Future directions for cardiovascular disease comparative effectiveness research: report of a workshop sponsored by the National Heart, Lung, and Blood Institute

The Wider Considerations in Closing Chronic Disease Gaps - Focus on Heart Failure and Implementation

BACKGROUND

Heart failure (HF) is predominately a chronic disease. There are overlaps in HF and chronic disease research and care. Chronic disease and HF research are conducted with multiple goals. The overarching goal is "optimized patient outcomes at maximum costeffectiveness". However, observations on patients can come with many variables; thus, we see differences in clinical translation. This document discusses an argument for three important gaps common to HF and chronic disease, i.e., screening, self-management, and patient-reported outcomes (PRO), and provides a glance of how it could fit into the evidence tree. Pertinent arguments for a framework for health services and models of care are provided as a prelude to future consensus.

METHODOLOGY

1) A preliminary literature review to identify a taxonomy for cardiovascular research, and 2) a review of the published literature describing the translation of research studies into clinical practice for cardiovascular disorders. A spectrum from observational to large randomized controlled trials to post-marketing studies were identified.

DISCUSSION

A brief discussion on traditional research and differences focusing on screening, mixed methods research concepts, and chronic diseases models of care. Six steps to facilitate this: 1) Research design; 2) Research application (translation) i. routine ii. challenges; 3. Transforming research to translational level; 4. Funding and infrastructure; 5. Clinical Centres of Research Excellence (CCRE) and collaboration; 6. Governance and cost-effectiveness.

CONCLUSION

Implementation research that aims to link research findings to improved patient outcomes in an efficient and effective way is a neglected area. Skills required to perform implementation research are complex. Ways to maximize translational impacts for chronic disease research to clinical practice are described in a HF context.

Predictive value of CAC score combined with clinical features for obstructive coronary heart disease on coronary computed tomography angiography: a machine learning method

OBJECTIVE

We investigated the predictive value of clinical factors combined with coronary artery calcium (CAC) score based on a machine learning method for obstructive coronary heart disease (CAD) on coronary computed tomography angiography (CCTA) in individuals with atypical chest pain.

METHODS

The study included data from 1,906 individuals undergoing CCTA and CAC scanning because of atypical chest pain and without evidence for the previous CAD. A total of 63 variables including traditional cardiovascular risk factors, CAC score, laboratory results, and imaging parameters were used to build the Random forests (RF) model. Among all the participants, 70% were randomly selected to train the models on which fivefold cross-validation was done and the remaining 30% were regarded as a validation set. The prediction performance of the RF model was compared with two traditional logistic regression (LR) models.

RESULTS

The incidence of obstructive CAD was 16.4%. The area under the receiver operator characteristic (ROC) for obstructive CAD of the RF model was 0.841 (95% CI 0.820-0.860), the CACS model was 0.746 (95% CI 0.722-0.769), and the clinical model was 0.810 (95% CI 0.788-0.831). The RF model was significantly superior to the other two models (p < 0.05). Furthermore, the calibration curve and Hosmer-Lemeshow test showed that the RF model had good classification performance (p = 0.556). CAC score, age, glucose, homocysteine, and neutrophil were the top five important variables in the RF model.

CONCLUSION

RF model was superior to the traditional models in the prediction of obstructive CAD. In clinical practice, the RF model may improve risk stratification and optimize individual management.

Association of biological antirheumatic therapy with risk for type 2 diabetes: a retrospective cohort study in incident rheumatoid arthritis

OBJECTIVE

To explore possible associations of treatment with biological disease-modifying antirheumatic drugs (bDMARDs), including T-cell-based and interleukin-6 inhibition (IL-6i)-based therapies, and the risk for type 2 diabetes mellitus (T2DM) in patients with rheumatoid arthritis (RA).

STUDY DESIGN, SETTING AND PARTICIPANTS

Five treatment groups were selected from a United States Electronic Medical Records database of 283 756 patients with RA (mean follow-up, 5 years): never received bDMARD (No bDMARD, n=125 337), tumour necrosis factor inhibitors (TNFi, n=34 873), IL-6i (n=1884), T-cell inhibitors (n=5935) and IL-6i+T cell inhibitor abatacept (n=1213). Probability and risk for T2DM were estimated with adjustment for relevant confounders.

