Sex and age differences in the association of heart rate responses to adenosine and myocardial ischemia in patients undergoing myocardial perfusion imaging

BACKGROUND

In light of growing cardiovascular mortality rates observed in young women, sexual dimorphism in cardiac autonomic nervous control is gaining increasing attention. Heart rate responses to adenosine mirror autonomic activity and may carry important prognostic information.

METHODS AND RESULTS

Hemodynamic changes during adenosine stress were retrospectively analysed in a propensity-matched cohort of 1932 consecutive patients undergoing myocardial perfusion single-photon-emission computed tomography (MPI-SPECT). Heart rate (HR) and systolic blood pressure (SBP) increased during adenosine infusion (P < 0.001). The increase in SBP and HR (heart rate reserve, HRR), was significantly more pronounced in women compared with men (P < 0.05). Patients ≤ 55 years had a higher HRR compared with patients > 55 years (46.8% vs 37.5%, P = 0.015). Women ≤ 55 years with a reversible perfusion defect on MPI-SPECT exhibited the highest HRR (89.2%), while age-matched men showed a blunted HR response to adenosine (26.4%, P = 0.01). Accordingly, age and an interaction term of female sex and increased HRR were identified as significant predictors of myocardial ischemia in a multiple regression analysis (OR 1.4, 95% CI 1.02-1.9, P = 0.038).

CONCLUSION

HRR during adenosine infusion is influenced by age and sex. Our data suggest a stronger, sympathetic-driven, hemodynamic response to adenosine in younger women with myocardial ischemia.

Ultra-low-dose computed tomography for attenuation correction of cadmium-zinc-telluride single photon emission computed tomography myocardial perfusion imaging

BACKGROUND

The applicability of ultra-low-dose computed tomography (CT) for attenuation correction (AC) of single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) remains elusive.

METHODS AND RESULTS

One-hundred patients underwent one-day 99mTc-tetrofosmin stress-rest MPI and non-contrast enhanced cardiac CT with 120, 80, and 70 kilovolt peak (kVp) tube voltage and tube current of 200 milliamperes for creation of AC maps. Normalized percent myocardial uptake from SPECT-MPI using 80 kVp scans for AC showed excellent correlation vs AC from 120 kVp scans for stress [intraclass correlation (ICC) = 0.988, 95% CI = 0.986-0.989, P < .001] and rest (ICC = 0.985, 95% CI = 0.983-0.987, P < .001) with narrow Bland-Altman limits of agreement (BA-LA) (- 5.3% to 4.5% and - 5.4% to 4.4%, respectively) and minimal bias (- 0.4% and - 0.5%, respectively). Correlation of AC SPECT-MPI based on 70 vs 120 kVp scans was excellent for stress (ICC = 0.988, 95% CI = 0.986-0.989, P < .001) and rest (ICC = 0.986, 95% CI = 0.984-0.987, P < .001) with narrow BA-LA (- 5.3% to 4.4% and - 5.2% to 4.5%, respectively) and small bias (- 0.4% and - 0.3%, respectively). Mean effective radiation dose for the 120, 80 and 70 kVp scans were 0.58 ± 0.07, 0.19 ± 0.02, and 0.12 ± 0.01 mSv, respectively.

CONCLUSIONS

Attenuation maps for MPI obtained from ultra-low radiation dose CT scans are interchangeable with attenuation maps from standard-dose CT while offering a substantial reduction in radiation dose exposure.

