patients had no evidence of obstructive coronary artery disease, but findings were consistent with stress-induced cardiomyopathy.

Associations Between Cardiac Troponin, Mechanism of Myocardial Injury, and Long-Term Mortality After Noncardiac Vascular Surgery

BACKGROUND

The time-sensitive hazard of perioperative cardiac troponin T (cTnT) elevation and whether long-term mortality differs by mechanism of myocardial injury are poorly understood.

METHODS AND RESULTS

In this observational study of 12 882 patients who underwent noncardiac vascular surgery, patients were assessed for cTnT sampling within 96 hours postoperatively. Mortality out to 5-years was stratified by cTnT level and mechanism of myocardial injury. During a median follow-up of 26.9 months, there were 2149 (16.7%) deaths. By multivariable Cox proportional hazards analysis, there was a graded increase in mortality with any detectable cTnT compared to <0.01 ng/mL; cTnT 0.01 to 0.029 ng/mL hazard ratio (HR) 1.54 (95% CI 1.18-2.00, P=0.002), 0.03 to 0.099 ng/mL HR 1.86 (95% CI 1.49-2.31, P<0.001), 0.10 to 0.399 ng/mL HR 1.83 (95% CI 1.46-2.31, P<0.001), ≥0.40 ng/mL HR 2.62 (95% CI 2.06-3.32, P<0.001). Mortality for each mechanism of injury was greater than for patients with normal cTnT; baseline cTnT elevation HR 1.71 (95% CI 1.31-2.24; P<0.001), Type 2 myocardial infarction HR 1.88 (95% CI 1.57-2.24; P<0.001), Type 1 MI HR 2.56 (95% CI 2.56, 1.82-3.60; P<0.001). On Kaplan-Meier analysis, long-term survival did not differ between mechanisms. The hazard of mortality was greatest within the first 10 months postsurgery. Consistent results were obtained in confirmatory propensity-score matched analyses.

CONCLUSIONS

Any detectable cTnT ≥0.01 ng/mL is associated with increased long-term mortality after vascular surgery. This risk is greatest within the first 10 months postoperatively. While short-term mortality is greatest with Type 1 myocardial infarction, long-term mortality appears independent of the mechanism of injury.

The patient with ischaemic heart disease undergoing non cardiac surgery

The incidence of ischaemic heart disease (IHD) is increasing. The patients with IHD with or without interventions coming for non-cardiac surgical procedures are also increasing. These patients have increased risk of myocardial ischaemia, myocardial infarction (MI), conduction disturbances, morbidity and mortality during the peri-operative period. The risks of these events are even higher in patients with recent MI. An anaesthesiologist should be aware of the pathophysiology and the need to thoroughly evaluate the patient for peri-operative management. We searched Pubmed using combinations of terms like “ischemic heart disease” and “anaesthesia”, “perioperative”, and “anaesthetic implications”. We reviewed the current practices and guidelines regarding evaluation, risk stratification and management.

Postoperative Cardiac Ischemia Detection by Continuous 12-Lead Electrocardiographic Monitoring in Vascular Surgery Patients: A Prospective, Observational Study

OBJECTIVES

Elderly patients undergoing vascular surgery are at major risk for perioperative cardiac complications. The authors investigated continuous electrocardiographic Holter monitoring in a postoperative setting to determine the degree of postoperative ischemic load and its possible associations with perioperative myocardial infarction.

DESIGN

A prospective, observational study.

SETTING

One university hospital.

PARTICIPANTS

The study comprised 51 patients aged 65 years or older undergoing peripheral arterial surgery.

INTERVENTIONS

Continuous electrocardiographic monitoring with a Holter device was started postoperatively and continued for 72 hours or until discharge. Postural changes were recorded using a 3-axis accelerometer. Standard 12-lead electrocardiography, high-sensitive troponin T measurements, and an inquiry of ischemic symptoms were performed 4 times perioperatively.

