Radiation exposure and coronary artery calcium scans in the society for heart attack prevention and eradication cohort

Feasibility analysis of non-electrocardiogram-triggered chest low-dose computed tomography using a kV-independent reconstruction algorithm for predicting cardiovascular disease risk in patients receiving maintenance hemodialysis

OBJECTIVES

This study aimed to evaluate the feasibility and accuracy of non-electrocardiogram (ECG)-triggered chest low-dose computed tomography (LDCT) with a kV-independent reconstruction algorithm in assessing coronary artery calcification (CAC) degree and cardiovascular disease risk in patients receiving maintenance hemodialysis (MHD).

METHODS

In total, 181 patients receiving MHD who needed chest CT and coronary artery calcium score (CACS) scannings sequentially underwent non-ECG-triggered, automated tube voltage selection, high-pitch chest LDCT with a kV-independent reconstruction algorithm and ECG-triggered standard CACS scannings. Then, the image quality, radiation doses, Agatston scores (ASs), and cardiac risk classifications of the two scans were compared.

RESULTS

Of the 181 patients, 89, 83, and 9 were scanned at 100, 110, and 120 kV, respectively. Excluding those scanned at 120 kV, 172 patients were enrolled. Although the ASs of non-ECG-triggered LDCT were lower than those of the standard CACS, the agreement and correlation of ASs of the two scans were excellent, and both intraclass correlation coefficients (ICCs) and Pearson's correlation coefficients were > 0.96. Cardiac risk classifications did not significantly differ between the non-ECG-triggered LDCT and standard CACS (χ2 = 3.933, P = 0.269), and the agreement was excellent (weighted kappa value = 0.936; 95% confidence interval (CI): 0.903-0.970). The effective radiation doses of standard CACS and non-ECG-triggered chest LDCT scannings were 1.34 ± 0.74 and 1.04 ± 0.35 mSv, respectively.

CONCLUSIONS

The non-ECG-triggered, automated tube voltage selection, high-pitch chest LDCT protocol with a kV-independent reconstruction algorithm can obtain chest scans and ASs simultaneously and significantly reduce patients' radiation exposure.

3D Landmark scout imaging accurately assesses presence and extent of coronary calcification with lower radiation exposure

BACKGROUND

Cardiac CT for coronary artery calcium (CAC) scoring exposes patients to 1 ​mSv of radiation. A new CT scout method utilizing ultra-low dose CT (3D Landmark) offers tomographic cross-sectional imaging, which provides axial images from which CAC can be estimated. The purpose of our study is to analyze the association between estimated CAC burden on 3D Landmark scout imaging vs dedicated ECG-gated CACS.

METHODS

Consecutive patients over a 9-month period undergoing non-contrast ECG-gated CACS planned with 3D Landmark scout imaging were included. Extent of CAC on 3D Landmark scout imaging was scored from 0 to 3 (none, mild, moderate, severe). Agatston CACS was converted to an ordinal score from 0 to 3, corresponding to absent (0), mild (1-99), moderate (100-400), or severe (>400). Fischer's exact test, weighted kappa coefficient, and paired t-tests were used for analysis.

RESULTS

Of 150 patients, 51.3% were female with mean age 49.0 ​± ​16.8 and BMI 28.6 ​± ​12.3. Sensitivity of 3D Landmark in identifying calcium was 96.2%, with specificity of 100%. There was strong interrater agreement between 3D Landmark calcium scoring and CACS, with weighted kappa coefficient 0.97 ​± ​0.01(CI 0.95-0.99). Radiation dose-length-product was significantly lower for 3D Landmark imaging vs. dedicated ECG-gated CACS (9.7 ​± ​3.6 vs 43.8 ​± ​26.4 ​mGy ​cm, p ​< ​0.001) despite longer scan length (465.0 ​± ​160.8 vs 123.0 ​± ​12.7 ​mm, respectively).

CONCLUSION

Estimated coronary artery calcium on 3D Landmark scout images correlates strongly with Agatston CACS, demonstrating utility in assessing cardiovascular risk without introducing additional radiation or costs.

