Correlation between clinical outcomes and appropriateness grading for referral to myocardial perfusion imaging for preoperative evaluation prior to non-cardiac surgery

The comparative and added prognostic value of biomarkers to the Revised Cardiac Risk Index for preoperative prediction of major adverse cardiac events and all-cause mortality in patients who undergo noncardiac surgery

BACKGROUND

The Revised Cardiac Risk Index (RCRI) is a widely acknowledged prognostic model to estimate preoperatively the probability of developing in-hospital major adverse cardiac events (MACE) in patients undergoing noncardiac surgery. However, the RCRI does not always make accurate predictions, so various studies have investigated whether biomarkers added to or compared with the RCRI could improve this.

OBJECTIVES

Primary: To investigate the added predictive value of biomarkers to the RCRI to preoperatively predict in-hospital MACE and other adverse outcomes in patients undergoing noncardiac surgery. Secondary: To investigate the prognostic value of biomarkers compared to the RCRI to preoperatively predict in-hospital MACE and other adverse outcomes in patients undergoing noncardiac surgery. Tertiary: To investigate the prognostic value of other prediction models compared to the RCRI to preoperatively predict in-hospital MACE and other adverse outcomes in patients undergoing noncardiac surgery.

SEARCH METHODS

We searched MEDLINE and Embase from 1 January 1999 (the year that the RCRI was published) until 25 June 2020. We also searched ISI Web of Science and SCOPUS for articles referring to the original RCRI development study in that period.

SELECTION CRITERIA

We included studies among adults who underwent noncardiac surgery, reporting on (external) validation of the RCRI and: - the addition of biomarker(s) to the RCRI; or - the comparison of the predictive accuracy of biomarker(s) to the RCRI; or - the comparison of the predictive accuracy of the RCRI to other models. Besides MACE, all other adverse outcomes were considered for inclusion.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form based on the CHARMS checklist. Independent pairs of authors screened references, extracted data and assessed risk of bias and concerns regarding applicability according to PROBAST. For biomarkers and prediction models that were added or compared to the RCRI in ≥ 3 different articles, we described study characteristics and findings in further detail. We did not apply GRADE as no guidance is available for prognostic model reviews.

MAIN RESULTS

We screened 3960 records and included 107 articles.   Over all objectives we rated risk of bias as high in ≥ 1 domain in 90% of included studies, particularly in the analysis domain. Statistical pooling or meta-analysis of reported results was impossible due to heterogeneity in various aspects: outcomes used, scale by which the biomarker was added/compared to the RCRI, prediction horizons and studied populations.  Added predictive value of biomarkers to the RCRI Fifty-one studies reported on the added value of biomarkers to the RCRI. Sixty-nine different predictors were identified derived from blood (29%), imaging (33%) or other sources (38%). Addition of NT-proBNP, troponin or their combination improved the RCRI for predicting MACE (median delta c-statistics: 0.08, 0.14 and 0.12 for NT-proBNP, troponin and their combination, respectively). The median total net reclassification index (NRI) was 0.16 and 0.74 after addition of troponin and NT-proBNP to the RCRI, respectively. Calibration was not reported. To predict myocardial infarction, the median delta c-statistic when NT-proBNP was added to the RCRI was 0.09, and 0.06 for prediction of all-cause mortality and MACE combined. For BNP and copeptin, data were not sufficient to provide results on their added predictive performance, for any of the outcomes. Comparison of the predictive value of biomarkers to the RCRI  Fifty-one studies assessed the predictive performance of biomarkers alone compared to the RCRI. We identified 60 unique predictors derived from blood (38%), imaging (30%) or other sources, such as the American Society of Anesthesiologists (ASA) classification (32%). Predictions were similar between the ASA classification and the RCRI for all studied outcomes. In studies different from those identified in objective 1, the median delta c-statistic was 0.15 and 0.12 in favour of  BNP and NT-proBNP alone, respectively, when compared to the RCRI, for the prediction of MACE. For C-reactive protein, the predictive performance was similar to the RCRI. For other biomarkers and outcomes, data were insufficient to provide summary results. One study reported on calibration and none on reclassification. Comparison of the predictive value of other prognostic models to the RCRI   Fifty-two articles compared the predictive ability of the RCRI to other prognostic models. Of these, 42% developed a new prediction model, 22% updated the RCRI, or another prediction model, and 37% validated an existing prediction model. None of the other prediction models showed better performance in predicting MACE than the RCRI. To predict myocardial infarction and cardiac arrest, ACS-NSQIP-MICA had a higher median delta c-statistic of 0.11 compared to the RCRI. To predict all-cause mortality, the median delta c-statistic was 0.15 higher in favour of ACS-NSQIP-SRS compared to the RCRI. Predictive performance was not better for CHADS₂, CHA₂DS₂-VASc, R₂CHADS₂, Goldman index, Detsky index or VSG-CRI compared to the RCRI for any of the outcomes. Calibration and reclassification were reported in only one and three studies, respectively.

