Effect of Elevated Temperature on Rhyolitic Rocks' Properties.

The effect of high temperatures on rock's thermophysical and mechanical properties is critical to the design of underground geotechnical applications. The current work investigates the impact of temperature on rhyolitic turf rock's physical and mechanical properties. Intact cylindrical core rock samples were heated to different temperatures (200, 400, 600, and 800 °C). The uniaxial compressive strength (UCS) and elastic modulus of unheated and heated samples were determined as important mechanical properties. In addition, the effect of temperature on the physical properties of rhyolite rock (density, color, and absorption) was investigated in conjunction with its microstructural properties. The hardening of the rhyolitic rock samples was observed below 600 °C, at which point the UCS and elastic modulus decreased to 78.0% and 75.9%, respectively, at 800 °C. The results also show that heating does not significantly affect the density and volume of permeable pore space, but a color change can be observed at 400 °C and above. A microscopic analysis shows the change in microstructural properties of rhyolite rock after heating to 600 °C. Furthermore, the SEM observations of heated materials show structural particle displacements and microcracking, leading to apparent surface cracks.

Influence of Friction Stir Process on the Physical, Microstructural, Corrosive, and Electrical Properties of an Al-Mg Alloy Modified with Ti-B Additives.

In this study, two successive methods were used to improve the grain structure and the mechanical and physical properties of Al 5052 aluminum alloy. The modifying elements, 0.99 wt.% of titanium (Ti) and 0.2 wt.% of boron (B), were added during the casting process. After solidification, single- and double-pass friction stir processing (FSP) were performed to achieve additional grain refinement and disperse the newly formed phases well. The addition of Ti-B modifiers significantly improved the mechanical and physical properties of the Al 5052 aluminum alloy. Nevertheless, only a 3% improvement in microhardness was achieved. The ultimate strength (US), yield strength (YS), and elastic modulus were investigated. In addition, the electrical conductivity was reduced by 56% compared to the base alloys. The effects of grain refinement on thermal expansion and corrosion rate were studied; the modified alloy with Ti-B in the as-cast state showed lower dimension stability than the samples treated with the FSP method. The grain refinement significantly affected the corrosion resistance; for example, single and double FSP passes reduced the corrosion rate by 11.4 times and 19.2 times, respectively. The successive FSP passes, resulting in a non-porous structure, increased the bulk density and formed precipitates with high bulk density.

Functional capacity and quality of life in the postural tachycardia syndrome: A retrospective cross-sectional study.

BACKGROUND: Postural tachycardia syndrome (POTS) is a complex syndrome of orthostatic intolerance that significantly affects quality of life. The relationship between functional capacity, quality of life, and age remains poorly understood in this patient population. The purpose of this cross-sectional study was to assess the clinical and exercise characteristics of patients with POTS who underwent exercise stress testing as part of cardiac rehabilitation, and to evaluate the relationships between functional capacity with age and sex, as well as the relationship between functional capacity and quality of life. METHODS: We included 255 consecutive adult patients with the diagnosis of POTS, by tilt table testing, who underwent exercise stress testing between 2012 and 2017. Clinical and stress test data were obtained from electronic medical records. RESULTS: Of the 255 patients, 232 (91%) were women, with median age 33.5 years. Prevalence of traditional CAD risk factors was low (2% diabetes, 13% hypertension, 7% hyperlipidemia, and 26% smoking history). Mean resting BP was 114 ± 13 mmHg systolic, resting HR was 76 ± 13 bpm, METs achieved 9.2 ± 2.2, and 1 min HR recovery 32 ± 17 bpm. 113 patients (44%) had abnormal functional capacity for age and sex. When analyzed by age groups, younger POTS patients had increasingly lower than expected functional capacity (compared to predicted normals) than did older patients (ANOVA P = 0.0017). The SF-36 physical component of patients with abnormal functional capacity was significantly lower than those with normal functional capacity. (p = 0.006). CONCLUSIONS: In this large cohort, patients with POTS were predominantly female (91%) and relatively young. The novel findings are that younger patients with POTS were more likely to have lower-than-average functional capacity for their age and sex compared to older patients, and that abnormal functional capacity was associated with lower quality of life by SF-36 physical component.

Lifestyle and Risk Factor Modification for Reduction of Atrial Fibrillation: A Scientific Statement From the American Heart Association.