Coronary and Extra-coronary Subclinical Atherosclerosis to Guide Lipid-Lowering Therapy

PURPOSE OF REVIEW

To discuss and review the technical considerations, fundamentals, and guideline-based indications for coronary artery calcium scoring, and the use of other non-invasive imaging modalities, such as extra-coronary calcification in cardiovascular risk prediction.

RECENT FINDINGS

The most robust evidence for the use of CAC scoring is in select individuals, 40-75 years of age, at borderline to intermediate 10-year ASCVD risk. Recent US recommendations support the use of CAC scoring in varying clinical scenarios. First, in adults with very high CAC scores (CAC ≥ 1000), the use of high-intensity statin therapy and, if necessary, guideline-based add-on LDL-C lowering therapies (ezetimibe, PCSK9-inhibitors) to achieve a ≥ 50% reduction in LDL-C and optimally an LDL-C < 70 mg/dL is recommended. In patients with a CAC score ≥ 100 at low risk of bleeding, the benefits of aspirin use may outweigh the risk of bleeding. Other applications of CAC scoring include risk estimation on non-contrast CT scans of the chest, risk prediction in younger patients (< 40 years of age), its value as a gatekeeper for the decision to perform nuclear stress testing, and to aid in risk stratification in patients presenting with low-risk chest pain. There is a correlation between extra-coronary calcification (e.g., breast arterial calcification, aortic calcification, and aortic valve calcification) and incident ASCVD events. However, its role in informing lipid management remains unclear. Identification of coronary calcium in selected patients is the single best non-invasive imaging modality to identify future ASCVD risk and inform lipid-lowering therapy decision-making.

Atherosclerotic Cardiovascular Disease in Women: Providing Protection With Lipid-altering Agents

PURPOSE

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death in women, yet it remains underdiagnosed, undertreated, and understudied in women compared with men. Although estrogen has provided observational evidence of cardioprotection, randomized controlled trials using hormone replacement therapy have generally produced unfavorable results.

METHODS

For this narrative review, a literature search was performed using the key words cardiovascular disease, women, and dyslipidemia in PubMed and Google Scholar with no date limitations. References within each article were also reviewed for additional relevant articles.

FINDINGS

Sex-specific risk factors and underrecognized conditions more predominant in women elevate ASCVD risk, creating further clinical challenges, such as the need for accurate risk stratification, compared with in men. Dyslipidemia frequently manifests or worsens during the menopausal transition. Therefore, identification during midlife and implementing lipid-lowering strategies to reduce ASCVD risk is imperative. Women have historically been poorly represented in cardiovascular (CV) outcome trials. However, more recent studies and meta-analyses have indicated that lipid-lowering therapies are equally effective in women and produce similar reductions in CV events and total mortality. Major cholesterol guidelines address many of the challenges that clinicians face when assessing ASCVD risk in women. Key points specific to women include obtaining a detailed history of pregnancy-related conditions, identification of common autoimmune disorders associated with systemic inflammation, and use of 10-year ASCVD risk calculators and imaging modalities (coronary artery calcium) to optimize ASCVD assessment. In terms of treatment, similar to men, women with existing ASCVD or high-risk primary prevention patients should be treated aggressively to achieve ≥50% LDL-C reductions and/or LDL-C goals as low as <55 mg/dL. Appropriate lipid-lowering therapies include high-intensity statins with or without ezetimibe and proprotein convertase subtilisin kexin/type 9 inhibitors. Women with lower ASCVD risk may be considered for low- to moderate-intensity statin therapy (approximately 30%-50% LDL-C reduction). All women, regardless of ASCVD risk category, should implement therapeutic lifestyle changes, which improve many common age-related cardiometabolic conditions.

IMPLICATIONS

Although ASCVD and current risk factor trends in women are concerning, numerous evidence-based approaches are available to protect women with ASCVD risk from life-changing CV events.