AUTHORS' CONCLUSIONS

Studies included in this review suggest that the predictive performance of the RCRI in predicting MACE is improved when NT-proBNP, troponin or their combination are added. Other studies indicate that BNP and NT-proBNP, when used in isolation, may even have a higher discriminative performance than the RCRI. There was insufficient evidence of a difference between the predictive accuracy of the RCRI and other prediction models in predicting MACE. However, ACS-NSQIP-MICA and ACS-NSQIP-SRS outperformed the RCRI in predicting myocardial infarction and cardiac arrest combined, and all-cause mortality, respectively. Nevertheless, the results cannot be interpreted as conclusive due to high risks of bias in a majority of papers, and pooling was impossible due to heterogeneity in outcomes, prediction horizons, biomarkers and studied populations. Future research on the added prognostic value of biomarkers to existing prediction models should focus on biomarkers with good predictive accuracy in other settings (e.g. diagnosis of myocardial infarction) and identification of biomarkers from omics data. They should be compared to novel biomarkers with so far insufficient evidence compared to established ones, including NT-proBNP or troponins. Adherence to recent guidance for prediction model studies (e.g. TRIPOD; PROBAST) and use of standardised outcome definitions in primary studies is highly recommended to facilitate systematic review and meta-analyses in the future.

Association between abnormal myocardial scintigraphy findings and long-term outcomes for elderly patients 85 years or older: a retrospective cohort study

Background

Normal findings of cardiac scintigraphy predict good outcomes. However, a paucity of the data exists for elderly patients 85 years or older. In the present study, we aimed to demonstrate the association between the abnormal findings of cardiac scintigraphy and the risk of all cause death in patients 85 years or older.

Methods

We enrolled 143 consecutive patients 85 years or older with known or suspected coronary artery disease who underwent stress scintigraphy under adenosine or an exercise test and a ^99mTechnetium (Tc)-labeled tracer or thallium 201 (²⁰¹Tl), dual tracer rest scintigraphy using ²⁰¹Tl and ¹²³I-β-methyl iodophenyl pentadecanoic acid (¹²³I-BMIPP), or ¹²³I-BMIPP single tracer scintigraphy. Ischemia was defined by an induced perfusion abnormality according to a provocation test with recovery at rest or decreased uptake of ¹²³I-BMIPP despite normal perfusion at rest. Infarction was defined by perfusion abnormalities assessed by images at rest on ²⁰¹Tl or ^99mTc-labeled tracer. We defined these findings as abnormal when at least one of these aforementioned characteristics was observed.

Results

Patients in the abnormal findings group (N = 62) were more likely to have undergone prior coronary angiography and to have decreased ejection fraction than those in the normal findings group (N = 81). The median follow-up duration was 797 days (interquartile range, 635–1045 days), with follow-up rates of 90% at 1 year and 73% at 2 years. The 2-year mortality rate were significantly higher in the abnormal findings group than in the normal findings group (26.8% vs. 10.9%; p = 0.01). The risk of abnormal findings relative to normal findings remained significant for the mortality (adjusted hazard ratio, 5.99; 95% CI, 1.37–42.8; P = 0.015).

