Determinants of variations in coronary revascularization practices

Predictors of Initial Revascularization Versus Medical Therapy Alone in Patients With Non–ST-Segment–Elevation Acute Coronary Syndrome Undergoing an Invasive Strategy

Background—

Although an invasive strategy is a class I clinical practice guideline for non–ST-segment–elevation acute coronary syndromes, there is wide variation in the proportion of patients who undergo revascularization despite early angiography. We sought to identify the predictors of early revascularization versus medical therapy alone in patients with non–ST-segment–elevation acute coronary syndrome undergoing an invasive strategy and to assess their clinical outcomes.

Methods and Results—

We assessed revascularization status by percutaneous coronary intervention or coronary artery bypass grafting within 7 days of the index angiogram in all patients with non–ST-segment–elevation acute coronary syndrome who underwent an invasive strategy in Ontario, Canada, from October 1, 2008, to October 31, 2013, with follow-up through December 31, 2014. The primary outcome was mortality. Multivariable hierarchical logistic models identified predictors of revascularization, and multivariable Cox models with treatment strategy as a 3-level time-varying covariate assessed the relationship between revascularization status and clinical outcomes. We identified 50 302 patients of whom 34 288 (68.2%) underwent revascularization (percutaneous coronary intervention: 28 011 and coronary artery bypass grafting: 6277). There was a 2-fold variation in revascularization rates across hospitals. A higher risk presentation significantly predicted revascularization (odds ratio, 1.26; 95% confidence interval, 1.18–1.35), as did having the angiogram by an interventional cardiologist (odds ratio, 1.76; 95% confidence interval, 1.57–1.98). Revascularized patients with either percutaneous coronary intervention (hazard ratio, 0.64; 95% confidence interval, 0.60–0.69) or coronary artery bypass grafting (hazard ratio, 0.53; 95% confidence interval, 0.47–0.60) had improved survival compared with medically treated patients.

Conclusions—

Although the majority of patients with non–ST-segment–elevation acute coronary syndrome who underwent an early invasive approach received revascularization, there was wide variation. Revascularization was associated with significantly improved survival.

Association between publication of appropriate use criteria and the temporal trends in diagnostic angiography in stable coronary artery disease: A population-based study

BACKGROUND

The appropriate use criteria (AUC) were developed to aid clinicians in making clinical decisions regarding coronary angiography. The aim of the present study was to evaluate the association between the publication of the AUC criteria in diagnostic angiography and rates of angiography in Ontario.

METHODS

Our cohort consisted of all patients who underwent coronary angiography in Ontario from 1st October 2008 to 31st October 2013 for the indication of suspected stable coronary artery disease. We determined monthly age- and sex-standardized rates of angiography per 100,000 adults. To determine the association between the publication of the AUC for diagnostic angiograms and the rates of angiography, we conducted a time series analysis using an autoregressive integrated moving average model. As a sensitivity analyses, we evaluated the impact of the AUC on the rates of percutaneous coronary intervention (PCI) per 100 angiograms.

RESULTS

We included 114,551 angiograms for stable coronary artery disease. In the period prior to the publication of the AUC, the average monthly age- and sex-standardized rate of angiography was 18.7 per 100,000; post-AUC, the average monthly rate decreased to 17.6 per 100,000 adults (P = .037). In contrast, in the 29,358 PCIs included in the analysis, the monthly PCI rates per 100 angiograms were unchanged (25.2 pre-AUC; 26.8 post-AUC; P = .29). In the sensitivity analysis, the rate of appropriate/inappropriate and uncertain indication did not significantly change over the study period.

CONCLUSIONS

The publication of the diagnostic angiography AUC criteria was associated with a decrease in the population rates of diagnostic angiography. This suggests that the AUC potentially was associated with an increased threshold to pursue invasive diagnostic testing.

Revascularization in stable coronary artery disease: a combined perspective from an interventional cardiologist and a cardiac surgeon

It is now half a century since the start of coronary bypass graft surgery (CABG) with the first percutaneous coronary intervention (PCI) following just over a decade later. The relative merits of PCI vs. CABG for stable coronary artery disease (stable-CAD) have continued to be debated ever since and have been the focus of around 20 randomized trials and numerous registry studies, systematic reviews, and meta-analyses. The aim of this review is to identify areas of agreement, disagreement, and uncertainties in the role of PCI and CABG in patients with stable-CAD.

