Serum magnesium and risk of sudden cardiac death in the Atherosclerosis Risk in Communities (ARIC) Study

Hypermagnesemia- and Hyperphosphatemia-Associated Cardiac Arrest after Injection of a Novel Magnesium-Based Bone Cement in Spinal Surgery

We report a case of pulseless electrical activity (PEA) associated with profound hypermagnesemia immediately after cementation of a novel magnesium-based cement in spine surgery. During T8 to T12 posterior instrumentation and decompression laminectomy for vertebral metastasis secondary to lung cancer, a 61-year-old Chinese woman developed sudden hypotension and went into PEA immediately after injection of a novel magnesium-based cement. Intraoperative fluoroscopic imaging did not show any notable cement extravasation. Resuscitation using intravenous epinephrine with five doses of 1-mg epinephrine in 1:10,000 dilution was instituted, and the patient had return of spontaneous circulation after 5 minutes. After successful resuscitation, surgery was expedited and completed. Intraoperative and postoperative investigations were notable for profound hypermagnesemia and hyperphosphatemia requiring diuresis. No echocardiographic or computerized tomographic evidence of pulmonary embolism was found. The patient was transferred to the surgical intensive care unit and remained on dual inotropic support over the next few days. She subsequently weaned off inotropic support and electrolyte imbalances resolved before making a full recovery. This case report demonstrates the severe magnesium toxicity and PEA related to the use of novel magnesium-based cement in spine surgery. Further studies need to be conducted to understand the potential complications related to its use and compare them to the standard bone cement implantation syndrome.

Effects of Different Cooking Processes on the Phytochemical Profile and Mineral Content of Garlic (Allium sativum L.)

In this study, the effects of different cooking processes on the phytochemical profile and mineral content of garlic (Allium sativum L.) were determined. Different cooking processes had a significant effect on the moisture, pH, water-soluble solids, L*, a*, b*, C* and °h values. The phenolic profile was generally better preserved in the steamed garlic samples than in the control samples. The mineral content of garlic prepared different cooking processes, with the exception of copper and magnesium, was found to be relatively high. As a result, the phenolic acid and mineral contents of garlic samples prepared with different cooking processes were better preserved and were closest to those of the control samples. In addition, to preserve the valuable compounds in garlic, adding them to dishes after the cooking process is completed is recommended.

The role of magnesium in cardiac arrest

Cardiac arrest is a leading cause of death globally. Only 25.8% of in-hospital and 33.5% of out-of-hospital individuals who achieve spontaneous circulation following cardiac arrest survive to leave the hospital. Respiratory failure and acute coronary syndrome are the two most common etiologies of cardiac arrest. Effort has been made to improve the outcomes of individuals resuscitated from cardiac arrest. Magnesium is an ion that is critical to the function of all cells and organs. It is often overlooked in everyday clinical practice. At present, there have only been a small number of reviews discussing the role of magnesium in cardiac arrest. In this review, for the first time, we provide a comprehensive overview of magnesium research in cardiac arrest focusing on the effects of magnesium on the occurrence and prognosis of cardiac arrest, as well as in the two main diseases causing cardiac arrest, respiratory failure and acute coronary syndrome. The current findings support the view that magnesium disorder is associated with increased risk of cardiac arrest as well as respiratory failure and acute coronary syndrome.

Serum Magnesium Levels and Cardiovascular Outcomes in Systolic Blood Pressure Intervention Trial Participants

Rationale and Objective

Serum magnesium levels have been inversely yet inconsistently associated with cardiovascular (CV) outcomes. In this study, we examined the association of serum magnesium levels with CV outcomes in the Systolic Blood Pressure Intervention Trial (SPRINT) participants.

Study Design

Case-control post hoc analysis of SPRINT.

Setting & Participants

A total of 2,040 SPRINT participants with available serum samples at baseline level were included in this study. Case participants (n = 510) who experienced a CV event during the SPRINT observation period (median follow-up of 3.2 years) and control participants (n = 1,530) without CV events were sampled in a 1:3 ratio for measurements of serum magnesium level at baseline and 2-year follow-up.

Predictors

Baseline serum magnesium levels and 2-year percentage change in serum magnesium levels (ΔSMg).

Outcome

SPRINT primary composite CV outcome.