Conclusion

Abnormal myocardial scintigraphy findings were associated with the increased risk for mortality, even for patients 85 years or older.

Pre-operative stress testing in the evaluation of patients undergoing non-cardiac surgery: A systematic review and meta-analysis

Background

Pre-operative stress testing is widely used to evaluate patients for non-cardiac surgeries. However, its value in predicting peri-operative mortality is uncertain. The objective of this study is to assess the type and quality of available evidence in a comprehensive and statistically rigorous evaluation regarding the effectiveness of pre-operative stress testing in reducing 30-day post -operative mortality following non -cardiac surgery.

Methods

The databases of MEDLINE, EMBASE, and CENTRAL databases (from inception to January 27, 2016) were searched for all studies in English. We included studies with pre-operative stress testing prior to 10 different non-cardiac surgery among adults and excluded studies with sample size<15. The data on study characteristics, methodology and outcomes were extracted independently by two observers and checked by two other observers. The primary outcome was 30-day mortality. We performed random effects meta-analysis to estimate relative risk (RR) and 95% confidence intervals (95% CI) in two-group comparison and pooled the rates for stress test alone. Heterogeneity was assessed using I² and methodological quality of studies using Newcastle-Ottawa Quality Assessment Scale. The predefined protocol was registered in PROSPERO #CRD42016049212.

Results

From 1807 abstracts, 79 studies were eligible (297,534 patients): 40 had information on 30-day mortality, of which 6 studies compared stress test versus no stress test. The risk of 30-day mortality was not significant in the comparison of stress testing versus none (RR: 0.79, 95% CI = 0.35–1.80) along with weak evidence for heterogeneity. For the studies that evaluated stress testing without a comparison group, the pooled rates are 1.98% (95% CI = 1.25–2.85) with a high heterogeneity. There was evidence of potential publication bias and small study effects.

Conclusions

Despite substantial interest and research over the past 40 years to predict 30-day mortality risk among patients undergoing non-cardiac surgery, the current body of evidence is insufficient to derive a definitive conclusion as to whether stress testing leads to reduced peri-operative mortality.

Prevalence and predictors of myocardial ischemia by preoperative myocardial perfusion single photon emission computed tomography in patients undergoing noncardiac surgery

BACKGROUND

The prevalence and predictors of myocardial ischemia before noncardiac surgery are unknown. In addition the predictive value of myocardial perfusion single-photon emission computed tomography (SPECT) before noncardiac in individual patients is uncertain.

OBJECTIVE

Evaluate the prevalence and predictors of myocardial ischemia before noncardiac surgery, and determine the postoperative cardiac outcome based on results of myocardial perfusion SPECT.

DESIGN

Retrospective.

SETTING

Single tertiary care center.

PATIENTS AND METHODS

We reviewed the records of adult patients diagnosed with myocardial ischemia by myocardial perfusion SPECT who were undergoing noncardiac surgery. Myocardial perfusion SPECT had been performed within 4 weeks prior to noncardiac surgery requiring general anesthesia.

MAIN OUTCOME MEASURES

Prevalence of abnormal myocardial perfusion SPECT results on preoperative evaluation; abnormal myocardial perfusion SPECT results as a predictor for postoperative cardiac events such as cardiac death, nonfatal myocardial infarction, and unstable angina.