Treatment variation in stent choice in patients with stable or unstable coronary artery disease

AIM

Variations in treatment are the result of differences in demographic and clinical factors (e.g. anatomy), but physician and hospital factors may also contribute to treatment variation. The choice of treatment is considered important since it could lead to differences in long-term outcomes. This study explores the associations with stent choice: i.e. drug-eluting stent (DES) versus bare-metal stents (BMS) for Dutch patients diagnosed with stable or unstable coronary artery disease (CAD).

METHODS & RESULTS

Associations with treatment decisions were based on a prospective cohort of 692 patients with stable or unstable CAD. Of those patients, 442 patients were treated with BMS or DES. Multiple logistic regression analyses were performed to identify variables associated with stent choice. Bivariate analyses showed that NYHA class, number of diseased vessels, previous percutaneous coronary intervention, smoking, diabetes, and the treating hospital were associated with stent type. After correcting for other associations the treating hospital remained significantly associated with stent type in the stable CAD population.

CONCLUSIONS

This study showed that several factors were associated with stent choice. While patients generally appear to receive the most optimal stent given their clinical characteristics, stent choice seems partially determined by the treating hospital, which may lead to differences in long-term outcomes.

Predictors and Outcomes of Routine Versus Optimal Medical Therapy in Stable Coronary Heart Disease

Although randomized studies have shown optimal medical therapy (OMT) to be as efficacious as revascularization in stable coronary heart disease (CHD), the application of OMT in routine practice is suboptimal. We sought to understand the predictors of receiving OMT in stable CHD and its impact on clinical outcomes. All patients with stable CHD based on coronary angiography from October 2008 to September 2011 were identified in Ontario, Canada. OMT was defined as concurrent use of β blocker, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, and statin. Aspirin use was not part of the OMT definition because of database limitations. Multivariable hierarchical logistic models identified predictors of OMT in the 12 months after angiography. Cox proportional hazard models with time-varying covariates for OMT and revascularization status examined differences in death and nonfatal myocardial infarction (MI). In these models, patients transitioned among 4 mutually exclusive treatment groups: no OMT and no revascularization, no OMT and revascularization, OMT and no revascularization, OMT and revascularization. Our cohort had 20,663 patients. Over a mean period of 2.5 years, 8.7% had died. Only 61% received OMT within 12 months. The strongest predictor of receiving OMT at 12 months was OMT before the angiogram (odds ratio 14.40, 95% confidence interval [CI] 13.17 to 15.75, p <0.001). Relative to no OMT and nonrevascularized patients, patients on OMT and revascularized had the greatest reduction in mortality (hazard ratio 0.52, 95% CI 0.45 to 0.60, p <0.001) and nonfatal MI (hazard ratio 0.74, 95% CI 0.64 to 0.84, p <0.001). In conclusion, our study highlights the low rate of OMT in stable CHD. Patients who received both OMT and revascularization achieved the greatest reduction in mortality and nonfatal MI.

Determinants of variations in initial treatment strategies for stable ischemic heart disease

BACKGROUND

The ratio of revascularization to medical therapy (referred to herein as the revascularization ratio) for the initial treatment of stable ischemic heart disease varies considerably across hospitals. We conducted a comprehensive study to identify patient, physician and hospital factors associated with variations in the revascularization ratio across 18 cardiac centres in the province of Ontario. We also explored whether clinical outcomes differed between hospitals with high, medium and low ratios.

METHODS

We identified all patients in Ontario who had stable ischemic heart disease documented by index angiography performed between Oct. 1, 2008, and Sept. 30, 2011, at any of the 18 cardiac centres in the province. We classified patients by initial treatment strategy (medical therapy or revascularization). Hospitals were classified into equal tertiles based on their revascularization ratio. The primary outcome was all-cause mortality. Patient follow-up was until Dec. 31, 2012. Hierarchical logistic regression models identified predictors of revascularization. Multivariable Cox proportional hazards models, with a time-varying covariate for actual treatment received, were used to evaluate the impact of the revascularization ratio on clinical outcomes.

RESULTS

Variation in revascularization ratios was twofold across the hospitals. Patient factors accounted for 67.4% of the variation in revascularization ratios. Physician and hospital factors were not significantly associated with the variation. Significant patient-level predictors of revascularization were history of smoking, multivessel disease, high-risk findings on noninvasive stress testing and more severe symptoms of angina (v. no symptoms). Treatment at hospitals with a high revascularization ratio was associated with increased mortality compared with treatment at hospitals with a low ratio (hazard ratio 1.12, 95% confidence interval 1.03-1.21).