RESULTS

In the cohort of 169 242 patients with a mean 4.5 years of follow-up and a mean 641 200 person years of follow-up, the adjusted probability of developing T2DM was significantly lower in the IL-6i (probability, 1%; 95% CI 0.6 to 2.0), T-cell inhibitor (probability, 3%; 95% CI 2.3 to 3.3) and IL-6i+T cell inhibitor (probability, 2%; 95% CI 0.1 to 2.9) groups than in the No bDMARD (probability, 5%; 95% CI 4.6 to 4.9) and TNFi (probability, 4%; 95% CI 3.7 to 4.7) groups. Compared with No bDMARD, the IL-6i and IL-6i+T cell inhibitor groups had 37% (95% CI of HR 0.42 to 0.96) and 34% (95% CI of HR 0.46 to 0.93) significantly lower risk for T2DM, respectively; there was no significant difference in risk in the TNFi (HR 0.99; 95% CI 0.93 to 1.06) and T-cell inhibitor (HR 0.96; 95% CI 0.82 to 1.12) groups.

CONCLUSIONS

Treatment with IL-6i, with or without T-cell inhibitors, was associated with reduced risk for T2DM compared with TNFi or No bDMARDs; a less pronounced association was observed for the T-cell inhibitor abatacept.

Understanding Vulnerable Plaques: Current Status and Future Directions

The main cause of acute myocardial infarction is plaque rupture accompanied by superimposed coronary thrombosis. Thin-cap fibroatheromas (TCFAs) have been suggested as a type of lesion with a vulnerability that can cause plaque rupture. However, not only the existence of a TCFA but also the fine and complex interactions of other anatomical and hemodynamic factors, such as microcalcification in the fibrous cap, cholesterol crystal-induced inflammasome activation, the apoptosis of intraplaque macrophages, and endothelial shear stress distribution should precede a clinical event caused by plaque rupture. Recent studies are being conducted to identify these mechanisms through molecular imaging and hemodynamic assessment using computational fluid dynamics, which will result in better clinical results through selective coronary interventions.

Smartphone-Based Geofencing to Ascertain Hospitalizations

BACKGROUND

Ascertainment of hospitalizations is critical to assess quality of care and the effectiveness and adverse effects of various therapies. Smartphones, mobile geolocators that are ubiquitous, have not been leveraged to ascertain hospitalizations. Therefore, we evaluated the use of smartphone-based geofencing to track hospitalizations.

METHODS AND RESULTS

Participants aged ≥18 years installed a mobile application programmed to geofence all hospitals using global positioning systems and cell phone tower triangulation and to trigger a smartphone-based questionnaire when located in a hospital for ≥4 hours. An in-person study included consecutive consenting patients scheduled for electrophysiology and cardiac catheterization procedures. A remote arm invited Health eHeart Study participants who consented and engaged with the study via the internet only. The accuracy of application-detected hospitalizations was confirmed by medical record review as the reference standard. Of 22 eligible in-person patients, 17 hospitalizations were detected (sensitivity 77%; 95% confidence interval, 55%-92%). The length of stay according to the application was positively correlated with the length of stay ascertained via the electronic medical record (r=0.53; P=0.03). In the remote arm, the application was downloaded by 3443 participants residing in all 50 US states; 243 hospital visits at 119 different hospitals were detected through the application. The positive predictive value for an application-reported hospitalization was 65% (95% confidence interval, 57%-72%).

CONCLUSIONS

Mobile application-based ascertainment of hospitalizations can be achieved with modest accuracy. This first proof of concept may ultimately be applicable to geofencing other types of prespecified locations to facilitate healthcare research and patient care.