Analytical Approach

Multivariable conditional logistic regression analysis, accounting for matching factors, was used to evaluate the association of baseline and ΔSMg with CV outcomes. Individual matching of cases and controls was based on the SPRINT treatment arm allocation (standard vs intensive) and prevalence of chronic kidney disease (CKD).

Results

The median serum magnesium level at baseline was similar among the case and control groups. In a fully adjusted model, each standard deviation (SD) (0.18 mg/dL) higher of the baseline serum magnesium level was independently associated with a lower risk for composite CV outcomes in all study participants (adjusted odds ratio 95% CI, 0.79 [0.70-0.89]). This association was similar when serum magnesium levels were analyzed in quartiles but dissipated in the standard (vs intensive) arm of SPRINT (0.88 [0.76-1.02] vs 0.65 [0.53-0.79], respectively; Pinteraction = 0.06). The presence or absence of CKD at baseline did not modify this association. ΔSMg was not independently associated with CV outcomes occurring after 2 years.

Limitations

ΔSMg was small in magnitude, limiting effect size.

Conclusions

Higher baseline serum magnesium levels were independently associated with reduced risk for CV outcomes in all study participants, but ΔSMg was not associated with CV outcomes.

Circulating magnesium as a potential risk stratification tool for sudden cardiac death: a systematic review

BACKGROUND

Sudden cardiac death (SCD) is one of the main causes of cardiovascular mortality and accounts for 15-20% of deaths worldwide. The current stratification strategy using depressed left ventricular ejection fraction is insufficient to stratify the risk of SCD, especially in the general population. In recent years, there has been increasing evidence showing the antiarrhythmic properties of magnesium. In this systematic review, the authors aim to determine circulating magnesium as a potential risk stratification tool for SCD.

METHODS

This systematic review was based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was conducted in July 2021 with sources from Google Scholar, PubMed, Science Direct, EBSCO Medline, and ProQuest.

RESULTS

A total of six studies were included in this review. Three studies conducted in the general population consistently showed lower risk of SCD in populations with high circulating magnesium. There was no association between circulating magnesium level and risk of SCD in intensive cardiac care unit (ICCU) patients, whilst the results were conflicting in congestive heart failure (CHF) patients.

CONCLUSION

High circulating magnesium might have the potential to be utilized as a risk stratification tool for SCD, especially in the general population. However, further study is needed to support this evidence.

Circulating Magnesium and Risk of Major Adverse Cardiac Events among Patients with Atrial Fibrillation in the ARIC Cohort

Background: Serum magnesium (Mg) has been reported to be inversely associated with the risk of atrial fibrillation (AF), coronary artery disease (CAD), and major adverse cardiovascular events (MACE). The association between serum Mg and the risk of MACE, heart failure (HF), stroke, and all-cause mortality among patients with AF has not been evaluated. Objective: We aim to examine whether higher serum Mg is associated with a lower risk of MACE, heart failure (HF), stroke, and all-cause mortality among patients with AF. Methods: We evaluated prospectively 413 participants of the Atherosclerosis Risk in Communities (ARIC) Study with a diagnosis of AF at the time of Mg measurement participating in visit 5 (2011-2013). Serum Mg was modeled in tertiles and as a continuous variable in standard deviation units. Endpoints (HF, MI, stroke, cardiovascular (CV) death, all-cause mortality, and MACE) were identified and modeled separately using Cox proportional hazard regression adjusting for potential confounders. Results: During a mean follow-up of 5.8 years, there were 79 HFs, 34 MIs, 24 strokes, 80 CV deaths, 110 MACEs, and 198 total deaths. After adjustment for demographic and clinical variables, participants in the second and third tertiles of serum Mg had lower rates of most endpoints, with the strongest inverse association for the incidence of MI (HR 0.20, 95% CI 0.07, 0.61) comparing top to bottom tertile. Serum Mg modeled linearly as a continuous variable did not show clear associations with endpoints except MI (HR 0.50, 95% CI 0.31, 0.80). Due to the limited number of events, the precision of most estimates of association was relatively low. Conclusions: Among patients with AF, higher serum Mg was associated with a lower risk of developing incident MI and, to a lesser extent, other CV endpoints. Further studies in larger patients with AF cohorts are needed to evaluate the role of serum Mg in preventing adverse CV outcomes in these patients.