INTERPRETATION

Most of the variation in revascularization ratios across hospitals was warranted, in that it was driven by patient factors. Nonetheless, the variation was associated with potentially important differences in mortality.

Validation of the appropriate use criteria for coronary angiography: a cohort study

BACKGROUND

The use of invasive coronary angiography in stable ischemic heart disease (IHD) varies widely.

OBJECTIVE

To validate the 2012 appropriate use criteria for diagnostic catheterization by examining the relationship between the appropriateness of cardiac catheterization in patients with suspected stable IHD and the proportion of patients with obstructive coronary artery disease (CAD) and subsequent revascularization.

DESIGN

Population-based, observational, multicenter cohort study.

SETTING

The Cardiac Care Network, a registry of all patients having elective angiography at 18 hospitals in Ontario, Canada, between 1 October 2008 and 30 September 2011.

PATIENTS

Persons without prior coronary revascularization or myocardial infarction who had angiography for suspected stable CAD.

MEASUREMENTS

Appropriateness scores were ascertained by using data collected at the time of the index angiography and were categorized as appropriate, inappropriate, or uncertain.

RESULTS

Among the final cohort of 48 336 patients, 58.2% of angiographic studies were classified as appropriate, 10.8% were classified as inappropriate, and 31.0% were classified as uncertain. Overall, 45.5% of patients had obstructive CAD. In patients with appropriate indications for angiography, 52.9% had obstructive CAD, with 40.0% undergoing revascularization. In those with inappropriate indications, 30.9% had obstructive CAD and 18.9% underwent revascularization; in those with uncertain indications, 36.7% had obstructive CAD and 25.9% had revascularization. Although more patients with appropriate indications had obstructive CAD and underwent revascularization (P < 0.001), a substantial proportion of those with inappropriate or uncertain indications had important coronary disease.

LIMITATION

Data were not available on whether symptoms were atypical.

CONCLUSION

Despite the association between appropriateness category and obstructive CAD, this study raises concerns about the ability of the appropriate use criteria to guide clinical decision making.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research.

Impact of system and physician factors on the detection of obstructive coronary disease with diagnostic angiography in stable ischemic heart disease

BACKGROUND

Wide variation exists in the detection rate of obstructive coronary artery disease (CAD) with elective coronary angiography for suspected stable ischemic heart disease. We sought to understand the incremental impact of nonclinical factors on this variation.

METHODS AND RESULTS

We included all patients who underwent coronary angiography for possible suspected stable ischemic heart disease, from October 1, 2008, to September 30, 2011, in Ontario, Canada. Nonclinical factors of interest included physician self-referral for angiography, the physician type (invasive or interventional), and hospital type. Hospitals were categorized into diagnostic angiogram only centers, stand-alone percutaneous coronary intervention centers, or full service centers with coronary artery bypass surgery available. Multivariable hierarchical logistic models were developed to identify system and physician-level predictors of obstructive CAD, after adjustment for patient factors. Our cohort consisted of 60 986 patients, of whom 31 726 had obstructive CAD (52.0%), with significant range across hospitals from 37.3% to 69.2%. Fewer self-referral patients (49.8%) had obstructive CAD compared with nonself-referral patients (53.5%), with an odds ratio of 0.89 (95% confidence interval, 0.86-0.93; P<0.001). Angiograms performed by invasive physicians had a lower likelihood of obstructive CAD compared with those by interventional physicians (48.2% versus 56.9%; odds ratio, 0.85; 95% confidence interval, 0.81-0.90; P<0.001). Fewer angiograms at diagnostic only centers showed obstructive CAD (42.0%) compared with full service centers (55.1%; odds ratio, 0.62; 95% confidence interval, 0.39-0.98; P=0.04). Nonclinical factors accounted for 23.8% of the variation between hospitals.

CONCLUSIONS

Physician and system factors are important predictors of obstructive CAD with coronary angiography.

Comparative-effectiveness of revascularization versus routine medical therapy for stable ischemic heart disease: a population-based study

BACKGROUND

Randomized studies have shown optimal medical therapy to be as efficacious as revascularization in stable ischemic heart disease (IHD). It is not known if these efficacy results are reflected by real-world effectiveness.

OBJECTIVE

To evaluate the comparative effectiveness of routine medical therapy versus revascularization with percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) in stable IHD.