RESULTS

Of 131 patients who underwent noncardiac surgery from February 2015 to April 2016, 84 (64%) patients were female and the mean (SD) age was 64.1 (13.6) years. The prevalence of abnormal myocardial perfusion SPECT was 18% (24 of 131). Normal myocardial perfusion SPECT was highly predictive (up to 100%), but a positive myocardial perfusion SPECT had low positive predictive value (4%). Variables associated with an abnormal myocardial perfusion SPECT included ischemic heart disease, congestive heart failure, ASA score of 3 or more, limited exercise capacity (less than 4 METs), male sex, hypercholesterolemia, hypertension, smoking, and abnormal ECG. In a multivariable analysis, history of ischemic heart disease and history of smoking were significant predictors of abnormal myocardial perfusion SPECT (P=.001, and .029, respectively).

CONCLUSIONS

Because of the low positive predictive value of myocardial perfusion SPECT, utilization of the technique in the workup of cardiac patients undergoing noncardiac surgery has been inappropriate. Myocardial perfusion SPECT should be restricted to only clearly defined appropriate use criteria.

LIMITATIONS

Relatively small number of patients and retrospective design.

Long-Term Prognostic Value of Appropriate Myocardial Perfusion Imaging

Appropriate use criteria (AUC) for single-photon emission computed tomography myocardial perfusion images (SPECT-MPIs) were developed to address the growth of cardiac imaging studies. Long-term prognostic value of AUC in SPECT-MPI has not been tested in existing cohorts. We sought to determine the long-term prognostic value of MPI classified as appropriate. AUC was evaluated in a prospectively designed cohort of patients who underwent clinically indicated MPI. MPI studies were classified based on 2009 AUC for SPECT-MPI. Data regarding downstream coronary angiography (cath), revascularization and all-cause mortality, cardiac death, and nonfatal myocardial infarction (MI) were collected from national registries. Among n = 1,129 MPI scans that received an appropriate grading, 148 all-cause deaths, 109 MIs, 58 cardiac deaths, 152 caths, 113 revascularization procedures occurred over a mean follow-up period of 5.4 ± 1.2 years (0.9% cardiac death rate per year, 1.8% MI rate per year). Most of the scans were low-risk normal MPI scans (summed stress score ≤3; 74.1%). An abnormal scan was associated with higher rates of MI (19.5% vs 6.2%, hazard ratio 1.72, p = 0.017) and cardiac death (13.4% vs 2.3%, hazard ratio 2.12, p = 0.016). In conclusion, MPI scans classified as appropriate have long-term prognostic value, despite a high proportion of low-risk scans. This provides support for clinicians to consider the use of appropriate grading in addition to MPI scan results in patient management.

Outcomes after inappropriate nuclear myocardial perfusion imaging: A meta-analysis

BACKGROUND

The relationship between inappropriate MPI and cardiovascular outcomes is poorly understood. We sought to systematically review the literature on appropriate use criteria (AUC) for MPI, including temporal trend of inappropriate testing and resulting cardiovascular outcomes.

METHODS

We searched the MEDLINE database for studies related to AUC and MPI. The co-primary outcomes were abnormal test results and the presence of cardiac ischemia. Random effects odds ratios (OR) were constructed using DerSimonian-Laird method.

RESULTS

A total of 22 studies with 23,443 patients were included. The prevalence of inappropriate testing was 14.8% [95% confidence interval (CI) 11.6%-18.7%]. Inappropriate MPI studies were less likely to be abnormal (OR 0.41 95% CI 0.35-0.49, P < .0001) and to demonstrate ischemia (OR 0.40, 95% CI 0.24-0.67, P < .0001) compared to appropriate testing. No difference in the rate of inappropriate tests was detected based on the midpoint of the enrollment year (P = .54). The pattern of ordering inappropriate studies was not different between cardiology and non-cardiology providers (OR 0.74, 95% CI 0.51-1.06, P = .10).

CONCLUSION

Inappropriate MPI studies are less likely to yield abnormal results or demonstrate myocardial ischemia. The rate of inappropriate MPI has not decreased over time.

Practice-Level Variation in Outpatient Cardiac Care and Association With Outcomes

BACKGROUND

Utilization of cardiac services varies across regions and hospitals, yet little is known regarding variation in the intensity of outpatient cardiac care across cardiology physician practices or the association with clinical endpoints, an area of potential importance to promote efficient care.