Coronary artery volume index: a novel CCTA-derived predictor for cardiovascular events

Coronary computed tomography angiography (CCTA) provides critical prognostic information on plaque burden and stenosis severity of coronary arteries. We aimed to investigate the long-term prognostic value of coronary artery volume per myocardial mass as a potential new imaging parameter. Consecutive patients with suspected coronary artery disease (CAD) were included. Coronary artery volume index (CAVi) was defined as volume over myocardial mass. Additionally, obstructive CAD (≥ 70% stenosis) and segment severity score (SSS: sum of all segments scored according to lesion severity with 0 = no lesion, 1 = narrowing < 50%, 2 = stenosis 50-69% and 3 = stenosis ≥ 70%) were evaluated. Major adverse cardiovascular events (MACE) were defined as cardiac death, non-fatal myocardial infarction or revascularization. The association of CAVi with MACE was evaluated using Cox regression hazards ratios (HR) and Kaplan Meier curves. In a total of 325 patients, 36 (11.1%) patients experienced MACE during the mean follow-up of 5.4 ± 1.7 years. Patients with low-CAVi (< 27.9 mm³/g) experienced more MACE than patients with high-CAVI (17.2% versus 4.5%, p < 0.001, Kaplan Meier curve p = 0.001). SSS, obstructive CAD and low-CAVi were all significant predictors of MACE in univariable analysis (HR 1.14, 95% CI 1.09-1.19, p < 0.001; HR 5.51, 95% CI 2.86-10.60, p < 0.001; and HR 3.79, 95% CI 1.66-8.65, p = 0.002, respectively). CAVi maintained significant association with MACE when adjusted to SSS (CAVi HR 2.43, 95% CI 1.02-5.75, p = 0.04) or obstructive CAD (CAVi HR 2.4, 95% CI 1.002-5.75, p = 0.049). CAVi could further risk stratify patients without obstructive CAD when stratifying patients according to obstructive CAD (Kaplan-Meier curve p = 0.049). CAVi is a novel CCTA-derived imaging parameter, yielding independent prognostic value over stenosis and plaque burden.

Subclinical coronary artery disease in Swiss HIV-positive and HIV-negative persons

Aims

HIV-positive persons have increased cardiovascular event rates but data on the prevalence of subclinical atherosclerosis compared with HIV-negative persons are not uniform. We assessed subclinical atherosclerosis utilizing coronary artery calcium (CAC) scoring and coronary computed tomography angiography (CCTA) in 428 HIV-positive participants of the Swiss HIV Cohort Study and 276 HIV-negative controls concurrently referred for clinically indicated CCTA.

Methods and results

We assessed the association of HIV infection, cardiovascular risk profile, and HIV-related factors with subclinical atherosclerosis in univariable and multivariable analyses. HIV-positive participants (median duration of HIV infection, 15 years) were younger than HIV-negative participants (median age 52 vs. 56 years; P < 0.01) but had similar median 10-year Framingham risk scores (9.0% vs. 9.7%; P = 0.40). The prevalence of CAC score >0 (53% vs. 56.2%; P = 0.42) and median CAC scores (47 vs. 47; P = 0.80) were similar, as was the prevalence of any, non-calcified/mixed, and high-risk plaque. In multivariable adjusted analysis, HIV-positive participants had a lower prevalence of calcified plaque than HIV-negative participants [36.9% vs. 48.6%, P < 0.01; adjusted odds ratio (aOR) 0.57; 95% confidence interval (CI) 0.40-0.82; P < 0.01], lower coronary segment severity score (aOR 0.72; 95% CI 0.53-0.99; P = 0.04), and lower segment involvement score (aOR 0.71, 95% CI 0.52-0.97; P = 0.03). Advanced immunosuppression was associated with non-calcified/mixed plaque (aOR 1.97; 95% CI 1.09-3.56; P = 0.02).

Conclusion

HIV-positive persons in Switzerland had a similar degree of non-calcified/mixed plaque and high-risk plaque, and may have less calcified coronary plaque, and lower coronary atherosclerosis involvement and severity scores than HIV-negative persons with similar Framingham risk scores.

Sex-dependent association between inflammation, neural stress responses, and impaired myocardial function

PURPOSE

Evidence to date has failed to reveal unique female determinants of cardiovascular disease. However, a strong association was recently observed between increased metabolic activity in the amygdala, a neural centre involved in the processing of emotions, and impaired myocardial function in women, but not in men. Given the stronger immune responses in females, we sought to retrospectively investigate the interaction between inflammation, perceived stress, and myocardial injury.