Debates in cardiac CT: Coronary CT angiography is the best test in asymptomatic patients

Cardiovascular disease remains a major cause of mortality, accounting for a third of all global deaths annually. Although there have been major improvements in our ability to detect and to treat patients with coronary heart disease, most myocardial infarctions occur in previously asymptomatic individuals. Identification of individuals at risk of myocardial infarction remains challenging and primary prevention guidelines rely on the use of cardiovascular risk scores that can be supplemented by coronary artery calcium scores. Coronary artery calcium scores provide a simple surrogate late marker of atherosclerosis but is unable to identify the early high risk non-calcified plaque which can be particularly problematic in younger individuals. Coronary computed tomography angiography is increasingly being used as the imaging strategy of choice in patients with symptoms of coronary heart disease. As an anatomical test, it can non-invasively detect the presence of coronary atherosclerosis, providing clinicians with a strong mandate to commence symptom relieving and preventative therapies. For asymptomatic individuals, it allows precise targeting of therapies to those with coronary heart disease rather than those "at risk" of disease. Moreover, our ability to calculate risk using coronary computed tomography angiography is rapidly improving with the use of techniques, such as plaque quantification and characterisation. These techniques have the potential to provide clinicians with tools to target cardiovascular disease prevention in a precision medicine approach. We here debate the ways in which coronary computed tomography angiography could improve the selection of asymptomatic individuals for preventative therapies over and above risk calculators and calcium scoring.

The Role of Cardiac Computed Tomography in Heart Failure

PURPOSE OF REVIEW

Cardiac computed tomography (CT) is becoming a more widely applied tool in the diagnosis and management of a variety of cardiovascular conditions, including heart failure. The aim of this narrative review is to examine the role of cardiac CT in patients with heart failure.

RECENT FINDINGS

Coronary computed tomographic angiography has robust diagnostic accuracy for ruling out coronary artery disease. These data are reflected in updated guidelines from major cardiology organizations. New roles for cardiac CT in myocardial imaging, perfusion scanning, and periprocedural planning, execution, and monitoring are being implemented. Cardiac CT is useful in ruling out coronary artery disease its diagnostic accuracy, accessibility, and safety. It is also intricately linked to invasive cardiac procedures that patients with heart failure routinely undergo.

Coronary Artery Calcium Versus Pooled Cohort Equations Score for Primary Prevention Guidance: Randomized Feasibility Trial

OBJECTIVES

This study sought to determine the feasibility of performing an extensive randomized outcomes trial comparing a coronary artery calcium (CAC)- versus a pooled cohort equations (PCE) risk score-based strategy for initiating statin therapy for primary atherosclerotic cardiovascular disease (ASCVD) prevention.

BACKGROUND

Statin therapy is standard for the primary prevention of ASCVD in subjects at increased risk. National guidelines recommend using the American College of Cardiology/American Heart Association PCE risk score to guide a statin recommendation. Whether guidance by a CAC score is equivalent or superior is unknown.

METHODS

CorCal (Effectiveness of a Proactive Cardiovascular Primary Prevention Strategy, With or Without the Use of Coronary Calcium Screening, in Preventing Future Major Adverse Cardiac Events) was a randomized trial consenting 601 patients without known ASCVD, diabetes, or prior statin therapy recruited from primary care clinics and randomized to CAC- (n = 302) or PCE guidance (n = 299) of statin initiation for primary prevention. Enrolled subjects and their physicians made final treatment decisions. Primary outcomes compared the proportion of statin recommendations received and subject adherence over 1 year between CAC- and PCE-arm subjects. Modeled medical costs, adverse effects, and low-density lipoprotein-cholesterol (LDL-C) were additional measures of interest.

RESULTS

Subjects were well matched, and 540 (89.9%) completed entry testing and received a protocol-based recommendation. A statin was recommended in 101 (35.9%) CAC- and 124 (47.9%) PCE-arm subjects (P = 0.005). Compared to PCE-based recommendations, CAC-arm subjects were reclassified from statin to no statin in 36.0% and from no statin to statin in 5.6% of cases, resulting in a total reclassification of 20.6%. Physicians accepted the study-dictated recommendation to start a statin in 88.1% of CAC- vs 75.0% of PCE-arm subjects (P = 0.01). Patient-reported adherence to this recommendation at 3 months was 62.2% vs 42.2%, respectively (P = 0.009). At 1 year, statin adherence remained superior, LDL-C levels were lower, estimated costs were similar or reduced in CAC subjects, and few events occurred.