DESIGN

Observational cohort study.

PATIENTS

Stable IHD patients from 1 October 2008 to 30 September 2011, identified using a Registry of all angiography patients in Ontario, Canada.

INTERVENTION

Revascularization, defined as PCI/CABG within 90 days after index angiography.

MAIN MEASURES

Death, myocardial infarction (MI) or repeat PCI/CABG. Revascularization was compared to medical therapy using a) multivariable Cox-proportional hazard models with therapy strategy treated as a time-varying covariate; and b) a propensity score matched analysis. Post-angiography medication use was determined.

KEY RESULTS

We identified 39,131 stable IHD patients, of whom 15,139 were treated medically, and 23,992 were revascularized (PCI = 15,604; CABG = 8,388). Mean follow-up was 2.5 years. Revascularization was associated with fewer deaths (HR 0.76; 95 % CI 0.68-0.84; p < 0.001) ,MIs (HR 0.78; 95 % CI 0.72-0.85; p < 0.001) and repeat PCI/CABG (HR 0.59; 95 % CI 0.50-0.70; p < 0.001) than medical therapy. In the propensity-matched analysis of 12,362 well-matched pairs of revascularized and medical therapy patients, fewer deaths (8.6 % vs 12.7 %; HR 0.75; 95 % CI 0.69-0.81; p < 0.001) , MIs (11.7 % vs 14.4 %; HR 0.84; 95 % CI 0.77-0.93 p < 0.001) and repeat PCI/CABG ( 17.4 % vs 24.1 %;HR 0.67; 95 % 0.63-0.71; p < 0.001) occurred in revascularized patients, over the 4.1 years of follow-up. The revascularization patients had higher uptake of clopidogrel (70.3 % vs 27.2 %; p < 0.001), β-blockers (78.2 % vs 76.7 %; p = 0.010), and statins (94.7 % vs 91.5 %, p < 0.001) in the 1-year post-angiogram.

CONCLUSIONS

Stable IHD patients treated with revascularization had improved risk-adjusted outcomes in clinical practice, potentially due to under-treatment of medical therapy patients.

Influence of coronary anatomy and SYNTAX Score on the variations in revascularization strategies for patients with multivessel disease

BACKGROUND

The Variation in Revascularization Practice in Ontario (VRPO) project helped describe variations in revascularization across Ontario. Coronary anatomy was the most important predictor of revascularization strategy. We conducted a novel angiographic substudy of the VRPO cohort to: (1) validate "real-world" coronary angiographic reporting in the province of Ontario; and (2) understand the relationship between variability in revascularization and coronary anatomy complexity.

METHODS

Seventeen hundred eighty-seven angiograms from 17 cardiac centres were randomly sampled from the VRPO cohort. The core lab assessment involved blinded interpretation of each angiographic film. A comparison of agreement in coronary anatomy and treatment strategy between abstracted chart data from the VRPO study and blinded film review was undertaken. Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) scores were calculated for all patients with multivessel disease.

RESULTS

The weighted κ statistic for coronary anatomy was 0.75 (95% confidence interval, 0.72-0.77), suggesting substantial agreement between abstracted chart data and blinded film review. The weighted κ for revascularization strategy was 0.51 (95% confidence interval, 0.47-0.54) suggesting only moderate agreement. There were no significant differences in the mean/median SYNTAX scores across all 4 percutaneous coronary intervention: coronary artery bypass graft (CABG) groups.

CONCLUSIONS

Abstracted chart data in the VRPO project provides a valid assessment of coronary anatomy and furthermore serves as validation of "real-world" coronary angiographic reporting in the province of Ontario. The uniform distribution of coronary complexity across centres in Ontario, with respect to the SYNTAX score, suggests the variation of percutaneous coronary intervention: CABG ratio is not related to a difference in coronary anatomy complexity across sites, but rather a difference in management strategies for the same anatomy.

The changing face of cardiac surgery: practice patterns and outcomes 2001-2010

BACKGROUND

Advances in cardiac surgical care have allowed for successful surgery in high-risk elderly patients. Advances in percutaneous coronary intervention (PCI) techniques and expanded indications for PCI have resulted in a decrease in referrals for coronary artery bypass grafting (CABG). Our objective was to document changes in practice patterns and outcomes in a single tertiary cardiac surgery centre serving a large geographic area.