MEASUREMENTS AND MAIN RESULTS

The primary outcomes were ischemic load (area under the function of ischemic ST-segment deviation and ischemic time) and perioperative myocardial infarction. During 3,262.7 patient-hours of monitoring, 17 patients (33.3%) experienced 608 transient ischemic events, all denoted by ST-segment depression. Of these 17 patients, 5 experienced perioperative myocardial infarction. The mean ischemic load in all patients was 913.2±2,797.3 µV×minute. Ischemic load predicted perioperative myocardial infarction, with an area under receiver operating characteristics curve (95% confidence interval) of 0.87 (0.75-0.99). Ischemic changes occurred most frequently during hours 24 to 60 of monitoring. Ischemia was asymptomatic in 14 of 17 patients (82.4%).

CONCLUSION

Postoperative myocardial ischemia was common in peripheral vascular surgery patients and may progress to perioperative myocardial infarction. Ischemic load was a good predictor of perioperative myocardial infarction. Ambulatory electrocardiographic monitoring solutions for continuous postoperative ischemia detection are warranted in the surgical ward.

Canadian Cardiovascular Society Guidelines on Perioperative Cardiac Risk Assessment and Management for Patients Who Undergo Noncardiac Surgery

The Canadian Cardiovascular Society Guidelines Committee and key Canadian opinion leaders believed there was a need for up to date guidelines that used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system of evidence assessment for patients who undergo noncardiac surgery. Strong recommendations included: 1) measuring brain natriuretic peptide (BNP) or N-terminal fragment of proBNP (NT-proBNP) before surgery to enhance perioperative cardiac risk estimation in patients who are 65 years of age or older, are 45-64 years of age with significant cardiovascular disease, or have a Revised Cardiac Risk Index score ≥ 1; 2) against performing preoperative resting echocardiography, coronary computed tomography angiography, exercise or cardiopulmonary exercise testing, or pharmacological stress echocardiography or radionuclide imaging to enhance perioperative cardiac risk estimation; 3) against the initiation or continuation of acetylsalicylic acid for the prevention of perioperative cardiac events, except in patients with a recent coronary artery stent or who will undergo carotid endarterectomy; 4) against α₂ agonist or β-blocker initiation within 24 hours before surgery; 5) withholding angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker starting 24 hours before surgery; 6) facilitating smoking cessation before surgery; 7) measuring daily troponin for 48 to 72 hours after surgery in patients with an elevated NT-proBNP/BNP measurement before surgery or if there is no NT-proBNP/BNP measurement before surgery, in those who have a Revised Cardiac Risk Index score ≥1, age 45-64 years with significant cardiovascular disease, or age 65 years or older; and 8) initiating of long-term acetylsalicylic acid and statin therapy in patients who suffer myocardial injury/infarction after surgery.

Signal Quality Analysis of Ambulatory Electrocardiograms to Gate False Myocardial Ischemia Alarms

OBJECTIVE

The objective of this study is to propose and validate an alarm gating system for a myocardial ischemia monitoring system that uses ambulatory electrocardiogram. The PeriOperative ISchemic Evaluation study recommended the selective administration of β blockers to patients at risk of cardiac events following noncardiac surgery. Patients at risk are identified by monitoring ST segment deviations in the electrocardiogram (ECG); however, patients are encouraged to ambulate to improve recovery, which deteriorates the signal quality of the ECG leading to false alarms.

METHODS

The proposed alarm gating system computes a signal quality index (SQI) to quantify the ECG signal quality and rejects alarms with a low SQI. The system was validated by artificially contaminating ECG records with motion artifact records obtained from the long-term ST database and MIT-BIH noise stress test database, respectively.

RESULTS

Without alarm gating, the myocardial ischemia monitoring system attained a Precision of 0.31 and a Recall of 0.78. The alarm gating improved the Precision to 0.58 with a reduction of Recall to 0.77.

CONCLUSION

The proposed system successfully gated false alarms with future work exploring the misidentification of fiducial points by myocardial ischemia monitoring systems.

