Stress testing after percutaneous coronary interventions: a population-based study

Long-term Clinical Outcomes Following Cardiac Stress Testing After Percutaneous Coronary Intervention

BACKGROUND

Cardiac stress testing (CST) is commonly performed after percutaneous coronary intervention (PCI), yet little is known whether such ischemic testing is associated with improved clinical outcomes.

METHODS

We studied patients who underwent their first PCI procedure from October 2008 to December 2016 in Ontario, Canada. Patients who underwent CST from 60 days to 1 year after PCI were compared with those who did not undergo CST. The primary outcome was a composite of cardiovascular death or hospitalisation for myocardial infarction (MI) at 3 years after CST. Inverse probability of treatment weighting was used to adjust for potential differences between the study groups.

RESULTS

Among the 86,150 included patients, 40,988 (47.6%) underwent CST within 60 days to 1 year after PCI. Patients who underwent CST had higher prescription rates of cardiac medications. At 1 year after CST, rates of cardiac catheterisation and coronary revascularisation were more than double those observed in the nontested group (13.4% vs 5.9%, standardised difference [SD] 0.26, for cardiac catheterisation; 6.6% vs 2.7%, SD 0.19, for PCI). The CST group had a significantly lower primary event rate at 3 years compared without CST (3.9% vs 4.5%, hazard ratio 0.87, 95% confidence interval 0.81-0.93).

CONCLUSIONS

This population-based study of PCI patients found a small but significantly lower risk of cardiovascular events among patients who received CST. Further studies are needed to confirm these findings and determine the specific aspects of care that may be associated with the modestly improved outcomes.

An Association Between Cardiologist Billing Patterns, Health Care Use, and Outcomes in Cardiac Patients

Background

Whether individual cardiologist billings are associated with differences in ambulatory care management and clinical outcomes in patients with coronary artery disease (CAD) and heart failure (HF) remains poorly understood.

Methods

We conducted a population-based, retrospective cohort study of cardiologists who treat patients with CAD or HF using administrative claims data in Ontario, Canada. The primary exposure was cardiologist billing quintile. We then stratified median billing amounts into quintiles, from lowest (quintile 1) to highest billing physicians (quintile 5).

Results

The main outcomes of interest were cardiac diagnostic and therapeutic procedures that occurred within 365 days of the index visit. Our 2 cohorts respectively consisted of 170,959 patients with CAD seen by 1 of 423 cardiologists and 56,262 HF patients seen by 1 of 413 cardiologists. CAD patients of higher-billing cardiologists had higher rates of echocardiograms (adjusted odds ratio [aOR], 1.65; 95% confidence interval [CI], 1.39 to 1.94 for quintile 5 vs quintile 2) and stress tests (aOR, 1.50; 95% CI, 1.28-1.75) at 1 year, with a similar pattern for HF patients of echocardiogram (aOR, 1.40; 95% CI, 1.23-1.59; P < 0.001) and stress test (aOR, 1.32; 95% CI, 1.15-1.51) use. CAD patients of cardiologists in quintile 1 had a higher mortality rate (aOR, 1.16; 95% CI, 1.03-1.31), and HF patients of cardiologists in billing quintile 4 had a lower hospitalization rate at 1 year (OR, 0.94; 95% CI, 0.89-0.99; P = 0.02).

Conclusions

Cardiac patients seen by the highest-billing cardiologists received more noninvasive cardiac testing compared with lower-billing cardiologists.

Low-Density Lipoprotein Cholesterol and Adverse Cardiovascular Events After Percutaneous Coronary Intervention

BACKGROUND

After percutaneous coronary interventions (PCIs), patients remain at high risk of developing late cardiovascular events. Although controlling low-density lipoprotein cholesterol (LDL-C) may improve outcomes after PCI, practice guidelines do not have specific recommendations on LDL-C management for this subgroup.

OBJECTIVES

The purpose of this study was to evaluate LDL-C testing and levels after PCIs, and to assess the association between LDL-C and longer-term cardiovascular events after PCIs.

METHODS

All patients who received their first PCI from October 1, 2011, to September 30, 2014, in Ontario, Canada, were considered for inclusion. Patients who had LDL-C measurement within 6 months after PCI were categorized as: <70 mg/dl, 70 to <100 mg/dl, and ≥100 mg/dl. The primary composite outcome was cardiovascular death, myocardial infarction, coronary revascularization, and stroke through December 31, 2016.