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is associated with substantial morbidity, mortality, and healthcare use. Great strides have been made in stroke prevention and rhythm control strategies, yet reducing the incidence of AF has been slowed by the increasing incidence and prevalence of AF risk factors, including obesity, physical inactivity, sleep apnea, diabetes mellitus, hypertension, and other modifiable lifestyle-related factors. Fortunately, many of these AF drivers are potentially reversible, and emerging evidence supports that addressing these modifiable risks may be effective for primary and secondary AF prevention. A structured, protocol-driven multidisciplinary approach to integrate lifestyle and risk factor management as an integral part of AF management may help in the prevention and treatment of AF. However, this aspect of AF management is currently underrecognized, underused, and understudied. The purpose of this American Heart Association scientific statement is to review the association of modifiable risk factors with AF and the effects of risk factor intervention. Implementation strategies, care pathways, and educational links for achieving impactful weight reduction, increased physical activity, and risk factor modification are included. Implications for clinical practice, gaps in knowledge, and future directions for the research community are highlighted.

Familial hypercholesterolemia: Detect, treat, and ask about family.

Familial hypercholesterolemia is an autosomal dominant disorder that affects the metabolism of low-density lipo-protein cholesterol (LDL-C) through mutations in the gene for LDL receptor (LDLR), and less commonly in those for apolipoprotein B (APOB), proprotein convertase subtili-sin-kexin type 9 (PCSK9), and others. Patients with these mutations have elevated plasma levels of LDL-C and, as a result, an increased risk of atherosclerotic cardiovascular disease beginning in childhood, leading to significant risk of illness and death.

High Submaximal Exercise Heart Rate Impacts Exercise Intolerance in the Postural Orthostatic Tachycardia Syndrome.

PURPOSE: Exercise intolerance is a hallmark of the postural orthostatic tachycardia syndrome (POTS). However, no data are available on the implications of an exaggerated submaximal heart rate (HR) on exercise intolerance in patients. We investigated whether exaggerated HR responses occurring early on during incremental stress testing relate with increased odds of POTS and exercise intolerance. METHODS: Clinical characteristics and stress test HRs were compared between adults with POTS achieving ≥85% predicted metabolic equivalents (METs) (EX-TL, n = 101; body mass index [BMI] 24 ± 5 kg·m; 95% women) or <85% (EX-INTL, n = 71; BMI 28 ± 7 kg·m; 79% women) and sedentary controls (n = 30; BMI 36 ± 3 kg·m; 87% women). Multivariate logistic regressions were performed to estimate ORs and the probability of POTS and exercise intolerance associated with exercise HRs. RESULTS: Exercise tolerance was increased in EX-TL, but not in EX-INTL (10.0 ± 1.3 and 8.3 ± 1.5 METs vs 8.0 ± 1.6 METs, respectively) versus controls. Absolute peak HR was increased in EX-TL and EX-INTL versus controls (P < .01), whereas percent predicted did not differ. Exercise within the first-to-second stress stages was performed at exaggerated HRs (122 ± 17 bpm vs 103 ± 15 and 113 ± 15 bpm, P < .001) and percent HR reserve in EX-INTL versus controls and EX-TL (49% ± 12% vs 34% ± 11% and 41% ± 11%, P < .001), respectively. In multivariate analyses, peak HR was not significant, whereas increased submaximal HR (either variable) was associated with increased odds of EX-TL or EX-INTL. Lastly, odds of EX-INTL increased as METs decreased, whereas METs was not a predictor of EX-TL. CONCLUSIONS: An exaggerated submaximal exercise HR is predictive of POTS and exercise intolerance, and this chronotropic phenotype is exacerbated in patients achieving <85% predicted METs.

Correction to: ST­segment changes during tilt table testing for postural tachycardia syndrome: correlation with exercise stress test results.

Unfortunately, the 3rd author name was incorrectly published in the original publication. The complete correct name is given below.

ST-segment changes during tilt table testing for postural tachycardia syndrome: correlation with exercise stress test results.

BACKGROUND: Prior studies have reported ECG (Electrocardiogram) changes during tilt table testing (TTT), specifically during repolarization with ST-segment and T-wave changes. The correlation with ischemic evaluation remains unclear. The purpose of this study was to analyze the prevalence of ST-segment changes during TTT in a young, otherwise healthy population of patients with postural tachycardia syndrome (POTS), and correlate them with exercise stress test results. METHODS: Two hundred and fifty-five patients with POTS who underwent TTT and an exercise treadmill test (ETT) were analyzed. RESULTS: Forty-five had ST-segment changes/depressions during TTT (91% female, average age 36 years). Of the 45, three had ST-segment depression during ETT; all three had negative exercise stress echocardiograms (ESEs). Two others had ST-segment depressions on ETT (but not TTT), with negative ESEs. CONCLUSION: In a cohort of young, female, otherwise healthy patients with POTS, ST-segment changes occurred in a significant portion (18%) of patients during TTT. When evaluated with exercise stress testing, these patients had no evidence of underlying ischemia on ETT or ESE.