The Role of Hypomagnesemia in Cardiac Arrhythmias: A Clinical Perspective

The importance of magnesium (Mg2+), a micronutrient implicated in maintaining and establishing a normal heart rhythm, is still controversial. It is known that magnesium is the cofactor of 600 and the activator of another 200 enzymatic reactions in the human organism. Hypomagnesemia can be linked to many factors, causing disturbances in energy metabolism, ion channel exchanges, action potential alteration and myocardial cell instability, all mostly leading to ventricular arrhythmia. This review article focuses on identifying evidence-based implications of Mg2+ in cardiac arrhythmias. The main identified benefits of magnesemia correction are linked to controlling ventricular response in atrial fibrillation, decreasing the recurrence of ventricular ectopies and stopping episodes of the particular form of ventricular arrhythmia called torsade de pointes. Magnesium has also been described to have beneficial effects on the incidence of polymorphic ventricular tachycardia and supraventricular tachycardia. The implication of hypomagnesemia in the genesis of atrial fibrillation is well established; however, even if magnesium supplementation for rhythm control, cardioversion facility or cardioversion success/recurrence of AF after cardiac surgery and rate control during AF showed some benefit, it remains controversial. Although small randomised clinical trials showed a reduction in mortality when magnesium was administered to patients with acute myocardial infarction, the large randomised clinical trials failed to show any benefit of the administration of intravenous magnesium over placebo.

Magnesium stable isotope composition, but not concentration, responds to obesity and early insulin-resistant conditions in minipig

Hypomagnesemia is frequently associated with type 2 diabetes and generally correlates with unfavorable disease progression, but the magnesium status in pre-diabetic conditions remains unclear. Here, the magnesium metabolism is scrutinized in a minipig model of obesity and insulin resistance by measuring variations of the metallome—the set of inorganic elements—and the magnesium stable isotope composition in six organs of lean and obese minipigs raised on normal and Western-type diet, respectively. We found that metallomic variations are most generally insensitive to lean or obese phenotypes. The magnesium stable isotope composition of plasma, liver, kidney, and heart in lean minipigs are significantly heavier than in obese minipigs. For both lean and obese minipigs, the magnesium isotope composition of plasma and liver were negatively correlated to clinical phenotypes and plasma lipoproteins concentration as well as positively correlated to hyperinsulinemic-euglycemic clamp output. Because the magnesium isotope composition was not associated to insulin secretion, our results suggest that it is rather sensitive to whole body insulin sensitivity, opening perspectives to better comprehend the onset of insulin-resistant diabetic conditions.

Magnesium supplementation reduces inflammation in rats with induced chronic kidney disease

BACKGROUND

Inflammation is a common feature in chronic kidney disease (CKD) that appears specifically associated with cardiovascular derangements in CKD patients. Observational studies have revealed a link between low Mg levels and inflammation. In this study, we hypothesize that Mg might have a modulatory effect on the inflammation induced under the uraemic milieu.

METHODS

In vivo studies were performed in a 5/6 nephrectomized rat model of CKD. Furthermore, a possible direct effect of Mg was addressed through in vitro studies with vascular smooth muscle cells (VSMCs).

RESULTS

Uraemic rats fed a normal (0.1%) Mg diet showed a systemic inflammatory response evidenced by the elevation in plasma of the pro-inflammatory cytokines TNF-α, IL-1β and IL-6, and GPx activity, a marker of oxidative stress. Importantly, an increased expression of these cytokines in the aortic tissue was also observed. In contrast, a dietary Mg supplementation (0.6%) greatly prevented the oxidative stress and the pro-inflammatory response. In vitro, in VSMCs cultured in a pro-inflammatory high phosphate medium, incubation with Mg 1.6 mM inhibited the increase in the production of ROS, the rise in the expression of TNF-α, IL-1β, IL-6 and IL-8 and the activation of NF-κB signalling that was observed in cells incubated with a normal (0.8 mM) Mg.

CONCLUSION

Mg supplementation reduced inflammation associated with CKD, exerting a direct effect on vascular cells. These findings support a possible beneficial effect of Mg supplementation along the clinical management of CKD patients.