SIGNIFICANCE

The reduction of false alarms due to the proposed system will decrease the incidence of the alarm fatigue condition typically found in clinicians. Alarm fatigue condition was rated as the top patient safety hazard from 2012 to 2015 by the Emergency Care Research Institute.

Diagnosing Perioperative Myocardial Infarction in Cardioth oracic and Vascular Surgery

Patients undergoing cardiac and high-risk noncardiac surgery have a high incidence of perioperative myocardial infarction. The early diagnosis of perioperative myocardial injury in these patients is complicated. In the perioperative period, there is a high incidence of nonspecific electrocardiographic changes and cardiac biomarker release. It is becoming increasingly imortant to differentiate myocardial necrosis from nonspecific changes because of the need for early intervention and the poential long term implications of a perioperative myocardial event. Although sensitive and specific assays to assess myoardial damage have been developed, specific thresholds to establish the occurrence a significant perioperative event have not been firmly defined. This review will attempt to outline the current evidence supporting the use of clinical symptoms, electrocardiographic changes, and cardiac biomarkers in the diagnosis of perioperative myocardial infarction and the longerm implication of these findings.

Technology-Enabled Remote Monitoring and Self-Management - Vision for Patient Empowerment Following Cardiac and Vascular Surgery: User Testing and Randomized Controlled Trial Protocol

Background

Tens of thousands of cardiac and vascular surgeries (CaVS) are performed on seniors in Canada and the United Kingdom each year to improve survival, relieve disease symptoms, and improve health-related quality of life (HRQL). However, chronic postsurgical pain (CPSP), undetected or delayed detection of hemodynamic compromise, complications, and related poor functional status are major problems for substantial numbers of patients during the recovery process. To tackle this problem, we aim to refine and test the effectiveness of an eHealth-enabled service delivery intervention, TecHnology-Enabled remote monitoring and Self-MAnagemenT—VIsion for patient EmpoWerment following Cardiac and VasculaR surgery (THE SMArTVIEW, CoVeRed), which combines remote monitoring, education, and self-management training to optimize recovery outcomes and experience of seniors undergoing CaVS in Canada and the United Kingdom.

Objective

Our objectives are to (1) refine SMArTVIEW via high-fidelity user testing and (2) examine the effectiveness of SMArTVIEW via a randomized controlled trial (RCT).

Methods

CaVS patients and clinicians will engage in two cycles of focus groups and usability testing at each site; feedback will be elicited about expectations and experience of SMArTVIEW, in context. The data will be used to refine the SMArTVIEW eHealth delivery program. Upon transfer to the surgical ward (ie, post-intensive care unit [ICU]), 256 CaVS patients will be reassessed postoperatively and randomly allocated via an interactive Web randomization system to the intervention group or usual care. The SMArTVIEW intervention will run from surgical ward day 2 until 8 weeks following surgery. Outcome assessments will occur on postoperative day 30; at week 8; and at 3, 6, 9, and 12 months. The primary outcome is worst postop pain intensity upon movement in the previous 24 hours (Brief Pain Inventory-Short Form), averaged across the previous 14 days. Secondary outcomes include a composite of postoperative complications related to hemodynamic compromise—death, myocardial infarction, and nonfatal stroke— all-cause mortality and surgical site infections, functional status (Medical Outcomes Study Short Form-12), depressive symptoms (Geriatric Depression Scale), health service utilization-related costs (health service utilization data from the Institute for Clinical Evaluative Sciences data repository), and patient-level cost of recovery (Ambulatory Home Care Record). A linear mixed model will be used to assess the effects of the intervention on the primary outcome, with an a priori contrast of weekly average worst pain intensity upon movement to evaluate the primary endpoint of pain at 8 weeks postoperation. We will also examine the incremental cost of the intervention compared to usual care using a regression model to estimate the difference in expected health care costs between groups.

Results

Study start-up is underway and usability testing is scheduled to begin in the fall of 2016.

Conclusions

Given our experience, dedicated industry partners, and related RCT infrastructure, we are confident we can make a lasting contribution to improving the care of seniors who undergo CaVS.