METHODS

Overall, 294 patients (mean age 66.9 ± 10.0 years, 28.6% women) underwent both, ^99mTc-tetrofosmin single-photon emission computed tomography myocardial perfusion imaging and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography for the assessment of cardiac function, bone marrow metabolism (surrogate marker of inflammation), and resting amygdalar activity.

RESULTS

A positive association was found between amygdalar metabolism and ¹⁸F-FDG bone marrow uptake in women (r = 0.238, p = 0.029), but not in men (r = 0.060, p = 0.385). Linear regression models selected both, abnormal left ventricular ejection fraction (LVEF) and abnormal myocardial perfusion, as significant indicators of an increased amygdalar activity in women (B-coefficient LVEF, - 0.096; p = 0.021; abnormal myocardial perfusion, 3.227; p = 0.043), but not in men (bone marrow p = 0.076; abnormal myocardial perfusion p = 0.420). Accordingly, an interaction term consisting of sex and LVEF/abnormal myocardial perfusion was significant (p = 0.043 and p = 0.015, respectively).

CONCLUSIONS

Upregulated amygdalar metabolism is associated with an enhanced inflammatory state in female patients with impaired cardiac function. Given that enhanced activity of the limbic system is associated with worse cardiovascular outcomes, our study suggests that a focus on inflammatory markers and indicators of distress might help to tailor cardiovascular risk assessment and therapy towards the female cardiovascular phenotype.

Gated SPECT myocardial perfusion imaging with cadmium-zinc-telluride detectors allows real-time assessment of dobutamine-stress-induced wall motion abnormalities

BACKGROUND

Left ventricular (LV) ejection fraction (EF) during high dobutamine stress (HD) by real-time gated-SPECT myocardial perfusion imaging (MPI) on a cadmium-zinc-telluride (CZT) gamma camera was validated versus cardiac magnetic resonance imaging (CMR).

METHODS AND RESULTS

After injecting 99mTc-tetrofosmin (320 MBq) in 50 patients (mean age 64 +/- 11 years), EF at rest and post-stress as well as relevant changes in EF at HD (ΔEF ≥ 5%) were assessed. CZT and CMR rest EF values yielded an excellent correlation and agreement (r = 0.96; P < 0.001; Bland-Altman limits of agreement (BA): + 0 to 14.8%). HD EF acquisition was feasible using CZT and correlated better to HD CMR EF than did post-stress CZT EF (r = 0.85 vs 0.76, respectively, all P < 0.001). Agreement in ΔEF detection between HD CMR and immediate post-stress CZT (reflecting standard acquisition using conventional SPECT camera unable to scan during stress) was 45%, while this increased to 85% with real-time HD CZT scan.

CONCLUSION

Real-time ultrafast dobutamine gated-SPECT MPI with a CZT device is feasible and provides accurate measurements of HD LV performance.

Metabolic Activity in Central Neural Structures of Patients With Myocardial Injury

Background

Increasing evidence suggests a psychosomatic link between neural systems and the heart. In light of the growing burden of ischemic cardiovascular disease across the globe, a better understanding of heart‐brain interactions and their implications for cardiovascular treatment strategies is needed. Thus, we sought to investigate the interaction between myocardial injury and metabolic alterations in central neural areas in patients with suspected or known coronary artery disease.

Methods and Results

The association between resting metabolic activity in distinct neural structures and cardiac function was analyzed in 302 patients (aged 66.8±10.2 years; 70.9% men) undergoing fluor‐18‐deoxyglucose positron emission tomography and ^99mTc‐tetrofosmin single‐photon emission computed tomography myocardial perfusion imaging. There was evidence for reduction of callosal, caudate, and brainstem fluor‐18‐deoxyglucose uptake in patients with impaired left ventricular ejection fraction (<55% versus ≥55%: P=0.047, P=0.022, and P=0.013, respectively) and/or in the presence of myocardial ischemia (versus normal perfusion: P=0.010, P=0.013, and P=0.016, respectively). In a sex‐stratified analysis, these differences were observed in men, but not in women. A first‐order interaction term consisting of sex and impaired left ventricular ejection fraction or myocardial ischemia was identified as predictor of metabolic activity in these neural regions (left ventricular ejection fraction: P=0.015 for brainstem; myocardial ischemia: P=0.004, P=0.018, and P=0.003 for callosal, caudate, or brainstem metabolism, respectively).