An overview of diagnosis and management of drug-induced hypomagnesemia

Magnesium (Mg) is commonly addressed as the "forgotten ion" in medicine. Nonetheless, hypomagnesemia should be suspected in clinical practice in patients with relevant symptomatology and also be considered a predisposing factor for the development of other electrolyte disturbances. Furthermore, chronic hypomagnesemia has been associated with diabetes mellitus and cardiovascular disease. Hypomagnesemia as a consequence of drug therapy is relatively common, with the list of drugs inducing low serum Mg levels expanding. Culprit medications linked to hypomagnesemia include antibiotics (e.g. aminoglycosides, amphotericin B), diuretics, antineoplastic drugs (cisplatin and cetuximab), calcineurin inhibitors, and proton pump inhibitors. In recent years, the mechanisms of drug-induced hypomagnesemia have been unraveled through the discovery of key Mg transporters in the gut and kidney. This narrative review of available literature focuses on the pathogenetic mechanisms underlying drug-induced hypomagnesemia in order to increase the insight of clinicians toward early diagnosis and effective management.

Sudden Cardiac Death in Patients with Heart Disease and Preserved Systolic Function: Current Options for Risk Stratification

Sudden cardiac death (SCD) is the leading cause of cardiovascular mortality in patients with coronary artery disease without severe systolic dysfunction and in heart failure with preserved ejection fraction. From a global health perspective, while risk may be lower, the absolute number of SCDs in patients with left ventricle ejection fraction >35% is higher than in those with severely reduced left ventricle ejection fraction (defined as ≤35%). Despite these observations and the high amount of available data, to date there are no clear recommendations to reduce the sudden cardiac death burden in the population with mid-range or preserved left ventricle ejection fraction. Ongoing improvements in risk stratification based on electrophysiological and imaging techniques point towards a more precise identification of patients who would benefit from ICD implantation, which is still an unmet need in this subset of patients. The aim of this review is to provide a state-of-the-art approach in sudden cardiac death risk stratification of patients with mid-range and preserved left ventricular ejection fraction and one of the following etiologies: ischemic cardiomyopathy, heart failure, atrial fibrillation or myocarditis.

Magnesium: Biochemistry, Nutrition, Detection, and Social Impact of Diseases Linked to Its Deficiency

Magnesium plays an important role in many physiological functions. Habitually low intakes of magnesium and in general the deficiency of this micronutrient induce changes in biochemical pathways that can increase the risk of illness and, in particular, chronic degenerative diseases. The assessment of magnesium status is consequently of great importance, however, its evaluation is difficult. The measurement of serum magnesium concentration is the most commonly used and readily available method for assessing magnesium status, even if serum levels have no reliable correlation with total body magnesium levels or concentrations in specific tissues. Therefore, this review offers an overview of recent insights into magnesium from multiple perspectives. Starting from a biochemical point of view, it aims at highlighting the risk due to insufficient uptake (frequently due to the low content of magnesium in the modern western diet), at suggesting strategies to reach the recommended dietary reference values, and at focusing on the importance of detecting physiological or pathological levels of magnesium in various body districts, in order to counteract the social impact of diseases linked to magnesium deficiency.

The ECG Characteristics of Patients With Isolated Hypomagnesemia

Background

Electrocardiographic (ECG) characteristics of patients with isolated hypomagnesemia are not well defined. We aimed to investigate these ECG characteristics in order to define clearly the features of isolated hypomagnesemia.

Hypothesis

Lower serum magnesium could affect ECG parameters after excluding potential confounders.

Methods

This retrospective study was of patients with low serum magnesium <0.65 mmol/L compared with the same patients after restoration to normal serum magnesium. Patients with hypokalemia, hypocalcemia and other electrolyte disturbances were excluded. ECG parameters manually determined and analyzed were P wave dispersion, PR interval, QRS duration, ST-T changes, T wave amplitude, T peak-to-end interval (Tpe), corrected Tpe (Tpec), QT, corrected QT (QTc), QT peak corrected (QTpc) and Tpe dispersion, Tpe/QT ratio.

Results

Two-hundred-and-fourteen patients with isolated hypomagnesemia were identified with 50 of them (56.9 ± 13.6 years; 25 males) being eligible for final analysis from 270,997 patients presenting April 2011–October 2017. In the period of isolated hypomagnesemia, P wave duration was found prolonged (p ≤ 0.02); as was QTc (439 ± 27 vs. 433 ± 22, p = 0.01). Tpec (122 ± 24vs. 111 ± 22, p = 0.000) and Tpe/QT ratio (0.29 ± 0.05 vs. 0.27 ± 0.05, p = 0.000) were increased. QTpc decreased during hypomagnesemia (334 ± 28 vs. 342 ± 21, p = 0.02). However, no significant differences were found in PR interval, QRS duration (85 ± 12 ms vs. 86 ± 12 ms, p = 0.122) and ST-T segments between the patients and their own controls.