Comparative Effectiveness Trials of Imaging-Guided Strategies in Stable Ischemic Heart Disease

The evaluation of patients with suspected stable ischemic heart disease is among the most common diagnostic evaluations with nearly 20 million imaging and exercise stress tests performed annually in the United States. Over the past decade, there has been an evolution in imaging research with an ever-increasing focus on larger registries and randomized trials comparing the effectiveness of varying diagnostic algorithms. The current review highlights recent randomized trial evidence with a particular focus comparing the effectiveness of cardiac imaging procedures within the stable ischemic heart disease evaluation for coronary artery disease detection, angina, and other quality of life measures, and major clinical outcomes. Also highlighted are secondary analyses from these trials on the economic findings related to comparative cost differences across diagnostic testing strategies.

Plaque imaging with CT-a comprehensive review on coronary CT angiography based risk assessment

CT based technologies have evolved considerably in recent years. Coronary CT angiography (CTA) provides robust assessment of coronary artery disease (CAD). Early coronary CTA imaging-as a gate-keeper of invasive angiography-has focused on the presence of obstructive stenosis. Coronary CTA is currently the only non-invasive imaging modality for the evaluation of non-obstructive CAD, which has been shown to contribute to adverse cardiac events. Importantly, improved spatial resolution of CT scanners and novel image reconstruction algorithms enable the quantification and characterization of atherosclerotic plaques. State-of-the-art CT imaging can therefore reliably assess the extent of CAD and differentiate between various plaque features. Recent studies have demonstrated the incremental prognostic value of adverse plaque features over luminal stenosis. Comprehensive coronary plaque assessment holds potential to significantly improve individual risk assessment incorporating adverse plaque characteristics, the extent and severity of atherosclerotic plaque burden. As a result, several coronary CTA based composite risk scores have been proposed recently to determine patients at high risk for adverse events. Coronary CTA became a promising modality for the evaluation of functional significance of coronary lesions using CT derived fractional flow reserve (FFR-CT) and/or rest/dynamic myocardial CT perfusion. This could lead to substantial reduction in unnecessary invasive catheterization procedures and provide information on ischemic burden of CAD. Discordance between the degree of stenosis and ischemia has been recognized in clinical landmark trials using invasive FFR. Both lesion stenosis and composition are possibly related to myocardial ischemia. The evaluation of lesion-specific ischemia using combined functional and morphological plaque information could ultimately improve the diagnostic performance of CTA and thus patient care. In this review we aimed to summarize current evidence on comprehensive coronary artery plaque assessment using coronary CTA.

Validity of Cardiovascular Data From Electronic Sources: The Multi-Ethnic Study of Atherosclerosis and HealthLNK

BACKGROUND

Understanding the validity of data from electronic data research networks is critical to national research initiatives and learning healthcare systems for cardiovascular care. Our goal was to evaluate the degree of agreement of electronic data research networks in comparison with data collected by standardized research approaches in a cohort study.

METHODS

We linked individual-level data from MESA (Multi-Ethnic Study of Atherosclerosis), a community-based cohort, with HealthLNK, a 2006 to 2012 database of electronic health records from 6 Chicago health systems. To evaluate the correlation and agreement of blood pressure in HealthLNK in comparison with in-person MESA examinations, and body mass index in HealthLNK in comparison with MESA, we used Pearson correlation coefficients and Bland-Altman plots. Using diagnoses in MESA as the criterion standard, we calculated the performance of HealthLNK for hypertension, obesity, and diabetes mellitus diagnosis by using International Classification of Diseases, Ninth Revision codes and clinical data. We also identified potential myocardial infarctions, strokes, and heart failure events in HealthLNK and compared them with adjudicated events in MESA.

RESULTS

Of the 1164 MESA participants enrolled at the Chicago Field Center, 802 (68.9%) participants had data in HealthLNK. The correlation was low for systolic blood pressure (0.39; P<0.0001). In comparison with MESA, HealthLNK overestimated systolic blood pressure by 6.5 mm Hg (95% confidence interval, 4.2-7.8). There was a high correlation between body mass index in MESA and HealthLNK (0.94; P<0.0001). HealthLNK underestimated body mass index by 0.3 kg/m² (95% confidence interval, -0.4 to -0.1). With the use of International Classification of Diseases, Ninth Revision codes and clinical data, the sensitivity and specificity of HealthLNK queries for hypertension were 82.4% and 59.4%, for obesity were 73.0% and 89.8%, and for diabetes mellitus were 79.8% and 93.3%. In comparison with adjudicated cardiovascular events in MESA, the concordance rates for myocardial infarction, stroke, and heart failure were, respectively, 41.7% (5/12), 61.5% (8/13), and 62.5% (10/16).

