Genetic Testing for Hypertriglyceridemia in Academic Lipid Clinics: Implications for Precision Medicine-Brief Report.

BACKGROUND: Severe hypertriglyceridemia is often caused by variants in genes of triglyceride metabolism. These variants include rare, heterozygous pathogenic variants (PVs), or multiple common, small-effect single nucleotide polymorphisms that can be quantified using a polygenic risk score (PRS). The role of genetic testing to examine PVs and PRS in predicting risk for pancreatitis and severity of hypertriglyceridemia is unknown. METHODS: We examined the relationship of PVs and PRSs associated with hypertriglyceridemia with the highest recorded plasma triglyceride level and risk for acute pancreatitis in 363 patients from 3 academic lipid clinics who underwent genetic testing (GBinsight's Dyslipidemia Comprehensive Panel). Categories of hypertriglyceridemia included: normal triglyceride (<200 mg/dL), moderate (200-499 mg/dL), severe (500-999 mg/dL), or very severe (≥1000 mg/dL). RESULTS: PVs and high PRSs were identified in 37 (10%) and 59 (16%) individuals, respectively. Patients with both had increased risk for very severe hypertriglyceridemia compared with those with neither genetic risk factor. Risk for acute pancreatitis was also increased in individuals with both genetic risk factors (odds ratio, 5.1 [P=0.02] after controlling for age, race, sex, body mass index, and highest triglyceride level), but not in individuals with PV or high PRS alone. CONCLUSIONS: The presence of both PV and high PRS significantly increased risk for very severe hypertriglyceridemia and acute pancreatitis, whereas PV or PRS alone only modestly increased risk. Genetic testing may help identify patients with hypertriglyceridemia who have the greatest risk for developing pancreatitis and may derive the greatest benefit from novel triglyceride-lowering therapies.

Diagnostic accuracy and performance of artificial intelligence in measuring left atrial volumes and function on multiphasic CT in patients with atrial fibrillation.

OBJECTIVES: To evaluate the effectiveness of a novel artificial intelligence (AI) algorithm for fully automated measurement of left atrial (LA) volumes and function using cardiac CT in patients with atrial fibrillation. METHODS: We included 79 patients (mean age 63 ± 12 years; 35 with atrial fibrillation (AF) and 44 controls) between 2017 and 2020 in this retrospective study. Images were analyzed by a trained AI algorithm and an expert radiologist. Left atrial volumes were obtained at cardiac end-systole, end-diastole, and pre-atrial contraction, which were then used to obtain LA function indices. Intraclass correlation coefficient (ICC) analysis of the LA volumes and function parameters was performed and receiver operating characteristic (ROC) curve analysis was used to compare the ability to detect AF patients. RESULTS: The AI was significantly faster than manual measurement of LA volumes (4 s vs 10.8 min, respectively). Agreement between the manual and automated methods was good to excellent overall, and there was stronger agreement in AF patients (all ICCs ≥ 0.877; p < 0.001) than controls (all ICCs ≥ 0.799; p < 0.001). The AI comparably estimated LA volumes in AF patients (all within 1.3 mL of the manual measurement), but overestimated volumes by clinically negligible amounts in controls (all by ≤ 4.2 mL). The AI's ability to distinguish AF patients from controls using the LA volume index was similar to the expert's (AUC 0.81 vs 0.82, respectively; p = 0.62). CONCLUSION: The novel AI algorithm efficiently performed fully automated multiphasic CT-based quantification of left atrial volume and function with similar accuracy as compared to manual quantification. Novel CT-based AI algorithm efficiently quantifies left atrial volumes and function with similar accuracy as manual quantification in controls and atrial fibrillation patients. KEY POINTS: • There was good-to-excellent agreement between manual and automated methods for left atrial volume quantification. • The AI comparably estimated LA volumes in AF patients, but overestimated volumes by clinically negligible amounts in controls. • The AI's ability to distinguish AF patients from controls was similar to the manual methods.