Conclusions

In patients with isolated hypomagnesemia, P wave duration, QTc, Tpec, and Tpe/QT ratio suggesting atrial depolarization and ventricular repolarization dispersion were significantly increased compared with normal magnesium levels in the same patients after restoration to normal levels.

Serum magnesium, bone-mineral metabolism markers and their interactions with kidney function on subsequent risk of peripheral artery disease: the Atherosclerosis Risk in Communities Study

BACKGROUND

Few studies have investigated the association of magnesium levels with incident peripheral artery disease (PAD) despite emerging evidence of magnesium contributing to vascular calcification. Moreover, no data are available on whether the magnesium-PAD relationship is independent of or modified by kidney function.

METHODS

A cohort of 11 839 participants free of PAD in the Atherosclerosis Risk in Communities Study at Visit 2 (1990-92) was studied. We investigated the association of serum magnesium and other bone-mineral metabolism markers [calcium, phosphorus, intact parathyroid hormone (iPTH) and intact fibroblast growth factor-23] with incident PAD using multivariable Cox proportional hazards regression.

RESULTS

Over a median of 23 years, there were 471 cases of incident PAD. The hazard ratio for incident PAD in Quartile 1 (<1.5 mEq/L) versus Quartile 4 (>1.7 mEq/L) of magnesium was 1.96 (95% confidence interval 1.40-2.74) after adjustment for potential confounders. Lower magnesium levels were associated with greater incidence of PAD, particularly in those with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 (n = 11 606). In contrast, the association was largely flat in those with eGFR <60 mL/min/1.73 m2 (n = 233) with P-for-interaction 0.03. Among bone-mineral metabolism markers, only higher iPTH showed an interaction with kidney function (P-for-interaction 0.01) and iPTH >65 pg/mL was significantly related to PAD only in those with eGFR <60 mL/min/1.73 m2.

CONCLUSIONS

Lower magnesium was independently associated with incident PAD, but this association was significantly weaker in those with reduced kidney function. In contrast, higher iPTH levels were particularly related to PAD risk in this clinical population.

Quantitative Association Between Serum/Dietary Magnesium and Cardiovascular Disease/Coronary Heart Disease Risk: A Dose-Response Meta-analysis of Prospective Cohort Studies

BACKGROUND

The quantitative association between serum/dietary magnesium and cardiovascular disease (CVD) remains unclear. We conducted a dose-response meta-analysis to evaluate the quantitative association between serum/dietary magnesium and CVD, including coronary heart disease (CHD).

METHODS

PubMed, China National Knowledge Infrastructure, and Web of Science were searched for publications. STATA 12.0 was used to analyze data. We used the random-effects model to reduce heterogeneity.

RESULTS

Eighteen prospective cohort studies with 544,581 participants and 22,658 CVD cases were included. The follow-up duration was 1-28 years. The pooled relative risk (RR) of CVD for the relatively normal versus lowest serum and dietary magnesium level was 0.64 {[95% confidence interval (CI): 0.51-0.80] and 0.90 [95% CI: 0.84-0.96]}. The pooled RR of CHD for the relatively normal versus lowest serum and dietary magnesium level was 0.70 (95% CI: 0.57-0.85) and 0.86 (95% CI: 0.77-0.94). We noted a significant association between increasing serum magnesium levels (per 0.1-mg/dL increase) and risk of CVD (RR: 0.93, 95% CI: 0.88-0.97) and CHD (RR: 0.90, 95% CI: 0.84-0.96) and between dietary magnesium levels (per 100-mg/d increase) and risk of CVD (RR: 0.90, 95% CI: 0.83-0.96) and CHD (RR: 0.92, 95% CI: 0.82-0.98). Serum/dietary Mg level comparisons presented a 7%-10% decrease in CVD/CHD risk. The dose-response meta-analyses showed linear relationships between serum magnesium and CVD (Pnonlinearity = 0.833) or CHD (Pnonlinearity = 0.193) and dietary magnesium and CVD (Pnonlinearity = 0.463) or CHD (Pnonlinearity = 0.440).

CONCLUSIONS

Increasing dietary magnesium or serum magnesium level is linearly and inversely associated with the risk of total CVD and CHD events.

