Danish study of Non-Invasive Testing in Coronary Artery Disease 3 (Dan-NICAD 3): study design of a controlled study on optimal diagnostic strategy

Clinical likelihood models calibrated against observed obstructive coronary artery disease on computed tomography angiography

AIMS

Models predicting the likelihood of obstructive coronary artery disease (CAD) on invasive coronary angiography exist. However, as stable patients with new-onset chest pain frequently have lower clinical likelihood and preferably undergo index testing by non-invasive tests such as coronary computed tomography angiography (CCTA), clinical likelihood models calibrated against observed obstructive CAD at CCTA are warranted. The aim was to develop CCTA-calibrated risk-factor- and coronary artery calcium score-weighted clinical likelihood models (i.e. RF-CLCCTA and CACS-CLCCTA models, respectively).

METHODS AND RESULTS

Based on age, sex, symptoms, and cardiovascular risk factors, an advanced machine learning algorithm utilized a training cohort (n = 38 269) of symptomatic outpatients with suspected obstructive CAD to develop both a RF-CLCCTA model and a CACS-CLCCTA model to predict observed obstructive CAD on CCTA. The models were validated in several cohorts (n = 28 340) and compared with a currently endorsed basic pre-test probability (Basic PTP) model. For both the training and pooled validation cohorts, observed obstructive CAD at CCTA was defined as >50% diameter stenosis. Observed obstructive CAD at CCTA was present in 6443 (22.7%) patients in the pooled validation cohort. While the Basic PTP underestimated the prevalence of observed obstructive CAD at CCTA, the RF-CLCCTA and CACS-CLCCTA models showed superior calibration. Compared with the Basic PTP model, the RF-CLCCTA and CACS-CLCCTA models showed superior discrimination (area under the receiver operating curves 0.71 [95% confidence interval (CI) 0.70-0.72] vs. 0.74 (95% CI 0.73-0.75) and 0.87 (95% CI 0.86-0.87), P < 0.001 for both comparisons).

CONCLUSION

CCTA-calibrated clinical likelihood models improve calibration and discrimination of observed obstructive CAD at CCTA.

Myocardial Perfusion Imaging With PET; A Head-to-Head Comparison of 82Rubidium Versus 15O-water Tracers Using Invasive Coronary Measurements as Reference

BACKGROUND

Myocardial perfusion imaging by positron emission tomography (PET) is recommended as a first-line test in stable patients with chest pain symptoms and as a selective second-line test after an abnormal coronary computed tomography angiography (CTA). It is, however, unknown whether the use of Rubidium-82 (82Rb) versus [15O]H2O (15O-water) affects the diagnostic performance in coronary artery disease (CAD). The aim of this study was to compare 82Rb-PET versus 15O-water-PET head-to-head for diagnosing obstructive CAD.

METHODS

The study included consecutive patients (n=1000) referred for CTA with symptoms suggestive of obstructive CAD. Patients with suspected stenosis based on CTA were referred for both 82Rb-PET, 15O-water-PET, and subsequently invasive coronary angiography (ICA), including 3-vessel fractional flow reserve and coronary flow reserve measurements.

RESULTS

In total, 196/270 (73%) patients with suspected stenosis on CTA completed 82Rb-PET, 15O-water-PET, and ICA. Myocardial blood flow measurements from 82Rb-PET and 15O-water-PET correlated strongly at rest (ρ, 0.62-0.69) but only moderately during hyperemia (ρ, 0.41-0.59). Only weak correlations were demonstrated between myocardial blood flow reserve by both PET tracers compared with ICA coronary flow reserve (ρ, 0.11-0.38). Hemodynamically obstructive CAD defined as ICA fractional flow reserve ≤0.80, was identified in 86/196 (44%) patients. Using predefined cutoffs, the diagnostic accuracies of 82Rb-PET versus 15O-water-PET were similar (sensitivity 69% [58-78%] versus 71% [60-80%], P=0.59; specificity 85% [76-91%] versus 77% [68-85%], P=0.12). Using ICA diameter stenoses >70% as a reference, only 48/196 (24%) patients had anatomically severe CAD, and 82Rb-PET and 15O-water-PET sensitivities increased to >85%.