Genetic testing in ambulatory cardiology clinics reveals high rate of findings with clinical management implications.

PURPOSE: Cardiovascular disease (CVD) is the leading cause of death in adults in the United States, yet the benefits of genetic testing are not universally accepted. METHODS: We developed the "HeartCare" panel of genes associated with CVD, evaluating high-penetrance Mendelian conditions, coronary artery disease (CAD) polygenic risk, LPA gene polymorphisms, and specific pharmacogenetic (PGx) variants. We enrolled 709 individuals from cardiology clinics at Baylor College of Medicine, and samples were analyzed in a CAP/CLIA-certified laboratory. Results were returned to the ordering physician and uploaded to the electronic medical record. RESULTS: Notably, 32% of patients had a genetic finding with clinical management implications, even after excluding PGx results, including 9% who were molecularly diagnosed with a Mendelian condition. Among surveyed physicians, 84% reported medical management changes based on these results, including specialist referrals, cardiac tests, and medication changes. LPA polymorphisms and high polygenic risk of CAD were found in 20% and 9% of patients, respectively, leading to diet, lifestyle, and other changes. Warfarin and simvastatin pharmacogenetic variants were present in roughly half of the cohort. CONCLUSION: Our results support the use of genetic information in routine cardiovascular health management and provide a roadmap for accompanying research.

How Do We Incorporate Polygenic Risk Scores in Cardiovascular Disease Risk Assessment and Management?

PURPOSE OF REVIEW: The potential of polygenic risk scores (PRS) to improve atherosclerotic cardiovascular disease (ASCVD) risk assessment and management has stoked significant interest in their incorporation into clinical management. The goal of this review is to apprise the readers of the latest developments and evidence of PRS readiness for clinical integration. We also discuss current limitations that must be addressed before PRS can be implemented into routine clinical practice. RECENT FINDINGS: PRS have been shown to improve risk stratification for ASCVD and to identify patients who may derive increased benefit from primary and secondary prevention. Risk captured by PRS appears largely independent of traditional risk factors and can be ascertained at birth, prior to the development of traditional clinical risk factors. Genetic risk is modifiable through lifestyle modifications and medications. PRS offers a valuable way to improve early identification of actionable CVD risk. However, further work is needed before PRS can be implemented clinically.

Carcinoid Heart Disease: a Comprehensive Review.

PURPOSE OF REVIEW: Carcinoid heart disease is a rare disorder that is associated with significant morbidity and mortality. In this review of the literature, we will present current concepts in diagnosis and management of carcinoid heart disease. RECENT FINDINGS: Recent expert consensus guidelines highlight the role of echocardiography and screening with NT-proBNP for the evaluation of carcinoid heart disease. Advances in medical therapy along with better surgical outcomes highlight the experience and expertise that has been gained in the treatment of carcinoid heart disease. Carcinoid heart disease occurs in patients with neuroendocrine tumors who have carcinoid syndrome. Serotonin appears to play a central role in the development of carcinoid heart disease. Cardiac biomarkers and multimodality imaging can be used to aid in screening and diagnosis. The mainstay of treatment of carcinoid heart disease is surgery.

Identification of Thiobacillus bacteria in agricultural soil in Iran using the 16S rRNA gene.