Relationship Between Dietary Magnesium Intake and Incident Heart Failure Among Older Women: The WHI

Background

Women represent a large proportion of the growing heart failure (HF) epidemic, yet data are lacking regarding optimal dietary and lifestyle prevention strategies for them. Specifically, the association between magnesium intake and HF in a multiracial cohort of women is uncertain.

Methods and Results

We included 97 725 postmenopausal women from the WHI (Women's Health Initiative) observational studies and placebo arms of the hormone trial. Magnesium intake was measured at baseline by a 122‐item validated food‐frequency questionnaire and stratified into quartiles based on diet only, total intake (diet with supplements), and residual intake (calibration by total energy). Incident hospitalized HF (2153 events, median follow‐up 8.1 years) was adjudicated by medical record abstraction. In Cox proportional hazards models, we evaluated the association between magnesium intake and HF adjusting for potential confounders. Analyses were repeated on a subcohort (n=18 745; median‐follow‐up, 13.2 years) for whom HF cases were subclassified into preserved ejection fraction (526 events), reduced ejection fraction (291 events) or unknown (168 events). Most women were white (85%) with a mean age of 63. Compared with the highest quartile of magnesium intake, women in the lowest quartile had an increased risk of incident HF, with adjusted hazard ratios of 1.32 (95% CI, 1.02–1.71) for diet only (P trend=0.03), 1.26 (95% CI, 1.03–1.56) for total intake, and 1.31 (95% CI, 1.02–1.67) for residual intake. Results did not significantly vary by race. Subcohort analyses showed low residual magnesium intake was associated with HF with reduced ejection fraction (hazard ratio, 1.81, lowest versus highest quartile; 95% CI, 1.08–3.05) but not HF with preserved ejection fraction.

Conclusions

Low magnesium intake in a multiracial cohort of postmenopausal women was associated with a higher risk of incident HF, especially HF with reduced ejection fraction.

Environmental heavy metals and cardiovascular diseases: Status and future direction

Cardiovascular disease (CVD) and environmental degradation are leading global health problems of our time. Recent studies have linked exposure to heavy metals to the risks of CVD and diabetes, particularly in populations from low- and middle-income countries, where concomitant rapid development occurs. In this review, we 1) assessed the totality, quantity, and consistency of the available epidemiological studies, linking heavy metal exposures to the risk of CVD (including stroke and coronary heart disease); 2) discussed the potential biological mechanisms underlying some tantalizing observations in humans; and 3) identified gaps in our knowledge base that must be investigated in future work. An accumulating body of evidence from both experimental and observational studies implicates exposure to heavy metals, in a dose-response manner, in the increased risk of CVD. The limitations of most existing studies include insufficient statistical power, lack of comprehensive assessment of exposure, and cross-sectional design. Given the widespread exposure to heavy metals, an urgent need has emerged to investigate these putative associations of environmental exposures, either independently or jointly, with incident CVD outcomes prospectively in well-characterized cohorts of diverse populations, and to determine potential strategies to prevent and control the impacts of heavy metal exposure on the cardiometabolic health outcomes of individuals and populations.

Racial Differences in Sudden Cardiac Death

BACKGROUND

Blacks have a higher incidence of out-of-hospital sudden cardiac death (SCD) in comparison with whites. However, the racial differences in the cumulative risk of SCD and the reasons for these differences have not been assessed in large-scale community-based cohorts. The objective of this study is to compare the lifetime cumulative risk of SCD among blacks and whites, and to evaluate the risk factors that may explain racial differences in SCD risk in the general population.

METHODS

This is a cohort study of 3832 blacks and 11 237 whites participating in the Atherosclerosis Risk in Communities Study (ARIC). Race was self-reported. SCD was defined as a sudden pulseless condition from a cardiac cause in a previously stable individual, and SCD cases were adjudicated by an expert committee. Cumulative incidence was computed using competing risk models. Potential mediators included demographic and socioeconomic factors, cardiovascular risk factors, presence of coronary heart disease, and electrocardiographic parameters as time-varying factors.