Prolonged elevated heart rate is a risk factor for adverse cardiac events and poor outcome after subarachnoid hemorrhage

INTRODUCTION

Sympathetic nervous system hyperactivity is common after subarachnoid hemorrhage (SAH). We sought to determine whether uncontrolled prolonged heart rate elevation is a risk factor for adverse cardiopulmonary events and poor outcome after SAH.

METHODS

We prospectively studied 447 SAH patients between March 2006 and April 2012. Prior studies define prolonged elevated heart rate (PEHR) as heart rate >95 beats/min for >12 h. Major adverse cardiopulmonary events were documented according to the predefined criteria. Global outcome at 3 months was assessed with the modified Rankin Scale (mRS).

RESULTS

175 (39 %) patients experienced PEHR. Nonwhite race/ethnicity, admission Hunt-Hess grade ≥4, elevated APACHE-2 physiological subscore, and modified Fisher score were significant admission predictors of PEHR, whereas documented pre-hospital beta-blocker use was protective. After controlling for admission Hunt-Hess grade, Cox regression using time-lagged covariates revealed that PEHR onset in the previous 48 h was associated with an increased hazard for delayed cerebral ischemia, myocardial injury, and pulmonary edema. PEHR was associated with 3-month poor outcome (mRS 4-6) after controlling for known predictors.

CONCLUSIONS

PEHR is associated with major adverse cardiopulmonary events and poor outcome after SAH. Further study is warranted to determine if early sympatholytic therapy targeted at sustained heart rate control can improve outcome after SAH.

Non-cardiac surgery after percutaneous coronary intervention

Perioperative management of patients after percutaneous coronary intervention presents physicians with unique challenges and dilemmas. Although newer generation drug-eluting stents, transcatheter-based therapies, and minimally invasive surgical techniques have changed the medical landscape, guidelines for managing perioperative patients after percutaneous intervention are based largely on expert opinion and inconsistent data from an earlier era. In conclusion, the aims of this review are to summarize the data pertinent to managing patients after percutaneous coronary intervention in the perioperative period and to explore future perspectives.

Perioperative cardiovascular complications versus perioperative bleeding in consecutive patients with known cardiac disease undergoing non-cardiac surgery. Focus on antithrombotic medication. The PRAGUE-14 registry

Background

Interruption of antithrombotic treatment before surgery may prevent bleeding, but at the price of increasing cardiovascular complications. This prospective study analysed the impact of antithrombotic therapy interruption on outcomes in non-selected surgical patients with known cardiovascular disease (CVD).

Methods

All 1200 consecutive patients (age 74.2 ± 10.2 years) undergoing major non-cardiac surgery (37.4 % acute, 61.4 % elective) during a period of 2.5 years while having at least one CVD were enrolled. Details on medication, bleeding, cardiovascular complications and cause of death were registered.

Results

In-hospital mortality was 3.9 % (versus 0.9 % mortality among 17,740 patients without CVD). Cardiovascular complications occurred in 91 (7.6 %) patients (with 37.4 % case fatality). Perioperative bleeding occurred in 160 (13.3 %) patients and was fatal in 2 (1.2 % case fatality). Multivariate analysis revealed age, preoperative anaemia, history of chronic heart failure, acute surgery and general anaesthesia predictive of cardiovascular complications. For bleeding complications multivariate analysis found warfarin use in the last 3 days, history of hypertension and general anaesthesia as independent predictive factors. Aspirin interruption before surgery was not predictive for either cardiovascular or for bleeding complications.

Conclusions

Perioperative cardiovascular complications in these high-risk elderly all-comer surgical patients with known cardiovascular disease are relatively rare, but once they occur, the case fatality is high. Perioperative bleeding complications are more frequent, but their case fatality is extremely low. Patterns of interruption of chronic aspirin therapy before major non-cardiac surgery are not predictive for perioperative complications (neither cardiovascular, nor bleeding). Simple baseline clinical factors are better predictors of outcomes than antithrombotic drug interruption patterns.