METHODS

For all cardiac surgery cases performed from 2001-2010 we examined its use, patient clinical characteristics, and outcomes. Frailty was assessed using a measure we have previously demonstrated to be associated with adverse outcomes.

RESULTS

During the study period, annual case volume decreased by 13%. The number of isolated CABG cases declined, and valve surgery and other complex procedures increased. The proportion of patients aged ≥ 80 years rose from 7%-12%, and the proportion of frail patients increased from 4%-10%. Although unadjusted in-hospital mortality remained relatively unchanged, intensive care unit (ICU) stays and prolonged institutional care increased. Older age and frailty were associated with mortality, prolonged ICU stays, prolonged institutional care, and a composite of mortality and major morbidities.

CONCLUSIONS

Our findings showed a decline in CABG, an increase in more complex operations, and an increase in prolonged ICU stays and prolonged institutional care. The proportion of frail and elderly patients increased over time and these patient groups were at higher risk of adverse postoperative outcomes. Particular attention is required in the decision for surgery and perioperative management of these patients.

Predictors of normal coronary arteries at coronary angiography

BACKGROUND

Coronary angiograms are important in the diagnostic workup of patients with suspected coronary artery disease. However, little is known about the clinical predictors of normal angiograms and whether this rate varies across different cardiac centers in Ontario.

METHODS

We conducted a study using the Cardiac Care Network Variations in Revascularization Practice in Ontario database of 2,718 patients undergoing an index cardiac catheterization for an indication of stable angina between April 2006 and March 2007 at one of 17 cardiac hospitals in Ontario. We determined predictors of normal coronary angiograms (0% coronary stenosis) and compared rates of patients with normal catheterizations across centers.

RESULTS

Overall, 41.9% of patients with stable angina had a normal catheterization. A multivariate model demonstrated female gender to be the strongest predictor of a normal angiogram (odds ratio 3.55, 95% CI 2.93-4.28). In addition, atypical ischemic symptoms or no symptoms, the absence of diabetes, hyperlipidemia, smoking history, peripheral vascular disease, and angiography performed at a nonteaching site were associated with higher rates of normal catheterization. The rate of normal angiograms studied varied from 18.4% to 76.9% across hospitals and was more common in community compared with academic settings (47.1% vs 35.4%, P < .001).

CONCLUSIONS

The absence of traditional cardiac risk factors, female gender, and lack of typical angina symptoms are all associated with a higher frequency of normal cardiac catheterizations. The wide variation in Ontario in the frequency of normal angiograms in patients with stable angina suggests that there are opportunities to improve patient case selection.

Assessing the association of appropriateness of coronary revascularization and clinical outcomes for patients with stable coronary artery disease

OBJECTIVES

The study assessed the appropriateness of coronary revascularization in Ontario, Canada, and examined its association with longer-term outcomes.

BACKGROUND

Although appropriate use criteria for coronary revascularization have been developed to improve the rational use of cardiac invasive procedures, it is unknown whether greater adherence to appropriateness guidelines is associated with improved clinical outcomes in stable coronary artery disease.

METHODS

A population-based cohort of stable patients undergoing cardiac catheterization was assembled from April 1, 2006, to March 31, 2007. The appropriateness for coronary revascularization at the time of coronary angiography was retrospectively adjudicated using the appropriate use criteria. Clinical outcomes between coronary revascularization and medical treatment without revascularization, stratified by appropriateness categories, were compared.

RESULTS

In 1,625 patients with stable coronary artery disease, percutaneous coronary intervention or coronary artery bypass grafting was only performed in 69% who had an appropriate indication for coronary revascularization. Coronary revascularization was associated with a lower adjusted hazard of death or acute coronary syndrome (hazard ratio [HR]: 0.61; 95% confidence interval [CI]: 0.42 to 0.88) at 3 years compared with medical therapy in appropriate patients. The rate of coronary revascularization was 54% in the uncertain category and 45% in the inappropriate category. No significant difference in death or acute coronary syndrome between coronary revascularization and no revascularization in the uncertain category (HR: 0.57; 95% CI: 0.28 to 1.16) and the inappropriate category (HR: 0.99; 95% CI: 0.48 to 2.02) was observed.

CONCLUSIONS

Using the appropriateness use criteria, we identified substantial underutilization and overutilization of coronary revascularization in contemporary clinical practice. Underutilization of coronary revascularization is associated with significantly increased risks of adverse outcomes in patients with appropriate indications.