RESULTS

Among 47,884 included patients, 52% had LDL-C measured within 6 months of PCI and 57% had LDL-C <70 mg/dl. After a median 3.2 years, the rates of cardiovascular events were 55.2/1,000 person-years for the LDL-C <70 mg/dl group, 60.3/1,000 person-years for 70 to <100 mg/dl, and 94.0/1,000 person-years for ≥100 mg/dl. The adjusted subdistribution hazard ratios for cardiovascular events were 1.17 (95% confidence interval: 1.09 to 1.26) for LDL-C of 70 to <100 mg/dl, and 1.78 (95% confidence interval: 1.64 to 1.94) for LDL-C ≥100 mg/dl when compared with LDL-C <70 mg/dl.

CONCLUSIONS

One in 2 patients had LDL-C measured within 6 months after PCI, and only 57% had LDL-C <70 mg/dl. Higher levels of LDL-C were associated with an increased incidence of late cardiovascular events. Improved cholesterol management after PCI should be considered to improve the outcomes of these patients.

Cardiac Stress Testing After Coronary Revascularization

Unless prompted by symptoms or change in clinical status, the appropriate use criteria consider cardiac stress testing (CST) within 2 years of percutaneous coronary intervention (PCI) and 5 years of coronary artery bypass grafting (CABG) to be rarely appropriate. Little is known regarding use and yield of CST after PCI or CABG. We studied 39,648 patients treated with coronary revascularization (29,497 PCI; 10,151 CABG) between April 2004 and March 2012 in Alberta, Canada. Frequency of CST between 60 days and 2 years after revascularization was determined from linked provincial databases. Yield was defined as subsequent rates of coronary angiography and revascularization after CST. Post PCI, 14,195 (48.1%) patients underwent CST between 60 days and 2 years, while post CABG, 4,469 (44.0%) patients underwent CST. Compared with patients not undergoing CST, patients undergoing CST were more likely to be of younger age, reside in an urban area, have higher neighborhood median household income, but less medical comorbidities. Among PCI patients undergoing CST, 5.2% underwent subsequent coronary angiography, and 2.6% underwent repeat revascularization within 60 days of CST. Rates of coronary angiography and repeat revascularization post-CST among CABG patients were 3.6% and 1.1%, respectively. Approximately one-half of patients undergo CST within 2 years of PCI or CABG in Alberta, Canada. Yield of CST is low, with only 1 out of 38 tested post-PCI patients and 1 out of 91 tested post-CABG patients undergoing further revascularization. In conclusion, additional research is required to determine patients most likely to benefit from CST after revascularization.

The Prognostic Value and Clinical Use of Myocardial Perfusion Scintigraphy in Asymptomatic Patients after Percutaneous Coronary Intervention

Background

The role of myocardial perfusion scintigraphy (MPS) in the follow-up of asymptomatic patients after percutaneous coronary intervention (PCI) is not established.

Objectives

To evaluate the prognostic value and clinical use of MPS in asymptomatic patients after PCI.

Methods

Patients who underwent MPS consecutively between 2008 and 2012 after PCI were selected. The MPS were classified as normal and abnormal, the perfusion scores, summed stress score (SSS), and summed difference score (SDS) were calculated and converted into percentage of total perfusion defect and ischemic defect. The follow-up was undertaken through telephone interviews and consultation with the Mortality Information System. Primary endpoints were death, cardiovascular death, and nonfatal acute myocardial infarction (AMI), and secondary endpoint was revascularization. Logistic regression and COX method were used to identify the predictors of events, and the value of p < 0.05 was considered statistically significant.

Results

A total of 647 patients were followed for 5.2 ± 1.6 years. 47% of MPS were normal, 30% were abnormal with ischemia, and 23% were abnormal without ischemia. There were 61 deaths, 27 being cardiovascular, 19 non-fatal AMI, and 139 revascularizations. The annual death rate was higher in those with abnormal perfusion without ischemia compared to the groups with ischemia and normal perfusion (3.3% × 2% × 1.2%, p = 0.021). The annual revascularization rate was 10.3% in the ischemia group, 3.7% in those with normal MPS, and 3% in those with abnormal MPS without ischemia. The independent predictors of mortality and revascularization were, respectively, total perfusion defect greater than 6%, and ischemic defect greater than 3%. Forty-two percent of the patients underwent MPS less than 2 years after PCI, and no significant differences were observed in relation to those who underwent it after that period.

Conclusion

Although this information is not contemplated in guidelines, in this study MPS was able to predict events in asymptomatic after PCI patients, regardless of when they were performed.