Use of ivabradine and atorvastatin in emergent orthopedic lower limb surgery and computed tomography coronary plaque imaging and novel biomarkers of cardiovascular stress and lipid metabolism for the study and prevention of perioperative myocardial infarction: study protocol for a randomized controlled trial

Background

The incidence of perioperative myocardial infarction (PMI) globally is known to be around 2 to 3% and can prolong hospitalization, increased morbidity and mortality. Little is known about the pathophysiology and risk factors for PMI. We investigate the presence of elevated novel cardiac markers and preoperative coronary artery plaque through contemporary laboratory techniques to determine the correlation with PMI, as well as studying ivabradine and atorvastatin as protective pharmacotherapies against PMI in the context of orthopedic surgery.

Methods/Design

We aim to enroll 200 patients aged above 60 years who suffer from neck of femur fracture requiring surgery. Patients will be randomized to four arms (no study drugs, atorvastatin only, ivabradine only and ivabradine and atorvastatin). Our primary outcome is incidence of PMI. All patients will receive an electrocardiogram, cardiac echocardiography, measurement of novel cardiac biomarkers and computed tomography (CT) coronary angiography. A telephone interview post discharge will be conducted at 30 days, 60 days and 1 year.

Discussion

We postulate that ivabradine and atorvastatin will reduce the rate and magnitude of PMI following surgery by reducing heart rate and attenuating catecholamine-induced tachycardia postoperatively. Secondly, we postulate that postoperative reduction in heart rate and catecholamine-induced tachycardia with ivabradine will correlate with a reduction in cardiovascular novel biomarkers which will reduce atrial stretch and postoperative incidence of arrhythmia. We aim to demonstrate that treatment with ivabradine and atorvastatin will cause a reduction in the incidence and magnitude of PMI, the benefit of which is derived primarily in patients with greater atherosclerotic burden as measured by higher CT coronary calcium scores.

Trial registration

This study protocol has been listed in the Australia New Zealand Clinical Trial Registry (registration number: ACTRN12612000340831) on 23 March 2012.

Ivabradine: potential clinical applications in critically ill patients

It has been extensively demonstrated that an elevated heart rate is a modifiable, independent risk factor for cardiovascular events. A high heart rate increases myocardial oxygen consumption and reduces diastolic perfusion time. It can also increase ventricular diastolic pressures and induce ventricular arrhythmias. Critical care patients are prone to develop a stress induced cardiac impairment and consequently an increase in sympathetic tone. This in turn increases heart rate. In this setting, however, heart rate lowering might be difficult because the effects of inotropic drugs could be hindered by heart rate reducing drugs like beta-blockers. Ivabradine is a new selective antagonist of funny channels. It lowers heart rate, reducing the diastolic depolarization slope. Moreover, ivabradine is not active on sympathetic pathways, thus avoiding any interference with inotropic amines. We reviewed the literature available regarding heart rate control in critical care patients, focusing our interest on the use of ivabradine to assess the potential benefits of the drug in this particular setting.

Recurrent intraoperative silent ST depression responding to phenylephrine

Intraoperative myocardial ischemia is attributed to decreased myocardial oxygen supply. We present an unusual case of recurrent, symptomless inferior wall ischemia in an apparently healthy male with no history of coronary artery disease after a spinal block. The recurring episodes were linked to tachycardia and presented with significant ST depression in Lead II with reciprocal elevation in lead aVL. The episodes responded to phenylephrine and subsided without residual sequelae.

Randomized comparison of sevoflurane versus propofol to reduce perioperative myocardial ischemia in patients undergoing noncardiac surgery

BACKGROUND

Volatile anesthetics provide myocardial preconditioning in coronary surgery patients. We hypothesized that sevoflurane compared with propofol reduces the incidence of myocardial ischemia in patients undergoing major noncardiac surgery.