Thiobacillus, as useful soil bacteria, plays an important role in sulfur cycling. The purpose of this study was to identify the species Thiobacillus thioparus, Thiobacillus novellas and Thiobacillus denitrificans in rainfed and irrigated lands soil in Ajabshir, Ilam, Qorveh, Rojintaak, Sonqor, Kermanshah and Research Farm of Razi University in Iran. Sampling was performed as randomized completely with three replications at depth of 0-30 cm. The Thiobacillus species were determined via 16S rRNA characteristics. The results of agarose gel electrophoresis indicated that T. thioparus was the highest amount in the irrigated land in Research Farm and its lowest amount was in the Rojintaak rainfed land. These species not found in four locations and conditions including the Ajabshir irrigated, Qorveh rainfed, Research Farm rainfed and Rojintaak irrigated lands. The results of the T. novellas indicated that this was found in Ilam irrigated, Qorveh rainfed, Research Farm irrigated, Rojintaak irrigated and Rojintaak rainfed lands. The highest and lowest amount of T. novellas was indicated in the Rojintaak and Ilam irrigated lands respectively. The T. denitrificans gene showed that this bacterium was observed only in both samples of Ajabshir. Our study showed that Thiobacillus was not detected in all of the soils. If sulfur fertilizer is given to the soil without this bacterium, it is necessary to use sulfur fertilizer with Thiobacillus bacteria inoculation for better sulfur oxidation.

Effect of planting time and vermicompost on the proteomic pattern of fenugreek (Trigonella foenum-graecum)

The fenugreek is one of the most important medicinal plants belongs to Fabaceae, originated in West Asia, Iran and Mediterranean regions. This research included a qualitative study of fenugreek proteins using SDS-PAGE electrophoresis on polyacrylamide gel and the separation of protein bands of fenugreek leaves in different treatments of vermicompost fertilizer and cultivating dates. Results showed that a band (about 80 kDa) on the first planting date (May 31) is observed in all samples except for sample a1 (10 t/ha vermicompost on May 31). Another significant difference was the band contained in the third planting date (31 September) and in the molecular weight of about 15 kDa, which was not seen in other dates. This difference can be due to the synthesis of this protein with the mentioned weight under the conditions of reducing the temperature in the early fall. It also showed more differences in two-dimensional electrophoresis, for example, in 14 kDa and PI in the range of 4.5-4.7 in treatment without fertilizer, no protein expression was observed, which was consistent with the results of the SDS-PAGE test.

Development of PCR primer systems for amplification of 16S-rDNA to detect of Thiobacillus spp.

Thiobacillus is a genus of Gram-negative, rod-shaped and autotrophic Betaproteobacteria. They catalyze the dissimilatory oxidation of elemental sulfur and reduced inorganic sulfur compounds. Whereas more than 30 species have been known in this genus, most were never reliably or effectively published. The rest were either reclassified into Thiomonas, Paracoccus, Starkeya, Sulfuriferula, Halothiobacillus, Thermithiobacillus or Acidithiobacillus, were lost from culture. Most of Thiobacillus species are obligate autotrophs via elementary sulfur, thiosulfate or polythionates as energy sources. Based on 16S ribosomal RNA sequence analysis, many members of Thiobacillus have been reclassified. A system was developed for the detection of Thiobacillus bacteria by the amplification of specific 16S ribosomal RNA sequence gene (16S rDNA) fragments with PCR. Primer sequences were designed for the amplification of fragments of 16S rDNA.

Experiential Narratives of Factors Limiting and Boosting Access to Support Services for Women with Obstetric Fistula in Southeast Nigeria.

PURPOSE: Obstetric fistula is a chronic health condition that leaves affected women battered and traumatized, thereby exposing them to social recluse life as a result of associated discomfort and odor. Support services to those with challenging health conditions are reputed to help cushion the adverse effects on them; thus women with fistula and other chronic diseases receiving adequate support will help them to cope and recuperate from such illnesses. This study explores the factors limiting and boosting access to support services for those with obstetric fistulainNigeria. MATERIALS AND METHOD: Focus Group Discussions and In-depth Interviews were employed to obtain data from 44 participants. The thematic data analysis method was deployed in analyzing the data collected. RESULTS: Factors like the limited number of fistula specialist doctors, poor funding, withdrawal from seeking help, long distance, and discrimination limit patients' access to support services and adequate fistula care. The study highlighted that community involvement in fistula care, adequate funding, training, and retraining of professionals will boost support services for fistula patients. CONCLUSION: The study recommends the adoption of a multidisciplinary approach in the management of obstetric fistula patients including the involvement of not only medical personnel but also social workers, families, groups, and community leaders.