Conclusions

Myocardial dysfunction and injury are associated with reduced resting metabolic activity of central neural structures, including the corpus callosum, the caudate nucleus, and the brainstem. These associations differ in women and men, suggesting sex differences in the pathophysiological interplay of the nervous and cardiovascular systems.

Subclinical Atherosclerosis Imaging in People Living with HIV

In many, but not all studies, people living with HIV (PLWH) have an increased risk of coronary artery disease (CAD) events compared to the general population. This has generated considerable interest in the early, non-invasive detection of asymptomatic (subclinical) atherosclerosis in PLWH. Ultrasound studies assessing carotid artery intima-media thickness (CIMT) have tended to show a somewhat greater thickness in HIV+ compared to HIV−, likely due to an increased prevalence of cardiovascular (CV) risk factors in PLWH. Coronary artery calcification (CAC) determination by non-contrast computed tomography (CT) seems promising to predict CV events but is limited to the detection of calcified plaque. Coronary CT angiography (CCTA) detects calcified and non-calcified plaque and predicts CAD better than either CAC or CIMT. A normal CCTA predicts survival free of CV events over a very long time-span. Research imaging techniques, including black-blood magnetic resonance imaging of the vessel wall and 18F-fluorodeoxyglucose positron emission tomography for the assessment of arterial inflammation have provided insights into the prevalence of HIV-vasculopathy and associated risk factors, but their clinical applicability remains limited. Therefore, CCTA currently appears as the most promising cardiac imaging modality in PLWH for the evaluation of suspected CAD, particularly in patients <50 years, in whom most atherosclerotic coronary lesions are non-calcified.

Sex Differences in the Association between Inflammation and Ischemic Heart Disease

BACKGROUND

 Inflammation plays a fundamental role in mediating all stages of atherosclerosis. Given the higher prevalence of inflammatory rheumatologic conditions in women and the female propensity towards worse cardiovascular outcomes, refined strategies are needed to better identify the high-risk female cardiovascular phenotype.

OBJECTIVES

 This article aims to assess sex-specific links between inflammatory processes and the development and progression of ischemic heart disease.

PATIENTS AND METHODS

 The relationship between vertebral bone marrow metabolism-a marker of inflammation-and myocardial injury was retrospectively assessed in 294 patients (28.6% women, mean age: 66.9 ± 10.0 years) who underwent ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) and ^99mTc-tetrofosmin single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI).

RESULTS

 A significant increase in ¹⁸F-FDG bone marrow uptake was observed in women with impaired myocardial perfusion (SPECT-MPI) as compared to women with normal myocardial perfusion (standardized uptake value [SUV]: 2.2 ± 1.2 vs. 1.7 ± 0.5, p = 0.013), while no such difference was observed in men (SUV: 1.6 ± 0.8 vs. 1.6 ± 0.4, p = 0.372). Furthermore, a significant inverse correlation between left ventricular ejection fraction (LVEF) and bone marrow metabolism was seen in women (r = -0.229, p = 0.037), but not in men (r = -0.075, p = 0.289). Accordingly, in women, but not in men, bone marrow activity was identified as an independent predictor of both, reduced LVEF (β-coefficient, -4.537; p = 0.040) and impaired myocardial perfusion (β-coefficient, 0.138; p = 0.014).

CONCLUSION

 A strong link between bone marrow metabolism and impaired myocardial function and perfusion was observed in women, but not in men. Our data suggest that novel biomarkers of inflammation might help to identify women at risk for ischemic cardiomyopathy and to tailor disease management to the female cardiovascular phenotype.