Association of Maternal Lactation With Diabetes and Hypertension: A Systematic Review and Meta-analysis.

Importance: Lactation has been shown to be associated with lower rates of diabetes and hypertension in mothers. However, the strength of association has varied between studies, and sample sizes are relatively small. Objective: To conduct a systematic review and meta-analysis to determine whether lactation is associated with a lower risk of diabetes and hypertension. Data Sources: Ovid MEDLINE, Ovid Embase, Cochrane CENTRAL, and CINAHL databases were searched from inception to July 2018 with manual search of the references. Study Selection: Studies of adult women that specified duration of breastfeeding for at least 12 months, evaluated primary hypertension and diabetes as outcomes, were full-text articles in English, and reported statistical outcomes as odds ratios were included. Data Extraction and Synthesis: Study characteristics were independently extracted using a standard spreadsheet template and the data were pooled using the random-effects model. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline for reporting was followed. Main Outcomes and Measures: Diabetes and hypertension. Results: The search yielded 1558 articles, from which a total of 6 studies met inclusion criteria for association between breastfeeding and diabetes and/or hypertension. The 4 studies included in the meta-analysis for the association between lactation and diabetes had a total of 206 204 participants, and the 5 studies included in the meta-analysis for the association between lactation and hypertension had a total of 255 271 participants. Breastfeeding for more than 12 months was associated with a relative risk reduction of 30% for diabetes (pooled odds ratio, 0.70 [95% CI, 0.62-0.78]; P < .001) and a relative risk reduction of 13% for hypertension (pooled odds ratio, 0.87 [95% CI, 0.78-0.97]; P = .01). Conclusions and Relevance: This study suggests that education about the benefits of breastfeeding for prevention of diabetes and hypertension in women is a low-risk intervention that can be easily included in daily practice and may have a positive impact on cardiovascular outcomes in mothers.

Temporal trends, ethnic determinants, and short-term and long-term risk of cardiac death in cancer patients: a cohort study.

BACKGROUND: We evaluated the risk of cardiac death in patients with prior cancer diagnoses and compared risk by cancer type and ethnicity in a large US population. METHOD: Utilizing the Surveillance, Epidemiology, and End Results database, data on patients with a cancer diagnosis between 2000 and 2014 were obtained. We calculated the standardized mortality ratio (SMR) of cardiac death after a cancer diagnosis and the excess risk per 10,000 person-years. We stratified the analysis according to the time interval between cancer and cardiac events, cancer site, cancer stage, and race. RESULTS: A total of 4,671,989 patients with a cancer diagnosis were included, of which 163,255 died due to cardiac causes within 10 years of diagnosis. We found a significantly higher rate of cardiac death for cancer patients [SMR=1.16, 95% confidence interval (CI) 1.15-1.16] compared to the general population. When observed for each cancer site, the highest SMR was after a diagnosis of hepatocellular carcinoma (SMR=2.58, 95% CI 2.45-2.72), pancreatic cancer (SMR=2.36, 95% CI 2.25-2.47), and lung cancer (SMR=2.30, 95% CI 2.27-2.34). Patients with metastatic disease had a higher rate of cardiac death (SMR=2.16, 95% CI 2.13-2.19). When stratified by ethnicity, SMR for cardiac death was 1.76, 2.28, 3.68, 2.65, and 1.84 for whites, blacks, American Indians/Alaska Natives, Asians/Pacific Islanders, and Hispanics, respectively. CONCLUSIONS: Cancer patients are more vulnerable to cardiac death than the general population, especially those with nonwhite ethnicity; liver, lung, and pancreatic cancers; and history of metastasis. Healthcare providers should be aware of this risk and pay particular attention to the highest-risk groups.

Visit-to-Visit Blood Pressure Variability, Coronary Atheroma Progression, and Clinical Outcomes.