Obstetric Fistula: Connecting the Interface between Social Work and Social Support Services for the Management and Reintegration of Victims in Ebonyi State, Nigeria.

Obstetric fistula is a chronic health condition that leaves affected women medically, socially, physically, and psychologically battered and traumatized. Those with the health condition live their lives as a social recluse because of the unpleasant smell the disease produces in them thereby making people avoid them. Adequate social support to those affected by the disease from all quarters has helped in the management and prevention of the health condition. This study, therefore, aims at exploring and connecting the link between social work and social support in the management of obstetric fistula in Nigeria and the reintegration of survivors into the society. The study adopted a qualitative approach using interviews and focus group discussions to collect data from 51 participants, and the data were thematically analyzed. The results of the study highlighted the potential roles of social workers in enhancing social support for the management and reintegration of victims of obstetric fistula in Nigeria. The findings also revealed challenges confronting social workers in enhancing social support in fistula victims. Findings from the study have implication for policy development, hence, the full involvement and expansion of the coverage of social workers in maternal and public health is recommended.

Diagnostic performance of fine needle aspiration cytology (FNAC) in the diagnosis of breast lumps.

OBJECTIVE: The aim of the study was to evaluate the diagnostic performance of line needle aspiration cytology in the diagnosis of breast lumps. METHODS: All patients who underwent FNA breast lumps at Rehman Medical Institute, Peshawar during 2006 to 2008 were included in this descriptive cross-sectional study. The FNA procedure was performed & interpreted by experienced cyto-pathologists. FNAC of 102 breast lumps were analysed. RESULTS: The age range of the patients was 15-80 years (mean 38.11 years). Inadequate cases were 2.94%, malignant 30.39%, atypical/suspicious of malignancy 6.86%, and benign 59.80%. Malignant lesions predominated in the 5th and 6th and benign in the 3rd and 4th decades of life. CONCLUSION: FNAC of breast is simple, cost-effective and less traumatic method for diagnosis of breast lumps. Combined with physical examination and imaging studies, it is a highly sensitive diagnostic tool and can reduce the need for open biopsy.

Interaction of iron and zinc fortification and late-season water deficit on yield and fatty acid composition of Dragon's Head (Lallemantia iberica L.).

Dragon's head (Lallemantia iberica) is a rich source of alpha-linolenic acid, linoleic acid, essential oil, protein, and mucilage. Therefore, the aim of this study was to evaluate the effects of foliar application of three different concentrations of Fe and Zn (control, 4, and 8 g lit-1) at two different developmental stages (vegetative stage (VS) and reproductive stage (RS)) on the quantity and quality of dragon's head seed yield and fatty acid composition in two crop seasons (2018 and 2019) under two environments (normal irrigation as control (NI) and post-anthesis water deficit (WD). In NI, average yields of seed, oil, and protein were 1155, 340, and 183 kg ha-1, respectively, and in the WD, they were 879, 283, and 148 kg ha-1, respectively. By applying Zn and Fe, the mean values of seed, oil, and protein yields in the NI were 1425, 478, and 264 kg ha-1, while in the WD, they were 1011, 354, and 200 kg ha-1, respectively. Furthermore, the application of WD resulted in a significant increase in zinc concentration, protein percentage, and saturated fatty acid percentage in seeds. Unlike WD, iron and zinc treatments decreased the percentage of saturated fatty acids and increased the percentage of unsaturated fatty acids. The number of capsules per plant had the most positive indirect effect on grain yield. The results showed that foliar spraying of Fe and Zn could effectively mitigate the adverse effects of WD on the quality and quantity of seed and oil yield dragon's head.

Potential of some microbial isolates on diesel hydrocarbons removal, bio surfactant production and biofilm formation.