METHODS AND RESULTS

We included 7 160 732 Medicare beneficiaries who received services from 5635 cardiology practices in 2012. Beneficiaries were assigned to practices providing the plurality of office visits, and practices were ranked and assigned to quartiles using the ratio of observed to predicted annual payments per beneficiary for common cardiac services (outpatient intensity index). The median (interquartile range) outpatient intensity index was 1.00 (0.81-1.24). Mean payments for beneficiaries attributed to practices in the highest (Q4) and lowest (Q1) quartile of outpatient intensity were: all cardiac payments (Q4 $1272 vs Q1 $581; ratio, 2.2); cardiac catheterization (Q4 $215 vs Q1 $64; ratio, 3.4); myocardial perfusion imaging (Q4 $253 vs Q1 $83; ratio, 3.0); and electrophysiology device procedures (Q4 $353 vs Q1 $142; ratio, 2.5). The adjusted odds ratios (95% CI) for 1 incremental quartile of outpatient intensity for each outcome was: cardiac surgical/procedural hospitalization (1.09 [1.09, 1.10]); cardiac medical hospitalization (1.00 [0.99, 1.00]); noncardiac hospitalization (0.99 [0.99, 0.99]); and death at 1 year (1.00 [0.99, 1.00]).

CONCLUSION

Substantial variation in the intensity of outpatient care exists at the cardiology practice level, and higher intensity is not associated with reduced mortality or hospitalizations. Outpatient cardiac care is a potentially important target for efforts to improve efficiency in the Medicare population.

Effective risk stratification of patients on the basis of myocardial perfusion SPECT is dependent on appropriate patient selection

Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is commonly used in risk assessment, as an abnormal scan predicts a multifold increase in cardiac risk. Recent studies have showed that application of the appropriate use criteria (AUC) sharpens the prognostic value of SPECT-MPI, while inappropriate use is clinically ineffective and may lead to unnecessary downstream invasive testing and revascularization procedures. In this review, we will discuss recent literature examining the impact of appropriate use on the prognostic value of SPECT-MPI and downstream decision-making. We will also discuss the implications of appropriate use on cost-effectiveness of MPI.

Temporal changes in appropriateness of cardiac imaging

BACKGROUND

Appropriate use criteria (AUC) for cardiac imaging have been available for almost 10 years. The extent to which there has been a reported improvement in appropriate use is undefined.

OBJECTIVES

This study systematically reviewed published evidence to identify whether the promulgation of AUC has led to an improvement in the proportion of appropriate cardiac imaging requests.

METHODS

Electronic databases were systematically searched for English-language papers related to AUC and cardiovascular imaging. We found 59 reports involving 103,567 tests that were published from 2000 to 2012. The rate of appropriate testing over time was analyzed in a meta-regression.

RESULTS

New AUC were associated with apparent improvements in appropriateness for transthoracic echocardiography (TTE) (80% [95% confidence interval (CI): 0.75 to 0.84] vs. 85% [95% CI: 0.81 to 0.89]), transesophageal echocardiography (TEE) (89% [95% CI: 0.81 to 0.94] vs. 95% [95% CI: 0.93 to 0.96]) and computed tomography angiography (CTA) (37% [95% CI: 0.21 to 0.55] vs. 55% [95% CI: 0.44 to 0.65]) but not stress echocardiography (53% [95% CI: 0.45 to 0.61] vs. 52% [95% CI: 0.42 to 0.61]) or single-photon emission computed tomography (72% [95% CI: 0.66 to 0.77] vs. 68% [95% CI: 0.60 to 0.74]). Although there were no correlations between the proportion of appropriate TTEs and published year (p = 0.36) for 2007 AUC, there was a positive correlation between proportion of appropriateness and the year of publication (p = 0.01) for 2011 AUC. There was a significant decrease in the proportion of appropriateness over time using the 2007 TEE AUC (p = 0.03) and 2006 CT AUC (p = 0.02). There were no meaningful associations between appropriateness and publication year for stress echocardiography, CTA, or single-photon emission computed tomography.