CONCLUSIONS

For detection of obstructive CAD by PET myocardial perfusion imaging, 82Rb versus 15O-water have similar diagnostic performance.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04707859.

Elevated lipoprotein(a) levels are independently associated with the presence of significant coronary stenosis in de-novo patients with stable chest pain

BACKGROUND

The role of lipoprotein(a) (Lp(a)) in the risk-assessment of patients with de-novo stable chest pain is sparsely investigated. We assessed the association between Lp(a) concentration and the presence of coronary stenosis on coronary computed tomography (CT) angiography in a broad population of patients referred with stable chest pain.

METHODS

Lp(a) measurements and coronary CT angiography were performed in 4,346 patients with stable chest pain and no previous history of coronary artery disease. The patients were included in the trial program, the Danish study of Non-Invasive testing in Coronary artery disease, Dan-NICAD. The prevalence and odds ratios for stenosis were calculated comparing normal Lp(a) (< 20 nmol/l) with moderately elevated (20 to <125 nmol/l), high (125 to <200 nmol/l), and very high (≥200 nmol/l) Lp(a) concentrations in both univariate and multivariate analyses.

RESULTS

In total, 2,418 (55.6%), 1,276 (29.4%), 425 (9.8%), and 227 (5.2%) patients had normal, moderately elevated, high, and very high Lp(a) levels, respectively. The prevalences of coronary stenosis increased with increasing Lp(a) concentration (n = 569 (23.5%), n = 328 (25.7%), n = 129 (30.4%), and n = 77 (33.9%) in patients with normal, moderately elevated, high, and very high Lp(a), respectively). Likewise, the prevalence of patients with multivessel disease increased with increasing Lp(a) concentration (n = 252 (10.4%), n = 149 (11.7%), n = 61 (14.4%), and n = 41 (18.1%) in patients with normal, moderately elevated, high, and very high Lp(a), respectively). In an unadjusted model, odds ratios for stenosis increased with increasing Lp(a) concentrations odds ratio 95% CI: 1.12 (0.96-1.31), 1.42 (1.13-1.77), and 1.67 (1.24-2.22) for moderately elevated, high, and very high Lp(a) versus normal Lp(a), respectively). Adjustment for age, sex, and cardiovascular risk factors did not affect the association.

CONCLUSIONS

In stable, symptomatic patients without established coronary artery disease, Lp(a) levels are positively associated with the presence of coronary stenosis on coronary CT angiography. These findings may warrant using Lp(a) in the diagnostic management of patient with suspected coronary artery disease.

TRIAL REGISTRATION

The 3 studies within the Dan-NICAD program are registered on ClinicalTrials.gov: Dan-NICAD, NCT02264717, https://clinicaltrials.gov/study/NCT02264717?term=dan-nicad&rank=1. Dan-NICAD 2, NCT03481712, https://clinicaltrials.gov/study/NCT03481712?term=dan-nicad&rank=3. Dan-NICAD 3, NCT04707859, https://clinicaltrials.gov/study/NCT04707859?term=dan-nicad&rank=2.