Potential of Arthrobacter citreus B27Pet, Bacillus thuringiensis B48Pet and Candida catnulata to produce biosurfactant using four different carbon sources (naphthalene, hexadecane, diesel and petroleum crude oil) was investigated. Removal of petroleum crude oil from aqueous culture and degradation of diesel were also determined using single and mixed culture of strains. The biofilm existence in single and mixed culture of strains was considered using naphthalene, hexadecane and diesel in culture medium. Cell surface hydrophobicity of A. citreus was higher than other isolates which also showed maximum surface tension reduction and emulsification index. As a whole, remarkable biosurfactant production occurred using petroleum crude oil as a carbon source in medium. A. citreus was found to be more robust than other tested strains in removal efficiency of crude oil due to its biosurfactant production capability. Statistically significant positive correlation was observed between biofilm existence and surface tension using diesel and hexadecane as carbon source. Overall diesel biodegradation efficiency by the mix culture of three applied strains was about 75% within a short period of time (10 days) which was accompanied with high biofilm production.

Demographic and Regional Trends of Infective Endocarditis-Related Mortality in the United States, 1999 to 2019.

We sought to identify temporal, geographic, age and sex-based mortality trends of IE in the US over the past 2 decades. This population-based study utilized the CDC WONDER database to identify IE-related deaths occurring within the US between 1999 and 2019. IE-related crude and age-adjusted mortality rates (CMRs and AAMRs, respectively) were determined. Joinpoint regression was used to determine trends in CMR/AAMR using annual percent change (APC) in the overall sample in addition to demographic (sex, race/ethnicity, age) and geographic (rural/urban, statewide) subgroups. Between 1999 and 2019, a total of 279,154 deaths related to IE were reported. The overall AAMR declined from 54.2/1,000,000 in 1999 to 51.4 in 2019. However, AAMRs increased among several sub-groups over the past decade including men [2009-2019 APC = 0.4%, 95%CI, 0.1%-0.6%], non-Hispanic (NH) whites [APC of 0.8% from 2009 to 2019 (95%CI 0.5%-1.1%)], NH American Indians or Alaskan Natives [APC of 1.4% during the study period (95%CI, 0.7%-2.0%)], and those in rural areas [APC of 1.0% from 2009 to 2019 (95%CI 0.5%-1.5%)]. The CMRs increased among subjects 40-64 years old [APC of 2.8% from 2010 to 2019 (95%CI 2.2%-3.5%)] and 15-39 years old [APC of 16.4% from 2010 to 2017 (95%CI 13.5%-19.4%)]. IE-related CMR/AAMR increased among men, NH whites, NH American Indian or Alaskan Natives, those <65-year-old, and those from rural areas. Discerning the reasons for the increase in IE-related mortality among these groups and examining the impact of the social determinants of health may represent important opportunities to enhance care.

MMP-2 Associates With Incident Heart Failure and Atrial Fibrillation: The ARIC Study.

BACKGROUND: MMP (matrix metalloproteinase)-2 participates in extracellular matrix regulation and may be involved in heart failure (HF), atrial fibrillation (AF), and coronary heart disease. METHODS: Among the 4693 ARIC study (Atherosclerosis Risk in Communities) participants (mean age, 75±5 years; 42% women) without prevalent HF, multivariable Cox proportional hazard models were used to estimate associations of plasma MMP-2 levels with incident HF, HF with preserved ejection fraction (≥50%), HF with reduced ejection fraction (<50%), AF, and coronary heart disease. Mediation of the association between MMP-2 and HF was assessed by censoring participants who developed AF or coronary heart disease before HF. Multivariable linear regression models were used to assess associations of MMP-2 with measures of left ventricular and left atrial structure and function. RESULTS: Compared with the 3 lower quartiles, the highest MMP-2 quartile associated with greater risk of incident HF overall (adjusted hazard ratio, 1.48 [95% CI, 1.21-1.81]), incident HF with preserved ejection fraction (1.44 [95% CI, 1.07-1.94]), incident heart failure with reduced ejection fraction (1.48 [95% CI, 1.08-2.02]), and incident AF (1.44 [95% CI, 1.18-1.77]) but not incident coronary heart disease (0.97 [95% CI, 0.71-1.34]). Censoring AF attenuated the MMP-2 association with HF with preserved ejection fraction. Higher plasma MMP-2 levels were associated with larger left ventricular end-diastolic volume index, greater left ventricular mass index, higher E/e' ratio, larger left atrial volume index, and worse left atrial reservoir and contractile strains (all P<0.001). CONCLUSIONS: Higher plasma MMP-2 levels associate with diastolic dysfunction, left atrial dysfunction, and a higher risk of incident HF and AF. AF is a mediator of MMP-2-associated HF with preserved ejection fraction risk.