METHODS AND RESULTS

We enrolled 385 patients at cardiovascular risk in 3 centers. Patients were randomized to maintenance of anesthesia with sevoflurane or propofol. We recorded continuous ECG for 48 hours perioperatively, measured troponin T and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) on postoperative days 1 and 2, and evaluated postoperative delirium by the Confusion Assessment Method. At 6 and 12 months, we contacted patients by telephone to assess major adverse cardiac events. The primary end point was a composite of myocardial ischemia detected by continuous ECG and/or troponin elevation. Additional end points were postoperative NT-proBNP concentrations, major adverse cardiac events, and delirium. Patients and outcome assessors were blinded. We tested dichotomous end points by χ(2) test and NT-proBNP by Mann-Whitney test on an intention-to-treat basis. Myocardial ischemia occurred in 75 patients (40.8%) in the sevoflurane and 81 (40.3%) in the propofol group (relative risk, 1.01; 95% confidence interval, 0.78-1.30). NT-proBNP release did not differ across allocation on postoperative day 1 or 2. Within 12 months, 14 patients (7.6%) suffered a major adverse cardiac event after sevoflurane and 17 (8.5%) after propofol (relative risk, 0.90; 95% confidence interval, 0.44-1.83). The incidence of delirium did not differ (11.4% versus 14.4%; P=0.379).

CONCLUSIONS

Compared with propofol, sevoflurane did not reduce the incidence of myocardial ischemia in high-risk patients undergoing major noncardiac surgery. The sevoflurane and propofol groups did not differ in postoperative NT-proBNP release, major adverse cardiac events at 1 year, or delirium.

Cardioprotective effect of sevoflurane in patients with coronary artery disease undergoing vascular surgery

OBJECTIVES

The present study was conducted to evaluate the cardioprotective effect of sevoflurane compared with propofol in patients with coronary artery disease (CAD) undergoing peripheral vascular surgery; and to address the question whether a volatile anesthetic might improve cardiac outcome in these patients.

METHODS

One hundred twenty-six patients scheduled for elective peripheral vascular surgery were prospectively randomized to receive either sevoflurane inhalation anesthesia or total intravenous anesthesia. ST-segment monitoring was performed continuously during intra- and post-operative 48 h periods. The number of ischemic events and the cumulative duration of ischemia in each patient were recorded. Blood was sampled in all patients for the determination of cTnI. Samples were obtained before the induction of anesthesia, on admission to the ICU, and at 6, 12, 24, and 48 h after admission to the intensive care unit (ICU). Patients were followed-up during their hospital stay for any adverse cardiac events.

RESULTS

The incidence of ischemia were comparable among the groups [16 (25%) patients in sevoflurane group vs 24 (39%) patients in propofol group; P=0.126]. Duration, cumulative duration, and magnitude of ST-segment depression of ischemic events in each patient were significantly less in sevoflurane group (P=0.008, 0.048, 0.038, respectively). cTnI levels of the overall population were significantly less in sevoflurane group vs propofol group (P values <0.0001) from 6 h postoperative and onward. Meanwhile, cTnI levels at 6, 12, 24, and 48 h after admission to the ICU in patients who presented with ischemic electrocardiographic (ECG) changes were significantly lower in sevoflurane group than in the propofol group (P<0.0001, <0.0001, <0.0001, 0.0003). None of the patients presented with unstable angina, myocardial infarction, congestive heart failure, or serious arrhythmia either during ICU or hospital stay.

CONCLUSION

Patients with CAD receiving sevoflurane for peripheral vascular surgery had significantly lower release of cardiac troponin I at 6 h postoperatively and lasting for 48 h than patients receiving propofol for the same procedure with significant decrease in duration, cumulative duration of ischemic events, and degree of ST depression in each patient.

Is Peri-Operative Isolated Systolic Hypertension (ISH) a Cardiac Risk Factor?

We are presenting a review of Isolated Systolic Hypertension (ISH) as a cardiovascular risk factor with emphasis on the perioperative period.