CONCLUSIONS

These findings illustrate the limitations and strengths of electronic data repositories in comparison with information collected by traditional standardized epidemiological approaches for the ascertainment of cardiovascular risk factors and events.

Clinical indications for coronary artery calcium scoring in asymptomatic patients: Expert consensus statement from the Society of Cardiovascular Computed Tomography

This expert consensus statement summarizes the available data regarding the prognostic value of CAC in the asymptomatic population and its ability to refine individual risk prediction, addresses the limitations identified in the current traditional risk factor-based treatment strategies recommended by the 2013 ACC/AHA Prevention guidelines including use of the Pooled Cohort Equations (PCE), and the US Preventive Services Task Force (USPSTF) Recommendation Statement for Statin Use for the Primary Prevention of Cardiovascular Disease in Adults. It provides CAC based treatment recommendations both within the context of the shared decision making model espoused by the 2013 ACC/AHA Prevention guidelines and independent of these guidelines.

Robotic surgery is the optimal approach for mitral surgery

This report presented an overview of the patient selection, technical considerations and clinical evidence for robotic mitral valve surgery. A review of comparative outcomes to medical therapy, sternotomy approach, and the MitraClip device suggested that robotic mitral valve surgery is safe and effective in specialized centres. Potential benefits include a reliable and durable repair, with reduced perioperative morbidity and improved quality of life. Future studies should aim to delineate mid- and long-term clinical and echocardiographic outcomes following robotic mitral valve repair compared to the conventional sternotomy approach.

MRI/optical dual-modality imaging of vulnerable atherosclerotic plaque with an osteopontin-targeted probe based on Fe3O4 nanoparticles

Rupture of vulnerable atherosclerotic plaque is the major pathological cause of luminal thrombosis in acute coronary syndromes. Since foamy macrophages have been identified as a prominent component in vulnerable atherosclerotic lesions and osteopontin (OPN) is reported to be highly expressed in foamy macrophages, OPN could be a potential target for vulnerable atherosclerotic plaque imaging. The current study designed an OPN-specific MRI/optical dual-modality probe to detect vulnerable plaques. Fluorescence imaging revealed that 24 h after injection of the Cy5.5-OPN-DMSA-MNPs (COD-MNPs), the atherosclerotic plaques in carotid artery exhibited significant higher signals in high fat diet (HFD) fed mice in comparison to the group injected with Cy5.5-IgG-DMSA-MNPs (CID-MNPs) or normal diet fed group injected with COD-MNPs (1.87 ± 0.19 × 10¹⁰ vs. 0.74 ± 0.04 × 10¹⁰, 0.73 ± 0.03 × 10¹⁰ p/sec/cm²/sr, P < 0.05). Meanwhile, MRI displayed stronger T₂ contrast enhancement 24 h post-injection at the area of atherosclerotic plaques in the carotid of HFD fed group injected with COD-MNPs than group injected with CID-MNPs or normal diet fed group injected with COD-MNPs (post/pre signal ratio: 0.64 ± 0.04 vs. 0.95 ± 0.02, 0.98 ± 0.01, P < 0.05). As a dual-modality molecular probe, the resulting COD-MNPs conjugates exhibit promising potentials for noninvasive detection of vulnerable atherosclerotic plaque in vivo.