Diagnosis of obstructive coronary artery disease using computed tomography angiography in patients with stable chest pain depending on clinical probability and in clinically important subgroups: meta-analysis of individual patient data

OBJECTIVE

To determine whether coronary computed tomography angiography (CTA) should be performed in patients with any clinical probability of coronary artery disease (CAD), and whether the diagnostic performance differs between subgroups of patients.

DESIGN

Prospectively designed meta-analysis of individual patient data from prospective diagnostic accuracy studies.

DATA SOURCES

Medline, Embase, and Web of Science for published studies. Unpublished studies were identified via direct contact with participating investigators.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Prospective diagnostic accuracy studies that compared coronary CTA with coronary angiography as the reference standard, using at least a 50% diameter reduction as a cutoff value for obstructive CAD. All patients needed to have a clinical indication for coronary angiography due to suspected CAD, and both tests had to be performed in all patients. Results had to be provided using 2×2 or 3×2 cross tabulations for the comparison of CTA with coronary angiography. Primary outcomes were the positive and negative predictive values of CTA as a function of clinical pretest probability of obstructive CAD, analysed by a generalised linear mixed model; calculations were performed including and excluding non-diagnostic CTA results. The no-treat/treat threshold model was used to determine the range of appropriate pretest probabilities for CTA. The threshold model was based on obtained post-test probabilities of less than 15% in case of negative CTA and above 50% in case of positive CTA. Sex, angina pectoris type, age, and number of computed tomography detector rows were used as clinical variables to analyse the diagnostic performance in relevant subgroups.

RESULTS

Individual patient data from 5332 patients from 65 prospective diagnostic accuracy studies were retrieved. For a pretest probability range of 7-67%, the treat threshold of more than 50% and the no-treat threshold of less than 15% post-test probability were obtained using CTA. At a pretest probability of 7%, the positive predictive value of CTA was 50.9% (95% confidence interval 43.3% to 57.7%) and the negative predictive value of CTA was 97.8% (96.4% to 98.7%); corresponding values at a pretest probability of 67% were 82.7% (78.3% to 86.2%) and 85.0% (80.2% to 88.9%), respectively. The overall sensitivity of CTA was 95.2% (92.6% to 96.9%) and the specificity was 79.2% (74.9% to 82.9%). CTA using more than 64 detector rows was associated with a higher empirical sensitivity than CTA using up to 64 rows (93.4% v 86.5%, P=0.002) and specificity (84.4% v 72.6%, P<0.001). The area under the receiver-operating-characteristic curve for CTA was 0.897 (0.889 to 0.906), and the diagnostic performance of CTA was slightly lower in women than in with men (area under the curve 0.874 (0.858 to 0.890) v 0.907 (0.897 to 0.916), P<0.001). The diagnostic performance of CTA was slightly lower in patients older than 75 (0.864 (0.834 to 0.894), P=0.018 v all other age groups) and was not significantly influenced by angina pectoris type (typical angina 0.895 (0.873 to 0.917), atypical angina 0.898 (0.884 to 0.913), non-anginal chest pain 0.884 (0.870 to 0.899), other chest discomfort 0.915 (0.897 to 0.934)).

CONCLUSIONS

In a no-treat/treat threshold model, the diagnosis of obstructive CAD using coronary CTA in patients with stable chest pain was most accurate when the clinical pretest probability was between 7% and 67%. Performance of CTA was not influenced by the angina pectoris type and was slightly higher in men and lower in older patients.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42012002780.

High efficiency gamma camera enables ultra-low fixed dose stress/rest myocardial perfusion imaging

Aims

We validated a 1-day myocardial perfusion imaging (MPI) protocol using an ultra low-dose(ULD) equal for stress and rest on a cadmium zinc telluride (CZT).