Isolated systolic hypertension is associated with aging and is the most frequent subtype (65%) among patients with uncontrolled hypertension. ISH is strongly associated with increased risks of cardiac and cerebrovascular events exceeding those in comparably aged individuals with diastolic hypertension. Patients with ISH show an increase in left ventricular (LV) mass and an increase in the prevalence of left ventricular hypertrophy (LVH). These LV changes increase cardiovascular events and frequently lead to diastolic dysfunction (DD). Treatment to reduce elevated systolic blood pressure has been shown to reduce the risk of cardiovascular events.

In the perioperative setting, essential hypertension has not been found to be a significant risk factor for cardiac complications. Most of the studies were based on the definition of essential hypertension and underpowered in sample size. The significance of perioperative ISH, however, is not well studied, partly due to its recognition only fairly recently as a cardiovascular risk factor in the non-surgical setting, and partly due to the evolving definition of ISH.

Perioperative cardiac complications remain a significant problem to the healthcare system and to the patient. Although the incidence of perioperative cardiac complications is prominent in high-risk patients as defined by the Revised Cardiac Risk Index (RCRI), the bulk of the cardiac complications actually occur in low-risk group. Currently, little understanding exists on the occurrence of perioperative cardiac complications in low- risk patients. A factor such as ISH, with its known pathophysiological changes, is a potential perioperative risk factor.

We believe ISH is an under-recognized perioperative risk factor and deserves further studying. Our research group has recently been funded by the Heart Stroke Foundation (HSF) to examine ISH as a perioperative risk factor (PROMISE Study).

Continuous ST-segment monitoring in the intensive care unit

This article provides evidence-based rationales to substantiate revisions of current monitoring practices and to provide realistic strategies for implementation of new practices.

Perioperative myocardial ischemia and isolated systolic hypertension in non-cardiac surgery

PURPOSE

To determine whether patients with isolated systolic hypertension (ISH) undergoing non-cardiac surgery have a higher incidence of perioperative myocardial ischemia than normotensive patients and hence a greater risk for perioperative adverse events.

METHODS

After obtaining Research Ethics Board approval, patients were recruited to either an ISH group (systolic blood pressure [SBP] > 140 mmHg with diastolic blood pressure [DBP] < 90 mmHg) or a normotensive group (SBP < 140 mmHg and DBP < 90 mmHg), according to their resting preoperative blood pressure. The primary outcome was the overall incidence of perioperative myocardial ischemia (PMI) as determined by 48-hr ambulatory Holter monitoring. P values ≤ 0.05 were considered to be statistically significant.

RESULTS

A total of 312 (150 ISH and 162 normotensive) patients completed the study. Orthopedic surgery was the most frequent surgical procedure in both groups. The overall incidence of PMI was 19.7% in the ISH group compared with 18.8% in the normotensive group (difference 0.9%; 95% confidence interval [CI], -7.9% to 9.8%). The overall incidence of adverse events was 4.0% in the ISH group compared with 1.9% in the normotensive group (difference 2.2%; 95% CI, -1.6% to 5.9%).

CONCLUSION

In this study, we chose to examine ISH as potential cardiac risk factor for patients undergoing non-cardiac surgery. The incidence of myocardial ischemia, a surrogate outcome, was similar in the two groups. The relatively high incidence of myocardial ischemia (19.2%) was of particular interest in this relatively low cardiac risk surgical population. (ClinicalTrials.gov number, NCT01237652).

Acute, fatal postoperative myocardial infarction after laparoscopic cholecystectomy in a cardiac patient -A case report-

This report presents the case of a 63-year-old man who had a myocardial infarction leading to coronary artery bypass graft 2 years earlier who subsequently underwent elective laparoscopic cholecystectomy. After an uneventful operation, the patient developed an acute postoperative myocardial infarction in the recovery room and died 19 days postoperatively. Anesthesiologists should be aware of the rare possibility of acute, fatal postoperative myocardial infarction and consider this complication when they perform the preoperative risk evaluation, anesthesia, and postoperative care for cardiac patients undergoing noncardiac surgery.