Importance: Visit-to-visit blood pressure variability (BPV) is associated with cardiovascular events, but mechanisms and therapeutic implications underlying this association are not well understood. Objective: To examine the association of intraindividual BPV, coronary atheroma progression, and clinical outcomes using serial intravascular ultrasonography. Design, Setting, and Participants: Post hoc patient-level analysis of 7 randomized clinical trials conducted from 2004 to 2016 involving 3912 patients in multicenter, international, clinic-based primary and tertiary care centers. Adult patients with coronary artery disease who underwent serial intravascular ultrasonography in the setting of a range of medical therapies were included. Data were analyzed between November 2017 and March 2019. Exposures: Visit-to-visit BPV measured using intraindividual standard deviation over 3, 6, 12, 18, and 24 months. Main Outcomes and Measures: Percent atheroma volume (PAV) progression and major adverse cardiovascular events (defined as death, myocardial infarction, stroke, urgent revascularization for acute coronary syndrome, and hospitalization for unstable angina). Results: Of 3912 patients, the mean (SD) age was 58 (9) years, 1093 (28%) were women, and 3633 (93%) were white . Continuous change in PAV was significantly associated with systolic BPV (ß, .049; 95% CI, 0.021-0.078; P = .001), diastolic BPV (ß, .031; 95% CI, 0.002-0.059; P = .03), and pulse pressure variability (ß, .036; 95% CI, 0.006-0.067; P = .02), without a signal for differential effect greater than or less than a mean BP of 140/90 mm Hg. The PAV progression as a binary outcome was significantly associated with systolic BPV (odds ratio, 1.09; 95% CI, 1.01-1.17; P = .02) but not diastolic BPV (odds ratio, 1.04; 95% CI, 0.97-1.11; P = .30) or pulse pressure variability (odds ratio, 1.03; 95% CI, 0.96-1.10; P = .47). Survival curves revealed a significant stepwise association between cumulative major adverse cardiovascular events and increasing quartiles of systolic BPV (Kaplan-Meier estimates for quartiles 1-4: 6.1% vs 8.5% vs 10.1% vs 12.0%, respectively; log-rank P <.001). These distinct stepwise associations were not seen with diastolic BPV or pulse pressure variability. Conclusions and Relevance: Greater BPV, particularly systolic BPV, is significantly associated with coronary atheroma progression and adverse clinical outcomes. These data suggest maintaining stable blood pressure levels may be important to further improve outcomes in patients with coronary disease.

Correction: Hypertension guidelines.

In Aleyadeh W, Hutt-Centeno E, Ahmed HM, Shah NP. Hypertension guidelines: treat patients, not numbers. Cleve Clin J Med 2019; 86(1):47-56. doi:10.3949/ccjm.86a.18027, on page 50, the following statement was incorrect: "In 2017, the American College of Physicians (ACP) and the American Academy of Family Physicians (AAFP) recommended a relaxed systolic blood pressure target, ie, below 150 mm Hg, for adults over age 60, but a tighter goal of less than 130 mm Hg for the same age group if they have transient ischemic attack, stroke, or high cardiovascular risk.9" In fact, the ACP and AAFP recommended a tighter goal of less than 140 mm Hg for this higher-risk group. This has been corrected online.

Hypertension guidelines: Treat patients, not numbers.

The updated 2017 American College of Cardiology and American Heart Association (ACC/AHA) guidelines for managing hypertension advocate tighter blood pressure control than previous guidelines. This review summarizes the evidence behind the guidelines, discusses the risks and benefits of stricter blood pressure control, and provides our insights on blood pressure management in clinical practice.

Predictors of cardiorespiratory fitness improvement in phase II cardiac rehabilitation.

BACKGROUND: Cardiac rehabilitation (CR) improves cardiorespiratory fitness (CRF) and has been shown to reduce cardiovascular events and death. However, data about predictors of fitness improvement during CR are limited and conflicting. The objective of this study was to determine predictors of improvement in metabolic equivalents of task (METs) based on formal exercise testing throughout phase II CR. METHODS: We retrospectively reviewed 20 671 patients enrolled in phase II CR at our center from 2006 to 2016. Patients who completed 36 sessions and had entry and exit exercise stress tests were included for study. The short form-36 (SF-36) questionnaire was used to assess quality-of-life. Univariate and multivariate regression analyses were performed to determine independent predictors of METs improvement. RESULTS: Of the full cohort, 827 patients completed 36 sessions and had entry/exit stress test data. The majority of patients (N = 647, 78.2%) had improvement in METs (mean Δ 2.0 ± 1.2 METs), including patients ≥65 and < 65 years old (77% vs 79%, P = 0.46 for difference). METs improvement was negatively associated with body mass index, diabetes, left ventricular dysfunction, and poor baseline fitness; and positively associated with SF-36 score (P < 0.05 for all). After multivariable adjustment, improvement was no longer affected by age, ejection fraction, or baseline fitness. Patients with poor fitness (≤5 METS) and adequate fitness (> 5 METS) both had improvement, with no statistical difference between the groups (P = 0.36). CONCLUSIONS: In a large cohort of phase II CR patients, improvement in CRF was seen in the majority of patients across all ages, genders, and levels of baseline fitness.