CONCLUSIONS

CAC guidance may be a more efficient, personalized, cost-effective, and motivating approach to statin initiation and maintenance in primary prevention. This feasibility phase of CorCal should be regarded as hypothesis-generating with respect to cardiovascular outcomes, which is being addressed in a large, longer-term outcomes trial. (Effectiveness of a Proactive Cardiovascular Primary Prevention Strategy, With or Without the Use of Coronary Calcium Screening, in Preventing Future Major Adverse Cardiac Events [CorCal]; NCT03439267).

Subclinical cardiovascular disease and utility of coronary artery calcium score

ASCVD are the leading causes of mortality and morbidity among Globe. Evaluation of patients' comprehensive and personalized risk provides risk management strategies and preventive interventions to achieve gain for patients. Framingham Risk Score (FRS) and Systemic Coronary Risk Evaluation Score (SCORE) are two well studied risk scoring models, however, can miss some (20-35%) of future cardiovascular events. To obtain more accurate risk assessment recalibrating risk models through utilizing novel risk markers have been studied in last 3 decades and both ESC and AHA recommends assessing Family History, hs-CRP, CACS, ABI, and CIMT. Subclinical Cardiovascular Disease (SCVD) has been conceptually developed for investigating gradually progressing asymptomatic development of atherosclerosis and among these novel risk markers it has been well established by literature that CACS having highest improvement in risk assessment. This review study mainly selectively discussing studies with CACS measurement. A CACS = 0 can down-stratify risk of patients otherwise treated or treatment eligible before test and can reduce unnecessary interventions and cost, whereas CACS ≥ 100 is equivalent to statin treatment threshold of ≥ 7.5% risk level otherwise statin ineligible before test. Since inflammation, insulin resistance, oxidative stress, dyslipidemia and ongoing endothelial damage due to hypertension could lead to CAC, ASCVD linked with comorbidities. Recent cohort studies have shown a CACS 100-300 as a sign of increased cancer risk. Physical activity, dietary factors, cigarette use, alcohol consumption, metabolic health, family history of CHD, aging, exposures of neighborhood environment and non-cardiovascular comorbidities can determine CACs changes.

Cardiac Computed Tomography in Cardio-Oncology: JACC: CardioOncology Primer

Cancer patients and survivors have elevated cardiovascular risk when compared with noncancer patients. Cardio-oncology has emerged as a new subspecialty to comanage and address cardiovascular complications in cancer patients such as heart failure, atherosclerotic cardiovascular disease (ASCVD), valvular heart disease, pericardial disease, and arrhythmias. Cardiac computed tomography (CT) can be helpful in identifying both clinical and subclinical ASCVD in cancer patients and survivors. Radiation therapy treatment planning CT scans and cancer staging/re-staging imaging studies can quantify calcium scores which can identify pre-existing subclinical ASCVD. Cardiac CT can be helpful in the evaluation of cardiac tumors and pericardial diseases, especially in patients who cannot tolerate or have a contraindication to cardiac magnetic resonance. In this review, we describe the optimal utilization of cardiac CT in cancer patients, including risk assessment for ASCVD and identification of cancer treatment-related cardiovascular toxicity.

Assessment of Coronary Artery Calcium Scoring to Guide Statin Therapy Allocation According to Risk-Enhancing Factors: The Multi-Ethnic Study of Atherosclerosis

Importance

The 2018 American Heart Association/American College of Cardiology Guideline on the Management of Blood Cholesterol recommends the use of risk-enhancing factor assessment and the selective use of coronary artery calcium (CAC) scoring to guide the allocation of statin therapy among individuals with an intermediate risk of atherosclerotic cardiovascular disease (ASCVD).

Objective

To examine the association between risk-enhancing factors and incident ASCVD by CAC burden among those at intermediate risk of ASCVD.

Design, Setting, and Participants

The Multi-Ethnic Study of Atherosclerosis is a multicenter population-based prospective cross-sectional study conducted in the US. Baseline data for the present study were collected between July 15, 2000, and July 14, 2002, and follow-up for incident ASCVD events was ascertained through August 20, 2015. Participants were aged 45 to 75 years with no clinical ASCVD or diabetes at baseline, were at intermediate risk of ASCVD (≥7.5% to <20.0%), and had a low-density lipoprotein cholesterol level of 70 to 189 mg/dL.