Methods and results

Fifty-six patients underwent a 1-day MPI protocol using a standard (SD) 99mTc-tetrofosmin dose at stress (320 MBq) and rest (960 MBq) with 5 min acquisition time each (SD). Within 2 weeks MPI was repeated using ULD 99mTc-tetrofosmin equal for stress and rest (160 MBq) with 15 min acquisition time each (ULD). All scans were performed on a CZT camera (DNM 570c, GE Healthcare). Background subtraction was applied on the rest MPI of the ULD using P-mod software. Presence and extent of perfusion defect were analysed. Pearson's correlation was used to compare ejection fraction (EF), end diastolic volume (EDV), and end systolic volume (ESV) between both protocols. SD revealed ischaemia in 23, scar in 3, and an equivocal finding in 1 patient, while normal findings were documented in 29 patients. ULD resulted in the following findings: ischaemia 23, scar 3, and 30 normal scans. Congruence of SD and ULD was 22/23 for ischaemia, 3/3 for scar, and 29/29 in normal patients; one patient with ischaemia in SD was classified as scar in ULD. Overall agreement of ULD with SD was 98%. The mean extent of defect was comparable between SD and ULD for the stress (10% vs. 11%, respectively, P = NS) and rest studies (5% vs. 7%, respectively, P = NS). An excellent correlation between SD and ULD was found for EF (r = 0.93), EDV (r = 0.95), and ESV (r = 0.97).

Conclusion

CZT cameras may enable reliable MPI scanning in patients with known or suspected coronary artery disease using protocols with about a factor 4-decrease in radiation dose exposure compared with traditional protocols.

Ultra-low-dose coronary artery calcium scoring using novel scoring thresholds for low tube voltage protocols-a pilot study

Aims

To determine if tube-adapted thresholds for coronary artery calcium (CAC) scoring by computed tomography at 80 kilovolt-peak (kVp) tube voltage and 70-kVp yield comparable results to the standard 120-kVp protocol.

Methods and results

We prospectively included 103 patients who underwent standard scanning with 120-kVp tube voltage and additional scans with 80 kVp and 70 kVp. Mean body mass index (BMI) was 27.9 ± 5.1 kg/m2. For the lowered tube voltages, we applied novel kVp-adapted thresholds for calculation of CAC scores and compared them with standard 120-kVp scans using intraclass correlation and Bland-Altman (BA) analysis. Furthermore, risk-class (CAC score 0/1-10/11-100/101-400/>400) changes were assessed. Median CAC score from 120-kVp scans was 212 (interquartile range 25-901). Thirteen (12.6%) patients had zero CAC. Using the novel kVp-adapted thresholds, CAC scores derived from 80-kVp scans showed excellent correlation (r = 0.994, P < 0.001) with standard 120-kVp scans with BA limits of agreement of -235 (-39.5%) to 172 (28.9%). Similarly, for 70-kVp scans, correlation was excellent (r = 0.972, P < 0.001) but with broader limits of agreement of -476 (-85.0%) to 270 (48.2%). Only 2 (2.8%) reclassifications were observed for the 80-kVp scans in patients with a BMI <30 kg/m2 (n = 71), and 2 (6.1%) for the 70-kVp scans in patients with a BMI <25 kg/m2 (n = 33). Mean effective radiation dose was 0.60 ± 0.07 millisieverts (mSv), 0.19 ± 0.02 mSv, and 0.12 ± 0.01 mSv for the 120-kVp, 80-kVp, and 70-kVp scans, respectively.

Conclusion

The present study suggests that CAC scoring with reduced peak tube voltage is accurate if kVp-adapted thresholds for calculation of CAC scores are applied while offering a substantial further radiation dose reduction.