RESULTS

The mean (SD) age was 53.6 (5.8) years for blacks and 54.4 (5.7) years for whites. During 27.4 years of follow-up, 215 blacks and 332 whites experienced SCD. The lifetime cumulative incidence of SCD at age 85 years was 9.6, 6.6, 6.5, and 2.3% for black men, black women, white men, and white women, respectively. The sex-adjusted hazard ratio for SCD comparing blacks with whites was 2.12 (95% CI, 1.79-2.51). The association was attenuated but still statistically significant in fully adjusted models (hazard ratio, 1.38; 95% CI, 1.11-1.71). In mediation analysis, known factors explained 65.3% (95% CI 37.9-92.8%) of the excess risk of SCD in blacks in comparison with whites. The single most important factor explaining this difference was income (50.5%), followed by education (19.1%), hypertension (22.1%), and diabetes mellitus (19.6%). Racial differences were evident in both genders but stronger in women than in men.

CONCLUSIONS

Blacks had a much higher risk for SCD in comparison with whites, particularly among women. Income, education, and traditional risk factors explained ≈65% of the race difference in SCD. The high burden of SCD and the racial-gender disparities observed in our study represent a major public health and clinical problem.

Association of Dietary Magnesium Intake with Fatal Coronary Heart Disease and Sudden Cardiac Death

Background: Postmenopausal women represent the highest population-based burden of cardiovascular disease, including sudden cardiac death (SCD). Our understanding of the etiology and risk factors contributing to fatal coronary heart disease (CHD) and SCD, particularly among women, is limited. This study examines the association between dietary magnesium intake and fatal CHD and SCD. Materials and Methods: We examined 153,569 postmenopausal women who participated in the Women's Health Initiative recruited between 1993 and 1998. Magnesium intake at baseline was assessed using a validated food frequency questionnaire, adjusting for energy via the residual method. Fatal CHD and SCD were identified over an average follow-up of 10.5 years. Results: For every standard deviation increase in magnesium intake, there was statistically significant risk reduction, after adjustment for confounders, of 7% for fatal CHD (hazard ratio [HR] 0.93, 95% confidence interval [CI] 0.89-0.97), and 18% risk reduction for SCD (HR 0.82, 95% CI 0.58-1.15) the latter of which did not reach statistical significance. In age-adjusted quartile analysis, women with the lowest magnesium intake (189 mg/day) had the greatest risk for fatal CHD (HR 1.54, 95% CI 1.40-1.69) and SCD (HR 1.70, 95% CI 0.94-3.07). This association was attenuated in the fully adjusted model, with HRs of 1.19 (95% CI 1.06-1.34) for CHD and 1.24 (95% CI 0.58-2.65) for SCD for the lowest quartile of magnesium intake. Conclusions: This study provides evidence of a potential inverse association between dietary magnesium and fatal CHD and a trend of magnesium with SCD in postmenopausal women. Future studies should confirm this association and consider clinical trials to test whether magnesium supplementation could reduce fatal CHD in high-risk individuals.

Seeds

A wide variety of plant species provide edible seeds. Seeds are the dominant source of human calories and protein. The most important and popular seed food sources are cereals, followed by legumes and nuts. Their nutritional content of fiber, protein, and monounsaturated/polyunsaturated fats make them extremely nutritious. They are important additions to our daily food consumption. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol, and blood pressure.

Association of Dietary Magnesium Intake with Fatal Coronary Heart Disease and Sudden Cardiac Death

Background: Postmenopausal women represent the highest population-based burden of cardiovascular disease, including sudden cardiac death (SCD). Our understanding of the etiology and risk factors contributing to fatal coronary heart disease (CHD) and SCD, particularly among women, is limited. This study examines the association between dietary magnesium intake and fatal CHD and SCD. Materials and Methods: We examined 153,569 postmenopausal women who participated in the Women's Health Initiative recruited between 1993 and 1998. Magnesium intake at baseline was assessed using a validated food frequency questionnaire, adjusting for energy via the residual method. Fatal CHD and SCD were identified over an average follow-up of 10.5 years. Results: For every standard deviation increase in magnesium intake, there was statistically significant risk reduction, after adjustment for confounders, of 7% for fatal CHD (hazard ratio [HR] 0.93, 95% confidence interval [CI] 0.89-0.97), and 18% risk reduction for SCD (HR 0.82, 95% CI 0.58-1.15) the latter of which did not reach statistical significance. In age-adjusted quartile analysis, women with the lowest magnesium intake (189 mg/day) had the greatest risk for fatal CHD (HR 1.54, 95% CI 1.40-1.69) and SCD (HR 1.70, 95% CI 0.94-3.07). This association was attenuated in the fully adjusted model, with HRs of 1.19 (95% CI 1.06-1.34) for CHD and 1.24 (95% CI 0.58-2.65) for SCD for the lowest quartile of magnesium intake. Conclusions: This study provides evidence of a potential inverse association between dietary magnesium and fatal CHD and a trend of magnesium with SCD in postmenopausal women. Future studies should confirm this association and consider clinical trials to test whether magnesium supplementation could reduce fatal CHD in high-risk individuals.