Exposures

Family history of premature ASCVD, premature menopause, metabolic syndrome, chronic kidney disease, lipid and inflammatory biomarkers, and low ankle-brachial index.

Main Outcomes and Measures

Incident ASCVD over a median follow-up of 12.0 years.

Results

A total of 1688 participants (mean [SD] age, 65 [6] years; 976 men [57.8%]). Of those, 648 individuals (38.4%) were White, 562 (33.3%) were Black, 305 (18.1%) were Hispanic, and 173 (10.2%) were Chinese American. A total of 722 participants (42.8%) had a CAC score of 0. Among those with 1 to 2 risk-enhancing factors vs those with 3 or more risk-enhancing factors, the prevalence of a CAC score of 0 was 45.7% vs 40.3%, respectively. Over a median follow-up of 12.0 years (interquartile range [IQR], 11.5-12.6 years), the unadjusted incidence rate of ASCVD among those with a CAC score of 0 was less than 7.5 events per 1000 person-years for all individual risk-enhancing factors (with the exception of ankle-brachial index, for which the incidence rate was 10.4 events per 1000 person-years [95% CI, 1.5-73.5]) and combinations of risk-enhancing factors, including participants with 3 or more risk-enhancing factors. Although the individual and composite addition of risk-enhancing factors to the traditional risk factors was associated with improvement in the area under the receiver operating curve, the use of CAC scoring was associated with the greatest improvement in the C statistic (0.633 vs 0.678) for ASCVD events. For incident ASCVD, the net reclassification improvement for CAC was 0.067.

Conclusions and Relevance

In this cross-sectional study, among participants with CAC scores of 0, the presence of risk-enhancing factors was generally not associated with an overall ASCVD risk that was higher than the recommended treatment threshold for the initiation of statin therapy. The use of CAC scoring was associated with significant improvements in the reclassification and discrimination of incident ASCVD. The results of this study support the utility of CAC scoring as an adjunct to risk-enhancing factor assessment to more accurately classify individuals with an intermediate risk of ASCVD who might benefit from statin therapy.

Coronary Artery Disease in Patients with HIV Infection: An Update

Premature cardiovascular disease among the HIV-infected population is of great concern among clinicians. The increased life expectancy of HIV-infected individuals is mainly due to the early detection of infection and the advent of antiretroviral therapy. Once known as a deadly disease, HIV infection has transitioned into a chronic condition. Cardiovascular disease in this population is thought to progress early due to traditional and non-traditional risk factors. Early detection of subclinical atherosclerosis has become a center of focus in research as our complete understanding of this process it not yet well known. Advancements in cardiac computed tomography angiography has enabled the exploration of coronary artery disease by further evaluation of coronary stenosis and plaque analysis. An increase in cardiovascular event rates in this population is currently thought to be linked to antiretroviral therapy, Framingham risk factors, and HIV. We sought to present an updated comprehensive review of the available literature on HIV related to atherosclerosis and cardiovascular risk.

The National Lipid Association scientific statement on coronary artery calcium scoring to guide preventive strategies for ASCVD risk reduction

An Expert Panel of the National Lipid Association reviewed the evidence related to the use of coronary artery calcium (CAC) scoring in clinical practice for adults seen for primary prevention of atherosclerotic cardiovascular disease. Recommendations for optimal use of this test in adults of various races/ethnicities, ages and multiple domains of primary prevention, including those with a 10-year ASCVD risk <20%, those with diabetes or the metabolic syndrome, and those with severe hypercholesterolemia were provided. Recommendations were also made on optimal timing for repeat calcium scoring after an initial test, use of CAC scoring in those taking statins, and its role in informing the clinician patient discussion on the benefit of aspirin and anti-hypertensive drug therapy. Finally, a vision is provided for the future of coronary calcium scoring.