Cardiac computed tomographic imaging in cardio-oncology: An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT). Endorsed by the International Cardio-Oncology Society (ICOS).

Cardio-Oncology is a rapidly growing sub-specialty of medicine, however, there is very limited guidance on the use of cardiac CT (CCT) in the care of Cardio-Oncology patients. In order to fill in the existing gaps, this Expert Consensus statement comprised of a multidisciplinary collaboration of experts in Cardiology, Radiology, Cardiovascular Multimodality Imaging, Cardio-Oncology, Oncology and Radiation Oncology aims to summarize current evidence for CCT applications in Cardio-Oncology and provide practice recommendations for clinicians.

Rhizobacteria modify soil biological indices and induce tolerance to osmotic stress in tomato depending on the salinity level and bacteria species.

Salinity is a major abiotic stress that impacts crop productivity globally. Plant growth-promoting rhizobacteria (PGPRs) exploit several mechanisms to not only decrease soil salinity but also improve the systemic tolerance of plants to osmotic stress. In this work, the effect of five PGPR strains was investigated on the growth and physiological responses of tomato plants, including stomatal closure, proline, and K+ and Na+ content under a range of salt stress, 0, 2.5, 5, 7.5, and 10 dS m-1. The effect of PGPR strains and salinity levels on the soil biological characteristics was also investigated. Salt stress affected the plant growth and physiological factors and soil biological factors in a dose-dependent manner. The highest saline stress, 10 dS m-1, reduced shoot and root dry weight and root volume up to 51.3, 41.5, and 51.8%, respectively. It also increased stomatal resistance and proline content 2.01- and 3.66-folds and decreased K+/Na+ ratio 4.16-folds, respectively. It also reduced basal respiration, substrate-induced respiration, and microbial biomass carbon up to 2.25-, 4.83-, and 6.7-folds and increased qCO2 3.18-folds, respectively. PGPR strains were able to modulate salt tolerance mechanisms, improve plant growth factors, and improve soil biological indicators. Bacillus megaterium P2 was the best strain in the balancing K+/Na+ uptake at least at 10 dS m-1. However, the efficiency of strains was dependent on the magnitude of salt stress. Therefore, it is possible to introduce PGPR strains based on soil salt level or exploit rhizobacteria consortia to manage salt stress in different conditions.

Bridging the Gap: Investigating the Role of Social Workers in Supporting Metastatic Breast Cancer Patients in Nigeria.

Cancer is a disease common in every country around the globe with high incidences and deaths. Receiving a breast cancer diagnosis is often associated with a death sentence which makes the individual exhibit self-denial attributes, mixed negative emotions, depression, and anxiety. This study investigated the gap in supportive care and the role of social workers in the management of metastatic breast cancer patients in Nigeria. This study employed a qualitative method using Key Informant Interviews (KII). A total of 12 healthcare professionals in the area of medical social work, palliative care, and medical oncology were engaged in collecting the required information. The result revealed that social workers play significant roles in every aspect of the cancer care continuum - diagnosis, treatment, reintegration, or palliative care. Social workers help metastatic breast cancer patients in Nigeria, however, there are growing challenges to their roles. Most unskilled professionals often present themselves as social workers who do not meet professional standards or perform the best practice.