Timely publication and sharing of trial data: opportunities and challenges for comparative effectiveness research in cardiovascular disease

There is growing enthusiasm for the timely publication and sharing of clinical trial data. The rationale for open access includes greater transparency, reproducibility, and efficiency of the research enterprise. In cardiovascular diseases, routinely sharing clinical trial data would create opportunities for undertaking comparative effectiveness research, providing much needed evidence on how different interventions compare to each other on key outcomes. Access to individual patient-level data would strengthen the validity of such research. Novel methodological approaches like network meta-analyses using individual patient-level data could reliably compare interventions that have not been compared with each other in head-to-head trials. However, there are significant practical, methodological, financial, and legal challenges to this utopian open access that need to be continually addressed. Sharing clinical trial data openly will only occur when the previously tolerated process of clinical research involving direct ownership and secrecy is abandoned for a new culture in which medical science is open to all of its stakeholders. With this new culture, data will be accessible, reanalysis will be considered commonplace, and comparative effectiveness research through novel synthesis approaches, such as network meta-analyses, can thrive-as long as measures are taken to adequately ensure the goal remains to promote public health.

Coronary Computed Tomography Angiography Versus Radionuclide Myocardial Perfusion Imaging in Patients With Chest Pain Admitted to Telemetry: A Randomized Trial

BACKGROUND

The role of coronary computed tomography angiography (CCTA) in the management of symptomatic patients suspected of having coronary artery disease is expanding. However, prospective intermediate-term outcomes are lacking.

OBJECTIVE

To compare CCTA with conventional noninvasive testing.

DESIGN

Randomized, controlled comparative effectiveness trial. (ClinicalTrials.gov: NCT00705458).

SETTING

Telemetry-monitored wards of an inner-city medical center.

PATIENTS

400 patients with acute chest pain (mean age, 57 years); 63% women; 54% Hispanic and 37% African-American; and low socioeconomic status.

INTERVENTION

CCTA or radionuclide stress myocardial perfusion imaging (MPI).

MEASUREMENTS

The primary outcome was cardiac catheterization not leading to revascularization within 1 year. Secondary outcomes included length of stay, resource utilization, and patient experience. Safety outcomes included death, major cardiovascular events, and radiation exposure.

RESULTS

Thirty (15%) patients who had CCTA and 32 (16%) who had MPI underwent cardiac catheterization within 1 year. Fifteen (7.5%) and 20 (10%) of these patients, respectively, did not undergo revascularization (difference, -2.5 percentage points [95% CI, -8.6 to 3.5 percentage points]; hazard ratio, 0.77 [CI, 0.40 to 1.49]; P = 0.44). Median length of stay was 28.9 hours for the CCTA group and 30.4 hours for the MPI group (P = 0.057). Median follow-up was 40.4 months. For the CCTA and MPI groups, the incidence of death (0.5% versus 3%; P = 0.12), nonfatal cardiovascular events (4.5% versus 4.5%), rehospitalization (43% versus 49%), emergency department visit (63% versus 58%), and outpatient cardiology visit (23% versus 21%) did not differ. Long-term, all-cause radiation exposure was lower for the CCTA group (24 versus 29 mSv; P < 0.001). More patients in the CCTA group graded their experience favorably (P = 0.001) and would undergo the examination again (P = 0.003).

LIMITATION

This was a single-site study, and the primary outcome depended on clinical management decisions.

CONCLUSION

The CCTA and MPI groups did not significantly differ in outcomes or resource utilization over 40 months. Compared with MPI, CCTA was associated with less radiation exposure and with a more positive patient experience.

PRIMARY FUNDING SOURCE

American Heart Association.

The myth of the "vulnerable plaque": transitioning from a focus on individual lesions to atherosclerotic disease burden for coronary artery disease risk assessment

The cardiovascular science community has pursued the quest to identify vulnerable atherosclerotic plaque in patients for decades, hoping to prevent acute coronary events. However, despite major advancements in imaging technology that allow visualization of rupture-prone plaques, clinical studies have not demonstrated improved risk prediction compared with traditional approaches. Considering the complex relationship between plaque rupture and acute coronary event risk suggested by pathology studies and confirmed by clinical investigations, these results are not surprising. This review summarizes the evidence supporting a multifaceted hypothesis of the natural history of atherosclerotic plaque rupture. Managing patients at risk of acute coronary events mandates a greater focus on the atherosclerotic disease burden rather than on features of individual plaques.