Impact of transfusion policy on acute coronary syndrome after major vascular reconstruction

OBJECTIVES

To investigate the impact of a restrictive transfusion approach, as indicated by accepting a perioperative hemoglobin (Hb) level as low as 8 g/dL, on the incidence of acute coronary syndrome (ACS) and mortality after major vascular reconstruction.

METHODS

Using a case-control design, 45 patients who underwent vascular reconstruction and developed postoperative ACS were compared with 135 patients treated with similar procedures who did not suffer ACS postoperatively.

RESULTS

A history of CAD was more often present in the ACS group (16% vs 56%) and was an independent predictor of ACS (odds ratio [OR] = 6.62; confidence interval [CI], 3.16-13.88; P < .001) and postoperative death (OR = 5.08; CI, 2.0-12.85; P = .001). Postoperative (Hb) levels as low as 8 g/dL were well tolerated and had no impact on the occurrence of ACS (OR = .61; CI, 0.29-1.26; P = .181) or death (OR = 1.33; CI, 0.52-3.43; P = .547). The presence of CAD for a given Hb level did not increase the odds of either ACS (OR = 3.43; CI, .75-15.6; P = .112) or death (OR = 2.02; CI, .5-19.55; P = .543).

CONCLUSIONS

A restrictive transfusion policy is justified in patients undergoing major vascular reconstruction, even in the presence of appropriately managed cad.

Skilled Cardiac Monitoring at the Bedside: An Algorithm for Success

The ECG lead monitoring algorithm was developed to provide a tool to assist bedside nurses in monitoring ST segments and dysrhythmias.

The pathophysiology of peri-operative myocardial infarction

SUMMARY

It is generally believed that plaque rupture and myocardial oxygen supply-demand imbalance contribute approximately equally to the burden of peri-operative myocardial infarction. This review critically analyses data of post-mortem, pre-operative coronary angiography, troponin surveillance, other pre-operative non-invasive investigations, and peri-operative haemodynamic predictors of myocardial ischaemia and/or myocardial infarction. The current evidence suggests that myocardial oxygen supply-demand imbalance predominates in the early postoperative period. It is likely that flow stagnation and thrombus formation is an important pathway in the development of a peri-operative myocardial infarction, in addition to the more commonly recognised role of peri-operative tachycardia. Research and therapeutic interventions should be focused on the prediction and therapy of flow stagnation and thrombus formation. Plaque rupture appears to be a more random event, distributed over the entire peri-operative admission.

Perioperative cardiac damage in vascular surgery patients

BACKGROUND

Patients undergoing vascular surgery are at increased risk for developing cardiac complications. Majority of patients with perioperative myocardial damage are asymptomatic. Our objective is to review the available literature addressing the prevalence and prognostic implications of perioperative myocardial damage in vascular surgery patients.

METHODS

An Internet-based literature search was performed using MEDLINE to identify all published reports on perioperative myocardial damage in vascular surgery patients. Only those studies published from 2000 to 2010 evaluating myocardial damage using troponin I or T, with or without symptoms of angina pectoris were included.

RESULTS

Thirteen studies evaluating the prevalence of perioperative myocardial ischaemia or infarction were included in the study. The incidence of perioperative myocardial ischaemia ranged from 14% to 47% and the incidence of perioperative myocardial infarction ranged from 1% to 26%. In addition, 10 studies evaluating the prognostic value of perioperative myocardial ischaemia towards postoperative mortality or the occurrence of major adverse cardiac events were included. In the retrieved studies, hazard ratios varied from 1.9 to 9.0.

CONCLUSION

The high prevalence and asymptomatic nature of perioperative myocardial damage, combined with a substantial influence on postoperative mortality of vascular surgery patients, underline the importance of early detection and adequate management of perioperative myocardial damage. This article provides an extended overview regarding the prevalence and prognostic value of perioperative myocardial ischaemia and infarction in vascular surgery patients. In addition, treatment options to reduce the risk of perioperative myocardial damage are provided based on the current available literature.