Investigating olfactory disorders in children with COVID-19 disease admitted to Hazrat Masoumeh Hospital in Qom.

BACKGROUND: One of the most important sensory disorders that usually occur after viral infections, especially human coronaviruses and rhinoviruses, is anosmia or loss of olfactory sense. The aim of the present study was to investigate olfactory disorders in children with COVID-19 disease admitted to Hazrat Masoumeh Hospital in Qom. MATERIALS AND METHODS: This descriptive-analytical study was conducted on 85 children admitted to Hazrat Masoumeh Hospital in Qom by using a convenience random sampling method. Data were collected using a checklist containing demographic data. The collected data were entered SPSS 18 software and were analyzed using descriptive and analytical statistics. RESULTS: In the present study, the results showed that the mean age of participants was 6.59 ± 3.27 years and more patients were Iranian (n = 69, 87.3%), had a history of underlying disease (n = 51, 64.6%), had a history of vaccination (n = 78, 98.7%), and did not have contact with a suspected patient (n = 43, 54.4%). Among the signs and symptoms of the disease, only the symptoms of fever (n = 71, 89.9%), weakness and lethargy (n = 44, 55.7%), and anorexia (n = 44, 55.7%) were observed in most patients. Moreover, 87.3% (n = 69) of the patients did not have olfactory. Furthermore, no association was found between age (P = 0.803), length of hospital stay (P = 0.397), white blood cell (P = 0.624), lymph (P = 0.638), Polymorphonuclear (PMN) (P = 0.493), erythrocyte sedimentation rate (P = 0.507), C-reactive protein (P = 0.085), and O2sat (P = 0.205) and olfactory disorders, but a significant relationship was found between patient weight (P = 0.002) and olfactory disorders. CONCLUSION: According to the results of the study, it can be said that in order to increase the strength of the immune system of children, especially overweight children, appropriate and planned action should be taken to prevent problems in these children.

The Prognostic Value of CAC Zero Among Individuals Presenting With Chest Pain: A Meta-Analysis.

BACKGROUND: There is little consensus on whether absence of coronary artery calcium (CAC) can identify patients with chest pain (CP) who can safely avoid additional downstream testing. OBJECTIVES: The purpose of this study was to conduct a systematic review and meta-analysis investigating the utility of CAC assessment for ruling out obstructive coronary artery disease (CAD) among patients with stable and acute CP, at low-to-intermediate risk of obstructive CAD undergoing coronary computed tomography angiography (CTA). METHODS: The authors searched online databases for studies published between 2005 and 2021 examining the relationship between CAC and obstructive CAD (≥50% coronary luminal narrowing) on coronary CTA among patients with stable and acute CP. RESULTS: In this review, the authors included 19 papers comprising 79,903 patients with stable CP and 13 papers including 12,376 patients with acute CP undergoing simultaneous CAC and coronary CTA assessment. Overall, 45% (95% CI: 40%-50%) of patients with stable CP and 58% (95% CI: 50%-66%) of patients with acute CP had CAC = 0. The negative predictive values for CAC = 0 ruling out obstructive CAD were 97% (95% CI: 96%-98%) and 98% (95% CI: 96%-99%) among patients with stable and acute CP, respectively. Additionally, the prevalence of nonobstructive CAD among those with CAC = 0 was 13% (95% CI: 10%-16%) among those with stable CP and 9% (95% CI: 5%-13%) among those with acute CP. A CAC score of zero predicted a low incidence of major adverse cardiac events among patients with stable CP (0.5% annual event rate) and acute CP (0.8% overall event rate). CONCLUSIONS: Among over 92,000 patients with stable or acute CP, the absence of CAC was associated with a very low prevalence of obstructive CAD, a low prevalence of nonobstructive CAD, and a low annualized risk of major adverse cardiac events. These findings support the role of CAC = 0 in a value-based health care delivery model as a "gatekeeper" for more advanced imaging among patients presenting with CP.