Six-Year Changes in Physical Activity and the Risk of Incident Heart Failure: ARIC Study.

BACKGROUND: Higher physical activity (PA) is associated with lower heart failure (HF) risk; however, the effect of changes in PA on HF risk is unknown. METHODS: We evaluated 11 351 ARIC study (Atherosclerosis Risk in Communities) participants (mean age 60 years) who attended visit 3 (1993-1995) and did not have a history of cardiovascular disease. Exercise PA was assessed using a modified Baecke questionnaire and categorized according to American Heart Association guidelines as recommended, intermediate, or poor. We used Cox regression models to characterize the association of 6-year changes in PA between the first (1987-1989) and third ARIC visits and HF risk. RESULTS: During a median of 19 years of follow-up, 1750 HF events occurred. Compared with those with poor activity at both visits, the lowest HF risk was seen for those with persistently recommended activity (hazard ratio, 0.69; 95% confidence interval, 0.60-0.80). However, those whose PA increased from poor to recommended also had reduced HF risk (hazard ratio, 0.77; 95% confidence interval 0.63-0.93). Among participants with poor baseline activity, each 1 SD higher PA at 6 years (512.5 METS*minutes/week, corresponding to ≈30 minutes of brisk walking 4 times per week) was associated with significantly lower future HF risk (hazard ratio, 0.89, 95% confidence interval, 0.82-0.96). CONCLUSIONS: Although maintaining recommended activity levels is associated with the lowest HF risk, initiating and increasing PA, even in late middle age, are also linked to lower HF risk. Augmenting PA may be an important component of strategies to prevent HF.

Cardioprotective anti-hyperglycaemic medications: a review of clinical trials.

Despite extensive clinical efforts to achieve stricter glycaemic control over the past few decades, cardiovascular (CV) disease remains the leading cause of death among diabetic patients. Recently, sodium-glucose cotransporter-2 (SGLT-2) inhibitors and glucagon-like peptide-1 receptor (GLP-1-R) agonists have gained attention due to their apparent effects in reducing CV mortality. Four CV randomized controlled trials: EMPA-REG, CANVAS, LEADER, and SUSTAIN-6, found a decrease in CV events among patients with type 2 diabetes on empagliflozin, canagliflozin, liraglutide, and semaglutide, respectively. In light of this data, the US Food and Drug Administration has recently approved empagliflozin for CV mortality reduction in type 2 diabetic patients, making it the first diabetes medication approved for such an indication. The purpose of this review is to summarize the results of novel anti-hyperglycaemic medication trials, and shed light on their mode of action and cardioprotective pathways.

Usefulness of Coronary Artery Calcium to Predict Heart Failure With Preserved Ejection Fraction in Men Versus Women (from the Multi-Ethnic Study of Atherosclerosis).

We studied the association of coronary artery calcium (CAC) and risk of heart failure with preserved ejection fraction (HFpEF) among men and women in a multiethnic cohort. Coronary artery disease is a risk factor for development of HFpEF and assessment of subclinical atherosclerosis using CAC may allow for the early identification of patients at risk for HFpEF. We used data from the Multi-Ethnic Study of Atherosclerosis. CAC was measured at baseline in all participants. Incident HFpEF was defined as heart failure hospitalization with left ventricular ejection fraction ≥50%. Multivariable-adjusted Cox proportional hazards models were used to calculate HFpEF risk by CAC categories (0, 1 to 100, 101 to 300, and >300) and by CAC (continuous), stratified by gender and race/ethnicity. Of 6809 total participants, 127 incident HFpEF cases (1.8%) were ascertained. Mean age was 62 years (±10 years), and the participants were 53% female, 38% White, and 12% Black. In adjusted analysis, CAC >300 was associated with increased risk of HFpEF (hazard ratio [HR] 1.68, 95% confidence interval [95 CI] 1.00, 1.83); however, this was significant only in women (HR 2.82, 95% CI 1.32, 6.00 vs HR 0.91, 95% CI 0.46, 1.82 for men, interaction p = 0.03). Similarly, CAC modeled as a continuous variable was strongly predictive in women but not in men. In conclusion, measurement of CAC, a marker of coronary atherosclerosis, may stratify risk of HFpEF beyond traditional risk factors for women. Further investigation is needed to better understand potential gender differences in pathophysiology and presentation of HFpEF.