Cardiac resynchronization therapy: implant rates, temporal trends and relationships with heart failure epidemiology

BACKGROUND

Consensus guidelines define indications for cardiac resynchronization therapy (CRT), but the variability in implant rates in 'real world' clinical practice, as well as the relationship with the epidemiology of heart failure are not defined.

METHODS AND RESULTS

In Emilia-Romagna, an Italian region with around 4.4 million inhabitants, a registry was instituted to collect data on implanted devices for CRT, with (CRT-D) or without defibrillation (CRT-P) capabilities. Data from all consecutive patients resident in this region who underwent a first implant of a CRT device in years 2006-2010 were collected and standardized (considering each of the nine provinces of the region). The number of CRT implants increased progressively, with a 71% increase in 2010 compared to 2006. Between 84 and 90% of implants were with CRT-D devices. The variability in standardized implant rates among the provinces was substantial and the ratio between the provinces with the highest and the lowest implant rates was always greater than 2. Considering prevalent cases of heart failure in the period 2006-2010, the proportion of patients implanted with CRT per year ranged between 0.23 and 0.30%.

CONCLUSIONS

The application in 'real world' clinical practice of CRT in heart failure is quite heterogeneous, with substantial variability even among areas belonging to the same region, with the need to make the access to this treatment more equitable. Despite the increased use of CRT, its overall rate of adoption is low, if a population of prevalent heart failure patients is selected on the basis of administrative data on hospitalizations.

PROspective Multicenter Imaging Study for Evaluation of chest pain: rationale and design of the PROMISE trial

BACKGROUND

Suspected coronary artery disease (CAD) is one of the most common, potentially life-threatening diagnostic problems clinicians encounter. However, no large outcome-based randomized trials have been performed to guide the selection of diagnostic strategies for these patients.

METHODS

The PROMISE study is a prospective, randomized trial comparing the effectiveness of 2 initial diagnostic strategies in patients with symptoms suspicious for CAD. Patients are randomized to either (1) functional testing (exercise electrocardiogram, stress nuclear imaging, or stress echocardiogram) or (2) anatomical testing with ≥64-slice multidetector coronary computed tomographic angiography. Tests are interpreted locally in real time by subspecialty certified physicians, and all subsequent care decisions are made by the clinical care team. Sites are provided results of central core laboratory quality and completeness assessment. All subjects are followed up for ≥1 year. The primary end point is the time to occurrence of the composite of death, myocardial infarction, major procedural complications (stroke, major bleeding, anaphylaxis, and renal failure), or hospitalization for unstable angina.

RESULTS

More than 10,000 symptomatic subjects were randomized in 3.2 years at 193 US and Canadian cardiology, radiology, primary care, urgent care, and anesthesiology sites.

CONCLUSION

Multispecialty community practice enrollment into a large pragmatic trial of diagnostic testing strategies is both feasible and efficient. The PROMISE trial will compare the clinical effectiveness of an initial strategy of functional testing against an initial strategy of anatomical testing in symptomatic patients with suspected CAD. Quality of life, resource use, cost-effectiveness, and radiation exposure will be assessed.

The cost implications of an early versus delayed invasive strategy in Acute Coronary Syndromes: the TIMACS study

BACKGROUND

The Timing of Intervention in Acute Coronary Syndromes (TIMACS) trial demonstrated that early invasive intervention (within 24 hours) was similar to a delayed approach (after 36 hours) overall but improved outcomes were seen in patients at high risk. However, the cost implications of an early versus delayed invasive strategy are unknown.

METHODS AND RESULTS

A third-party perspective of direct cost was chosen and United States Medicare costs were calculated using average diagnosis related grouping (DRG) units. Direct medical costs included those of the index hospitalization (including clinical, procedural and hospital stay costs) as well as major adverse cardiac events during 6 months of follow-up. Sensitivity and sub-group analyses were performed. The average total cost per patient in the early intervention group was lower compared with the delayed intervention group (-$1170; 95% CI -$2542 to $202). From the bootstrap analysis (5000 replications), the early invasive approach was associated with both lower costs and better clinical outcomes regarding death/myocardial infarction (MI)/stroke in 95.1% of the cases (dominant strategy). In high-risk patients (GRACE score ≥141), the net reduction in cost was greatest (-$3720; 95% CI -$6270 to -$1170). Bootstrap analysis revealed 99.8% of cases were associated with both lower costs and better clinical outcomes (death/MI/stroke).