CONCLUSIONS

Rates of reported appropriate use in imaging show improvements for TTE and CTA but not for stress imaging and TEE. The observed reductions in imaging studies are not matched by reported rates of appropriate use.

Clinical utility of inappropriate positron emission tomography myocardial perfusion imaging: test results and cardiovascular events

BACKGROUND

Appropriate use criteria for myocardial perfusion imaging (MPI) were developed to categorize scenarios where MPI might be beneficial (appropriate) or not (inappropriate). Few investigations have evaluated the clinical utility of this categorization strategy, particularly with positron emission tomography (PET) MPI.

METHODS AND RESULTS

We conducted this retrospective cohort investigation in a Veterans Affairs (VA) medical center, on predominantly male subjects who underwent PET-MPI. We correlated appropriateness to test result and cardiovascular events. Of 521 subjects, 414 (79.5%) were appropriate, 54 (10.4%) were uncertain, and 53 (10.2%) were inappropriate. PET-MPI was abnormal more often when appropriate or uncertain (28% and 34.6%, respectively, vs 7.7% for inappropriate, P = .003). Among abnormal inappropriate tests, none detected occult ischemia. By Cox regression, summed difference score ≥5 (HR 5.06, 95% CI 2.72-9.44) and an abnormal test result (HR 4.48, 95% CI 2.19-9.14) were associated with higher likelihood of catheterization. Log-rank analysis demonstrated similar likelihood of catheterization when comparing abnormal vs normal test result (P < .0001) and between appropriate, uncertain, and inappropriate tests (P = .024).

CONCLUSIONS

Inappropriate PET-MPI was rarely abnormal, associated with low catheterization rates, and failed to detect occult ischemia for any subjects. The clinical utility of inappropriate PET-MPI is negligible.

Update on cardiac imaging techniques 2012

Cardiac imaging is one of the basic pillars of modern cardiology. The potential list of scenarios where cardiac imaging techniques can provide relevant information is simply endless so it is impossible to include all relevant new features of cardiac imaging published in the literature in 2012 in the limited format of a single article. We summarize the year's most relevant news on cardiac imaging, highlighting the ongoing development of myocardial deformation and 3-dimensional echocardiography techniques and the increasing use of magnetic resonance imaging and computed tomography in daily clinical practice.

Utilization patterns of single-photon emission cardiac tomography myocardial perfusion imaging studies in a rural tertiary care setting

BACKGROUND

Appropriate use criteria (AUC) for single-photon emission computed tomographic myocardial perfusion imaging (SPECT MPI) were revised in 2009 to include 15 new clinical scenarios. We assessed multivariable predictors and overall appropriateness of MPI studies performed in a rural tertiary care setting.

HYPOTHESIS

We hypothesized that appropriate utilization rates of SPECT MPI imaging in a rural tertiary care center are similar for cardiology and non cardiology providers.

METHODS

We reviewed all SPECT MPI studies performed for over a 6-month period at our center. Using 67 scenarios in AUC, we categorized these studies as appropriate, inappropriate, uncertain, or unclassifiable.

RESULTS

Of 328 MPI studies, 287 (88%) studies were classified as appropriate, 18 (5.5%) as inappropriate, 23 (7%) as uncertain, and none as unclassifiable. Preoperative testing accounted for 44% of the inappropriate studies; 61% of uncertain tests were ordered for cardiovascular risk assessment in patients with prior normal coronary angiography or normal stress tests. The ordering provider specialty did not show any relation with appropriateness of the test (P = 0.46). Patients with inappropriate and uncertain studies were younger than patients with appropriate studies (P = 0.007).

CONCLUSIONS

We found that a majority of MPI studies are performed for appropriate indications regardless of ordering provider specialty. Few common scenarios accounted for the majority of the inappropriate or uncertain studies.