Emerging Applications of Positron Emission Tomography in Coronary Artery Disease

Coronary artery disease remains the leading cause of morbidity and mortality worldwide. With the changing clinical manifestation and novel therapeutical options, precise disease phenotyping becomes increasingly important at the point of care. In the management of coronary artery disease, myocardial perfusion imaging (MPI) remains the cornerstone of clinical practice. Although traditionally MPI has been primarily performed with single photon emission computed tomography (SPECT), nowadays, given the changing spectrum of the disease, greater precision and additional assessment of myocardial blood flow are desired. Due to the fundamental advantages of PET over SPECT, i.e., higher spatial resolution, accurate attenuation correction for each scan, and higher count rates, the sensitivity and specificity of PET MPI are higher than those of SPECT MPI and are estimated to be approximately 90-92% vs. 83-88% and 81-87% vs. 70-76%, respectively, according to meta-analysis data. Consequently, over the past decade, we have witnessed an increased uptake of positron emission tomography (PET) MPI. With the improved spatial resolution, the ability to quantify myocardial blood flow, and the potential to depict the burden of coronary atherosclerosis with low-dose computed tomography, PET/CT is uniquely positioned to facilitate a comprehensive non-invasive assessment of disease, providing an opportunity for precision medicine. The wealth of data obtained during a single imaging session can be challenging to integrate at the time of image analysis. There has therefore been an increasing interest in developing predefined thresholds or variables (scores) which combine the multidimensional data acquired with PET MPI. Beyond MPI, PET can also serve for the assessment of disease activity at the atherosclerotic plaque level, further refining our understanding of the biology of coronary artery disease and providing hope for enhanced prediction of myocardial infarctions. In this narrative review, we present the current applications of PET MPI in coronary artery disease and focus specifically on two areas that have recently garnered considerable interest-the integration of multiparametric PET MPI data and coronary plaque activity PET imaging.

Association between symptom characteristics and disease severity in patients suspected of coronary artery disease

BACKGROUND

Discrepancies often exist between patient-reported symptoms and diagnostic test findings in patients with suspected obstructive coronary artery disease (CAD).

OBJECTIVES

To quantify the association between patient-reported symptoms and the diagnosis of severe stenosis in patients with suspected obstructive CAD.

METHODS

Two large-scale cohorts of patients with new-onset symptoms suggestive of obstructive CAD were evaluated. Chest discomfort was assessed by typicality, location, type, exertional/stress factors, and relief with rest/nitroglycerine. Patients underwent non-invasive diagnostic testing (coronary computed tomographic angiography (CCTA) or functional testing), followed by test-result-driven invasive coronary angiography (ICA). Severe stenosis was defined as ≥70 ​% diameter stenosis on ICA. Sensitivity analyses included CCTA stenosis, functional abnormalities, and revascularization.

RESULTS

Of 14,410 patients, 2093 (14.5 ​%) were referred for ICA, and 765 (5.3 ​%) were diagnosed with severe stenosis. Patients with typical angina (n ​= ​224) had higher odds of being diagnosed with severe stenosis on ICA (OR and 95 ​% CIs: 2.84 [2.40-3.34]) than those with atypical or non-anginal symptoms. In patients diagnosed with severe stenosis on ICA, those with exertional/stress factors (n ​= ​418; OR [95 ​% CI]: 2.50 [2.16-2.90]) and relief with rest/nitroglycerine (n ​= ​318, 2.28; [1.96-2.65]) had higher odds compared to those without. Patients reporting pressure or burning pain had higher odds of severe stenosis. Associations were consistent across sex and age groups, and sensitivity references.

CONCLUSIONS

Exertional/stress-related chest discomfort and relief with rest/nitroglycerine increased the odds of severe stenosis in patients with suspected CAD undergoing test-result-driven ICA, while location and type of chest pain were less associated, with no differences across sex or age groups.

Microvascular resistance reserve: impact on health status and myocardial perfusion after revascularization in chronic coronary syndrome

BACKGROUND AND AIMS

The microvascular resistance reserve (MRR) is a novel invasive index of the microcirculation, which is independent of epicardial stenoses, and has both diagnostic and prognostic implications. This study investigates whether MRR is associated with health status outcomes by revascularization in patients with moderate coronary stenoses.

METHODS

Consecutive patients with stable chest pain and moderate (30%-90% diameter) stenoses on invasive coronary angiography (n = 222) underwent invasive physiology assessment. Revascularization was performed according to guideline recommendations. At baseline and follow-up, health status and myocardial perfusion were assessed by the Seattle Angina Questionnaire (SAQ) and positron emission tomography. The primary endpoint was freedom from angina at follow-up with secondary endpoints including changes in health status by SAQ domains and myocardial perfusion by MRR and revascularization status. Low MRR was defined as ≤3.0.

