Low utility of dobutamine stress echocardiograms in the preoperative evaluation of patients scheduled for noncardiac surgery

Preoperative Cardiac Stress Tests Ordered in the Preoperative Evaluation Clinic: A Retrospective Review of Ordering Patterns

Background

The role of anesthesiologists has expanded from operating rooms to preoperative evaluation clinics. This role involves performing preoperative cardiovascular evaluation and optimization of patients before elective surgery, which can include ordering cardiac stress tests. We aimed to study the ordering patterns by anesthesiologists for preoperative cardiac stress tests, focusing on whether societal and institutional guidelines and recommendations were used. Choice of type of cardiac stress test was also examined.

Methods

A single center retrospective chart review from December 1, 2005 to May 31, 2015 was performed on 492 patients who had a cardiac stress test ordered by an anesthesiologist. Patients were categorized by indication for ordering the cardiac stress test based on societal practice guidelines, institutional guidelines or other relevant reasons at the time of patient encounter. Those “other” category cardiac stress tests were assessed for indication and evaluated by physician peer review to see if there was peer agreement for being appropriately ordered. Exercise electrocardiography (ECG) cardiac stress tests ordered were evaluated for appropriateness based on baseline resting ECG findings. Patients with left bundle branch block (LBBB) or right ventricular (RV) pacing were evaluated for appropriateness of proper cardiac stress test modality based on whether a pharmacological vasodilator cardiac stress test was ordered.

Results

Analysis of the cardiac stress tests ordered showed that 43% were ordered according to American College of Cardiology/American Heart Association guidelines, 29% were ordered according to institutional guidelines, and 28% were categorized as “other”. Of the 28% “other” cardiac stress tests, 53% were in agreement for ordering by peer review. Sixty-four exercise ECG cardiac stress tests were ordered, of which 58% were appropriate based on having no baseline resting ECG abnormalities. Fifty-one patients were identified as having a resting ECG of LBBB or RV pacing of which 41% had an appropriate pharmacological vasodilator cardiac stress tests ordered.

Conclusions

Anesthesiologists order most preoperative cardiac stress tests according to professional societal or institutional guidelines (72%), yet they are not always choosing the best modality of cardiac stress test. A significant portion of cardiac stress tests are ordered (28%) based on clinical judgment, likely due to the lack of guidelines and recommendations being all-encompassing on many commonly encountered preoperative patient situations.

The association of preoperative cardiac stress testing with 30-day death and myocardial infarction among patients undergoing kidney transplantation

BACKGROUND

Although periodic cardiac stress testing is commonly used to screen patients on the waiting list for kidney transplantation for ischemic heart disease, there is little evidence to support this practice. We hypothesized that cardiac stress testing in the 18 months prior to kidney transplantation would not reduce postoperative death, total myocardial infarction (MI) or fatal MI.

METHODS

Using the United States Renal Data System, we identified ESRD patients ≥40 years old with primary Medicare insurance who received their first kidney transplant between 7/1/2006 and 11/31/2013. Propensity matching created a 1:1 matched sample of patients with and without stress testing in the 18 months prior to kidney transplantation. The outcomes of interest were death, total (fatal and nonfatal) MI or fatal MI within 30 days of kidney transplantation.

RESULTS

In the propensity-matched cohort of 17,304 patients, death within 30 days occurred in 72 of 8,652 (0.83%) patients who underwent stress testing and in 65 of 8,652 (0.75%) patients who did not (OR 1.07; 95% CI: 0.79-1.45; P = 0.66). MI within 30 days occurred in 339 (3.9%) patients who had a stress test and in 333 (3.8%) patients who did not (OR 1.03; 95% CI: 0.89-1.21; P = 0.68). Fatal MI occurred in 17 (0.20%) patients who underwent stress testing and 15 (0.17%) patients who did not (OR 0.97; 95% CI: 0.71-1.32; P = 0.84).

CONCLUSION

Stress testing in the 18 months prior to kidney transplantation is not associated with a reduction in death, total MI or fatal MI within 30 days of kidney transplantation.