LIMITATIONS

We were unable to evaluate the effect of community care and investigations without hospitalization (office visits, non-invasive testing, etc). Medication costs were not captured. Indirect costs such as loss of productivity and family care were not included.

CONCLUSIONS

An early invasive management strategy is as effective as a delayed approach and is likely to be less costly in most patients with acute coronary syndromes.

Use of coronary artery calcium testing to guide aspirin utilization for primary prevention: estimates from the multi-ethnic study of atherosclerosis

BACKGROUND

Aspirin for the primary prevention of coronary heart disease (CHD) is only recommended for individuals at high risk for CHD although the majority of CHD events occur in individuals who are at low to intermediate risk.

METHODS AND RESULTS

To estimate the potential of coronary artery calcium (CAC) scoring to guide aspirin use for primary prevention of CHD, we studied 4229 participants from the Multi-Ethnic Study of Atherosclerosis who were not on aspirin at baseline and were free of diabetes mellitus. Using data from median 7.6-year follow-up, 5-year number-needed-to-treat estimations were calculated by applying an 18% relative CHD reduction to the observed event rates. This was contrasted to 5-year number-needed-to-harm estimations based on the risk of major bleeding reported in an aspirin meta-analysis. Results were stratified by a 10% 10-year CHD Framingham Risk Score (FRS). Individuals with CAC≥100 had an estimated net benefit with aspirin regardless of their traditional risk status (estimated 5-year number needed to treat of 173 for individuals <10% FRS and 92 for individuals ≥10% FRS, estimated 5-year number needed to harm of 442 for a major bleed). Conversely, individuals with zero CAC had unfavorable estimations (estimated 5-year number needed to treat of 2036 for individuals <10% FRS and 808 for individuals ≥10% FRS, estimated 5-year number needed to harm of 442 for a major bleed). Sex-specific and age-stratified analyses showed similar results.

CONCLUSIONS

For the primary prevention of CHD, Multi-Ethnic Study of Atherosclerosis participants with CAC≥100 had favorable risk/benefit estimations for aspirin use while participants with zero CAC were estimated to receive net harm from aspirin.

Rationale and design of a randomized trial comparing initial stress echocardiography versus coronary CT angiography in low-to-intermediate risk emergency department patients with chest pain

BACKGROUND

Comparative effectiveness research (CER) has become a major focus of cardiovascular disease investigation to optimize diagnosis and treatment paradigms and decrease healthcare expenditures. Acute chest pain is a highly prevalent reason for evaluation in the Emergency Department (ED) that results in hospital admission for many patients and excess expense. Improvement in noninvasive diagnostic algorithms can potentially reduce unnecessary admissions.

OBJECTIVE

To compare the performance of treadmill stress echocardiography (SE) and coronary computed tomography angiography (CTA) in ED chest pain patients with low-to-intermediate risk of significant coronary artery disease.

DESIGN

This is a single-center, randomized controlled trial (RCT) comparing SE and CTA head-to-head as the initial noninvasive imaging modality. The primary outcome measured is the incidence of hospitalization. The study is powered to detect a reduction in admissions from 28% to 15% with a sample size of 400. Secondary outcomes include length of stay in the ED/hospital and estimated cost of care. Safety outcomes include subsequent visits to the ED and hospitalizations, as well as major adverse cardiovascular events at 30 days and 1 year. Patients who do not meet study criteria or do not consent for randomization are offered entry into an observational registry.

CONCLUSIONS

This RCT will add to our understanding of the roles of different imaging modalities in triaging patients with suspected angina. It will increase the CER evidence base comparing SE and CTA and provide insight into potential benefits and limitations of appropriate use of treadmill SE in the ED.