Diagnosis and Management of Anomalous Coronary Arteries with a Malignant Course

Although the prevalence of anomalous coronary artery from the opposite sinus (ACAOS) in the general population is low, more frequent use of invasive and non-invasive imaging to rule out coronary artery disease has seen an increase in absolute numbers of ACAOS. ACAOS are traditionally classified as malignant (with an interarterial course) and benign variants. Malignant variants have been recognised in autopsy studies to be an underlying cause of sudden cardiac death in young athletes. Conversely, it seems that older people with ACAOS are less predisposed to adverse cardiac events. Non-invasive anatomic imaging is complementary to invasive imaging and helps to further identify high-risk anatomic features. Using functional non-invasive perfusion imaging can assess potential ischaemia induced by dynamic compression of malignant ACAOS. Information gained from clinical imaging guides the management of these patients.

Quantification of intrathoracic fat adds prognostic value in women undergoing myocardial perfusion imaging

AIM

Amongst patients with coronary artery disease (CAD), women experience relatively worse outcomes as compared to men. Evidence to date has failed to explore unique female imaging targets as major determinants of cardiovascular risk. We sought to assess the prognostic value of epicardial (EFV) and intrathoracic fat volume (IFV) quantification in women and men with suspected and known CAD.

METHODS AND RESULTS

Intrathoracic fat volume and EFV were calculated from non-contrast CT and analyzed in a propensity-matched cohort of 190 patients (95 women, mean age 62.5 ± 11.3 years) undergoing myocardial perfusion imaging (MPI) and coronary computed tomography angiography (CCTA) for evaluation of CAD. IFV and EFV were significantly lower in women as compared to men (198.2 ± 78.4 vs 293.2 ± 114.7 cm³ and 105.6 ± 48.9 vs 135.8 ± 60.9 cm³, p < 0.001) and showed a strong association with coronary artery calcium score (CACS) and obstructive CAD in women (p < 0.05), but not in men. Fat volumes were not related to abnormal MPI in either population (p = NS). During a median follow-up of 2.8 years, high IFV was associated with reduced event free survival (log rank = 0.019 vs low IFV) in women, but not in men. Accordingly, a multivariate Cox regression model adjusted for cardiovascular risk factors, CACS, CCTA, and MPI findings selected IFV as a significant predictor of major adverse cardiovascular events (MACE) in women (HR 1.32, 95%CI 1.18-1.55, p = 0.001).

CONCLUSION

Quantification of IFV provides incremental prognostic value for MACE in women, beyond that provided by traditional risk factors and imaging findings.

Corrected coronary opacification decrease from coronary computed tomography angiography: Validation with quantitative 13N-ammonia positron emission tomography

BACKGROUND

To assess the functional relevance of a coronary artery stenosis, corrected coronary opacification (CCO) decrease derived from coronary computed tomography angiography (CCTA) has been proposed. The present study aims at validating CCO decrease with quantitative 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI).

METHODS AND RESULTS

This retrospective study consists of 39 patients who underwent hybrid CCTA/PET-MPI. From CCTA, attenuation in the coronary lumen was measured before and after a stenosis and corrected to the aorta to calculate CCO and its decrease. Relative flow reserve (RFR) was calculated by dividing the stress myocardial blood flow (MBF) of a vessel territory subtended by a stenotic coronary by the stress MBF of the reference territories without stenoses. RFR was abnormal in 11 vessel territories (27%). CCO decrease yielded a sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for prediction of an abnormal RFR of 73%, 70%, 88%, 47%, and 70%, respectively.

CONCLUSIONS

CCTA-derived CCO decrease has moderate diagnostic accuracy to predict an abnormal RFR in PET-MPI. However, its high negative predictive value to rule out functional relevance of a given lesion may confer clinical implications in the diagnostic work-up of patients with a coronary stenosis.

Imaging the event-prone coronary artery plaque

Acute coronary events, the dreaded manifestation of coronary atherosclerosis, remain one of the main contributors to mortality and disability in the developed world. The majority of those events are associated with atherosclerotic plaques-related thrombus formation following an acute disruption, that being rupture or erosion, of an event-prone lesion. These historically termed vulnerable plaques have been the target of numerous benchtop and clinical research endeavors, yet to date without solid results that would allow for early identification and potential treatment. Technological leaps in cardiovascular imaging have provided novel insights into the formation and role of the event-prone plaques. From intracoronary optical coherence tomography that has enhanced our understanding of the pathophysiological mechanisms of plaque disruption, over coronary computed tomography angiography that enables non-invasive serial plaque imaging, and positron emission tomography poised to be rapidly implemented into clinical practice to the budding field of plaque imaging with cardiac magnetic resonance, we summarize the invasive and non-invasive imaging modalities currently available in our armamentarium. Finally, the current status and potential future imaging directions are critically appraised.