RESULTS

Freedom from angina occurred in 38/173 patients. In multivariate analyses, MRR was associated with freedom from angina at follow-up (odds ratio 0.860, 95% confidence interval 0.740-0.987). By MRR and revascularization groups, patients with normal MRR who did not undergo revascularization, and patients with abnormal MRR who underwent revascularization, had improved health status of angina frequency [mean difference SAQ angina frequency score 8.5 (3.07-13.11) and 13.5 (2.82-23.16), respectively]. For both groups, health status of physical limitation [mean difference in SAQ physical limitation score 9.7 (4.79-11.93) and 8.7 (0.53-13.88), respectively] and general health status [mean difference in SAQ summary score 9.3 (5.18-12.50) and 10.8 (2.51-17.28), respectively] also improved. Only patients with abnormal MRR who underwent revascularization had improved myocardial perfusion.

CONCLUSIONS

In patients with moderate coronary stenoses, MRR seems to predict the symptomatic and perfusion benefit of revascularization.

CLINICAL TRIAL IDENTIFIERS

NCT03481712 and NCT04707859.

PET myocardial perfusion imaging: Trends, challenges, and opportunities

Various non-invasive images are used in clinical practice for the diagnosis and prognostication of chronic coronary syndromes. Notably, quantitative myocardial perfusion imaging (MPI) through positron emission tomography (PET) has seen significant technical advancements and a substantial increase in its use over the past two decades. This progress has generated an unprecedented wealth of clinical information, which, when properly applied, can diagnose and fine-tune the management of patients with different types of ischemic syndromes. This state-of-art review focuses on quantitative PET MPI, its integration into clinical practice, and how it holds up at the eyes of modern cardiac imaging and revascularization clinical trials, along with future perspectives.

Clinical Likelihood Prediction of Hemodynamically Obstructive Coronary Artery Disease in Patients With Stable Chest Pain

BACKGROUND

Selection for invasive angiography is recommended to be based on pretest probabilities (PTPs), and physiological measures of hemodynamical impairment by, for example, fractional flow reserve (FFR) should guide revascularization. The risk factor-weighted clinical likelihood (RF-CL) and coronary artery calcium score-weighted clinical likelihood (CACS-CL) models show superior discrimination of patients with suspected obstructive coronary artery disease (CAD), but validation against hemodynamic impairment is warranted.

OBJECTIVES

The aim of this study was to validate the RF-CL and CACS-CL models against hemodynamically obstructive CAD.

METHODS

Stable de novo chest pain patients (N = 4,371) underwent coronary computed tomography angiography and subsequently invasive coronary angiography with FFR measurements. Hemodynamically obstructive CAD was defined as invasive FFR ≤0.80 or high-grade stenosis by visual assessment (>90% diameter stenosis). For comparison, a guideline-endorsed basic PTP model was calculated based on age, sex, and symptom typicality. The RF-CL model additionally included the number of risk factors, and the CACS-CL model incorporated the coronary artery calcium score into the RF-CL.

RESULTS

In total, 447 of 4,371 (10.9%) patients had hemodynamically obstructive CAD. Both the RF-CL and CACS-CL models classified more patients with a very low clinical likelihood (≤5%) of obstructive CAD compared to the basic PTP model (33.0% and 53.7% vs 12.0%; P < 0.001) with a preserved low prevalence of hemodynamically obstructive CAD (<5% for all models). Against hemodynamically obstructive CAD, calibration and discrimination of the RF-CL and CACS-CL models were superior to the basic PTP model.

CONCLUSIONS

The RF-CL and CACS-CL models are well calibrated and superior to a currently recommended basic PTP model to predict hemodynamically obstructive CAD. (Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease [Dan-NICAD]; NCT02264717; Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease 2 [Dan-NICAD 2]; NCT03481712, Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease 3 [Dan-NICAD 3]; NCT04707859).