The role of cardiovascular magnetic resonance imaging and computed tomography angiography in suspected non-ST-elevation myocardial infarction patients: design and rationale of the CARdiovascular Magnetic rEsoNance imaging and computed Tomography Angiography (CARMENTA) trial

BACKGROUND

Although high-sensitivity cardiac troponin (hs-cTn) substantially improves the early detection of myocardial injury, it lacks specificity for acute myocardial infarction (MI). In suspected non-ST-elevation MI, invasive coronary angiography (ICA) remains necessary to distinguish between acute MI and noncoronary myocardial disease (eg, myocarditis), unnecessarily subjecting the latter to ICA and associated complications. This trial investigates whether implementing cardiovascular magnetic resonance (CMR) or computed tomography angiography (CTA) early in the diagnostic process may help to differentiate between coronary and noncoronary myocardial disease, thereby preventing unnecessary ICA.

STUDY DESIGN

In this prospective, single-center, randomized controlled clinical trial, 321 consecutive patients with acute chest pain, elevated hs-cTnT, and nondiagnostic electrocardiogram are randomized to 1 of 3 strategies: (1) CMR, or (2) CTA early in the diagnostic process, or (3) routine clinical management. In the 2 investigational arms of the study, results of CMR or CTA will guide further clinical management. It is expected that noncoronary myocardial disease is detected more frequently after early noninvasive imaging as compared with routine clinical management, and unnecessary ICA will be prevented. The primary end point is the total number of patients undergoing ICA during initial admission. Secondary end points are 30-day and 1-year clinical outcome (major adverse cardiac events and major procedure-related complications), time to final diagnosis, quality of life, and cost-effectiveness.

CONCLUSION

The CARMENTA trial investigates whether implementing CTA or CMR early in the diagnostic process in suspected non-ST-elevation MI based on elevated hs-cTnT can prevent unnecessary ICA as compared with routine clinical management, with no detrimental effect on clinical outcome.

Epidemiologic and statistical methods for comparative effectiveness research

Observational methods are evolving in response to the widespread availability of data from clinical registries, electronic health records, and administrative databases. These approaches will never eliminate the need for randomized trials, but clearly have a role in evaluating the effect of therapies in unselected populations treated in routine practice.

Why Does Primary Angioplasty Not Work in Registries? Quantifying the Susceptibility of Real-World Comparative Effectiveness Data to Allocation Bias

Background—

Meta-analysis of registries (comparative effectiveness research) shows that primary angioplasty and fibrinolysis have equivalent real-world survival. Yet, randomized, controlled trials consistently find primary angioplasty superior. Can unequal allocation of higher-risk patients in registries have masked primary angioplasty benefit?

Methods and Results—

First, we constructed a model to demonstrate the potential effect of allocation bias. We then analyzed published registries (55022 patients) for allocation of higher-risk patients (Killip class ≥1) to determine whether the choice of reperfusion therapy was affected by the risk level of the patient. Meta-regression was used to examine the relationship between differences in allocation of high-risk patient to primary angioplasty or fibrinolysis and mortality. Initial modeling suggested that registry outcomes are sensitive to allocation bias of high-risk patients. Across the registries, the therapy receiving excess high-risk patients had worse mortality. Unequal distribution of high-risk status accounted for most of the between-registry variance (adjusted R 2 meta =83.1%). Accounting for differential allocation of higher-risk patients, primary angioplasty gave 22% lower mortality (odds ratio, 0.78; 95% confidence interval, 0.64–0.97; P =0.029). We derive a formula, called the number needed to abolish, highlighting situations in which comparative effectiveness studies are particularly vulnerable to this bias.

Conclusions—

In ST-segment elevation myocardial infarction, clinicians’ preference for management of a few high-risk patients can shift mortality substantially. Comparative effectiveness research in any disease is vulnerable to this, especially diseases with an immediately identifiable high-risk subgroup that clinicians prefer to allocate to 1 therapy. For this reason, preliminary indications from registry-based comparative effectiveness research should be definitively tested by randomized, controlled trials.