Association between beta-adrenoceptor antagonist-induced sympathicolysis and severity of coronary artery disease as assessed by coronary computed tomography angiography (CCTA)

Enhanced sympathetic nervous system activity is associated with increased mortality in many cardiac conditions including heart failure and coronary artery disease (CAD). To ensure adequate image quality of coronary CT angiography (CCTA), pre-scan β-adrenergic blockers (BB) are routinely administered. It is currently unknown whether sensitivity to sympathicolytic compounds is associated with severity of CAD. A total of 2633 consecutive patients (1733 [65.8%] men and 900 [34.2%] women, mean age 56.7 ± 11.5 years) undergoing CCTA for exclusion of significant CAD at our department between 06/2013 and 12/2016 were evaluated. Acute heart rate (HR) responses to BB administration were recorded in all patients. Coronary plaque burden as indicated by segment severity score (SSS), segment involvement score (SIS), and significant CAD (i.e. > 50% luminal narrowing) was higher in weak responders to BB as compared to strong responders to BB (p = 0.001 for SSS and SIS, and p = 0.021 for significant CAD). Accordingly, in a multiple linear regression model adjusted for known risk factors of CAD such as smoking, hypertension, diabetes and dyslipidaemia, as well as age, sex, body mass index (BMI), glomerular filtration rate, and HR during CCTA scan, a strong response to BB was selected as a significant independent negative predictor of coronary plaque burden (beta coefficient - 0.08, p = 0.001). We demonstrate that individuals with a weak acute response to BB administration encounter an increased risk of severe CAD. Taking into account sensitivity to sympatho-inhibition may add complementary information in patients undergoing CCTA for evaluation of CAD.

Head-to-head comparison of adaptive statistical and model-based iterative reconstruction algorithms for submillisievert coronary CT angiography

Aims

Iterative reconstruction (IR) algorithms allow for a significant reduction in radiation dose of coronary computed tomography angiography (CCTA). We performed a head-to-head comparison of adaptive statistical IR (ASiR) and model-based IR (MBIR) algorithms to assess their impact on quantitative image parameters and diagnostic accuracy for submillisievert CCTA.

Methods and results

CCTA datasets of 91 patients were reconstructed using filtered back projection (FBP), increasing contributions of ASiR (20, 40, 60, 80, and 100%), and MBIR. Signal and noise were measured in the aortic root to calculate signal-to-noise ratio (SNR). In a subgroup of 36 patients, diagnostic accuracy of ASiR 40%, ASiR 100%, and MBIR for diagnosis of coronary artery disease (CAD) was compared with invasive coronary angiography. Median radiation dose was 0.21 mSv for CCTA. While increasing levels of ASiR gradually reduced image noise compared with FBP (up to - 48%, P < 0.001), MBIR provided largest noise reduction (-79% compared with FBP) outperforming ASiR (-59% compared with ASiR 100%; P < 0.001). Increased noise and lower SNR with ASiR 40% and ASiR 100% resulted in substantially lower diagnostic accuracy to detect CAD as diagnosed by invasive coronary angiography compared with MBIR: sensitivity and specificity were 100 and 37%, 100 and 57%, and 100 and 74% for ASiR 40%, ASiR 100%, and MBIR, respectively.

Conclusion

MBIR offers substantial noise reduction with increased SNR, paving the way for implementation of submillisievert CCTA protocols in clinical routine. In contrast, inferior noise reduction by ASiR negatively affects diagnostic accuracy of submillisievert CCTA for CAD detection.