Nuclear Myocardial Perfusion Imaging Versus Stress Echocardiography in the Preoperative Evaluation of Patients for Kidney Transplantation

The goal of this study was to evaluate the diagnostic accuracy, cost-effectiveness, and appropriate use of SPECT myocardial perfusion imaging (SMPI) versus stress echocardiography in the preoperative evaluation of patients for kidney transplantation.

METHODS

A single-institution, retrospective study was performed. SMPI was performed with regadenoson and stress echocardiography predominantly with dobutamine. Findings on subsequent coronary angiography were correlated. A cost analysis for SMPI versus stress echocardiography was modeled using reimbursements from the Center for Medicare Services.

RESULTS

One hundred thirteen patients underwent imaging (53 SMPI and 60 stress echocardiography). One hundred percent of SMPI studies were diagnostic, compared with only 80% (48/60) in the stress echocardiography group, and this result was statistically significant (χ(2) = 7.96, P < 0.01). The most common reason for a nondiagnostic test was not reaching the target heart rate. In the SMPI group, 15% (8/53) of patients had ischemia on imaging and all underwent subsequent coronary angiography, which confirmed obstructive coronary lesions. One patient with a negative SMPI result underwent a subsequent angiogram that was negative. In the stress echocardiography group, 5% (3/60) of patients had ischemia on imaging and 2 underwent subsequent angiography, which was negative. Three of 12 patients with nondiagnostic examinations underwent further testing. One patient underwent a follow-up positive SMPI scan but no subsequent coronary angiography. The other 2 patients underwent coronary angiography, which was negative. Of the 45 negative stress echocardiography patients, 6 (13%) underwent angiography, with a positive result for obstructive coronary artery disease in 3 of 6. For the modeling of cost analysis, rates of $1,173 and $1,521 (Center for Medicare Services) were used for SMPI and stress echocardiography, respectively. The model assumed that all nondiagnostic imaging would be referred for further stress testing (i.e., nondiagnostic stress echocardiography would be referred for SMPI). This model estimated that initial noninvasive testing with stress echocardiography versus SMPI resulted in a 50% greater cost.

CONCLUSION

For the preoperative evaluation of kidney transplantation, SMPI is more often diagnostic than stress echocardiography. A cost model estimates that initial noninvasive diagnostic testing with stress echocardiography would result in an approximately 50% greater cost than SMPI. Our data also suggest that SMPI has greater diagnostic accuracy than stress echocardiography. Therefore, this single-institution experience supports SMPI as the more appropriate test.

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.

Extensive preoperative testing is not necessary in morbidly obese patients undergoing gastric bypass

Morbidly obese patients are considered at high risk for perioperative complications and often undergo extensive testing for preoperative clearance. We analyzed prospectively collected data from 193 patients undergoing weight loss surgery between November 2000 and November 2002. Preoperative chest x-ray examination, pulmonary function tests, noninvasive cardiac testing, and blood work were performed routinely. Preoperative testing identified abnormalities on eight chest x-ray films (4%) and 29 electrocardiograms (15%), none of which required preoperative intervention. Spirometry was abnormal in 41 patients (21%); logistic regression identified preexisting asthma as predictive of obstructive physiology (odds ratio [OR] 3.3; 95% confidence interval [CI] 1.2 to 8.9), and body mass index as predictive of restrictive physiology (OR 1.1; 95% CI 1.01 to 1.2). Arterial blood gases identified only one case of severe hypoxemia requiring intervention. Mild hypoxemia was associated with increasing age (OR 14.5; 95% CI 1.8 to 114). Echocardiography demonstrated four abnormalities (2%); previous history of cardiac disease was the only risk factor (OR 14.5; 95% CI 1.8 to 114). Complete blood count did not identify 84% and 50% of the patients with iron (n=31) and vitamin B(12) (n=12) deficiencies, respectively. Age, body mass index, and history of asthma were associated with abnormal pulmonary function tests and previous cardiac disease with abnormal cardiac testing. These tests are not mandatory as a routine preoperative evaluation and can be used selectively on the basis of medical history.