Conventional Computed Tomographic Calcium Scoring vs full chest CTCS for lung cancer screening: a cost-effectiveness analysis

Background

Conventional CTCS images the mid/lower chest for coronary artery disease (CAD). Because many CAD patients are also at risk for lung malignancy, CTCS often discovers incidental pulmonary nodules (IPN). CTCS excludes the upper chest, where malignancy is common. Full-chest CTCS (FCT) may be a cost-effective screening tool for IPN.

Methods

A decision tree was created to compare a FCT to CTCS in a hypothetical patient cohort with suspected CAD. (Figure) The design compares the effects of missed cancers on CTCS with the cost of working up non-malignant nodules on FCT. The model was informed by results of the National Lung Screening Trial and literature review, including the rate of malignancy among patients receiving CTCS and the rate of malignancy in upper vs lower portions of the lung. The analysis outcomes are Quality-Adjusted Life Year (QALY) and incremental cost-effectiveness ratio (ICER), which is generally considered beneficial when <$50,000/QALY.

Results

Literature review suggests that rate of IPNs in the upper portion of the lung varied from 47 to 76%. Our model assumed that IPNs occur in upper and lower portions of the lung with equal frequency. The model also assumes an equal malignancy potential in upper lung IPNs despite data that malignancy occurs 61–66% in upper lung fields.

In the base case analysis, a FCT will lead to an increase of 0.03 QALYs comparing to conventional CTCS (14.54 vs 14.51 QALY, respectively), which translates into an QALY increase of 16 days. The associated incremental cost for FCT is $278 ($1027 vs $748, FCT vs CTCS respectively. The incremental cost-effectiveness ratio (ICER) is $10,289/QALY, suggesting significant benefit. Sensitivity analysis shows this benefit increases proportional to the rate of malignancy in upper lung fields.

Conclusion

Conventional CTCS may be a missed opportunity to screen for upper lung field cancers in high risk patients. The ICER of FCT is better than screening for breast cancer screening (mammograms $80 k/QALY) and colon cancer (colonoscopy $6 k/QALY). Prospective studies are appropriate to define protocols for FCT.

Individualized coronary calcium scoring at any tube voltage using a kV-independent reconstruction algorithm

PURPOSE

We prospectively investigate the feasibility of a patient specific automated tube voltage selection (ATVS)-based coronary artery calcium scoring (CACS) protocol, using a kV-independent reconstruction algorithm, to achieve significant dose reductions while maintaining the overall cardiac risk classification.

METHODS

Forty-three patients (mean age, 61.8 ± 9.0 years; 40% male) underwent a clinically indicated CACS scan at 120kVp, as well as an additional CACS acquisition using an individualized tube voltage between 70 and 130kVp based on the ATVS selection (CARE-kV). Datasets of the additional CACS scans were reconstructed using a kV-independent algorithm that allows for calcium scoring without changing the weighting threshold of 130HU, regardless of the tube voltage chosen for image acquisition. Agatston scores and radiation dose derived from the different ATVS-based CACS studies were compared to the standard acquisition at 120kVp.

RESULTS

Thirteen patients displayed a score of 0 and were correctly identified with the ATVS protocol. Agatston scores derived from the standard 120kVp (median, 33.4; IQR, 0-289.7) and the patient-tailored kV-independent protocol (median, 47.5; IQR, 0-287.5) showed no significant differences (p = 0.094). The intra-class correlation for Agatston scores derived from the two different protocols was excellent (ICC = 0.99). The mean dose-length-product was 29.8 ± 11.9 mGy × cm using the ATVS protocol and 31.7 ± 11.4 mGy × cm using the standard 120kVp protocol (p < 0.001). Additionally, 95% of patients were classified into the same risk category (0, 1-10, 11-100, 101-400, or > 400) using the patient-tailored protocol.

CONCLUSIONS

ATVS-based CACS, using a kV-independent algorithm, allows for high accuracy compared to the standard 120kVp scanning, while significantly reducing radiation dose parameters.

KEY POINTS

• ATVS allows for CT scanning with reduced radiation dose values. • KV-independent CACS is feasible at any tube voltage between 70 and 130 kVp. • ATVS applied to kV-independent CACS can significantly reduce the radiation dose.