Prospective Countywide Surveillance and Autopsy Characterization of Sudden Cardiac Death: POST SCD Study

BACKGROUND

Studies of out-of-hospital cardiac arrest and sudden cardiac death (SCD) use emergency medical services records, death certificates, or definitions that infer cause of death; thus, the true incidence of SCD is unknown. Over 90% of SCDs occur out-of-hospital; nonforensic autopsies are rarely performed, and therefore causes of death are presumed. We conducted a medical examiner-based investigation to determine the precise incidence and autopsy-defined causes of all SCDs in an entire metropolitan area. We hypothesized that postmortem investigation would identify actual sudden arrhythmic deaths among presumed SCDs.

METHODS

Between February 1, 2011, and March 1, 2014, we prospectively identified all incident deaths attributed to out-of-hospital cardiac arrest (emergency medical services primary impression, cardiac arrest) between 18 to 90 years of age in San Francisco County for autopsy, toxicology, and histology via medical examiner surveillance of consecutive out-of-hospital deaths, all reported by law. We obtained comprehensive records to determine whether out-of-hospital cardiac arrest deaths met World Health Organization (WHO) criteria for SCD. We reviewed death certificates filed quarterly for missed SCDs. Autopsy-defined sudden arrhythmic deaths had no extracardiac cause of death or acute heart failure. A multidisciplinary committee adjudicated final cause.

RESULTS

All 20 440 deaths were reviewed; 12 671 were unattended and reported to the medical examiner. From these, we identified 912 out-of-hospital cardiac arrest deaths; 541 (59%) met WHO SCD criteria (mean 62.8 years, 69% male) and 525 (97%) were autopsied. Eighty-nine additional WHO-defined SCDs occurred within 3 weeks of active medical care with the death certificate signed by the attending physician, ineligible for autopsy but included in the countywide WHO-defined SCD incidence of 29.6/100 000 person-years, highest in black men (P<0.0001). Of 525 WHO-defined SCDs, 301 (57%) had no cardiac history. Leading causes of death were coronary disease (32%), occult overdose (13.5%), cardiomyopathy (10%), cardiac hypertrophy (8%), and neurological (5.5%). Autopsy-defined sudden arrhythmic deaths were 55.8% (293/525) of overall, 65% (78/120) of witnessed, and 53% (215/405) of unwitnessed WHO-defined SCDs (P=0.024); 286 of 293 (98%) had structural cardiac disease.

CONCLUSIONS

Forty percent of deaths attributed to stated cardiac arrest were not sudden or unexpected, and nearly half of presumed SCDs were not arrhythmic. These findings have implications for the accuracy of SCDs as defined by WHO criteria or emergency medical services records in aggregate mortality data, clinical trials, and cohort studies.

Serum Magnesium is associated with Carotid Atherosclerosis in patients with high cardiovascular risk (CORDIOPREV Study)

This study aimed to ascertain whether there is an independent association between serum magnesium (Mg) and the Carotid Intima-Media Thickness (IMT-CC), a well-accepted atherosclerotic-biomarker surrogate of cardiovascular disease (CVD), in a population with high cardiovascular risk. Serum Mg and traditional atherosclerotic risk factors were recorded in 939 patients (mean age, 59.6 ± 0.3 years, 83.2% men) with coronary heart disease (CHD) enrolled in the CORDIOPREV trial. Serum Mg strongly associated with IMT-CC. Before adjusting for potential confounding factors, IMT-CC decreased by 0.111 ± 0.011 mm per mg/dl increase in serum Mg (p < 0.001). After adjustment, the effect of Mg did not appear mediated through factors related to glucose metabolism, the lipid profile or the mineral metabolism and renal function. Multivariate models showed the lower Mg levels (quartile 1) as a strong independent factor contributing to IMT-CC along with age, sex, SBP, HDL-C, and diuretic use. Logistic regression analysis confirmed the predictive ability of serum Mg to differentiate patients at higher atherosclerotic risk as defined by an IMT-CC ≥ 1.0 mm, yielding a OR for the lower quartile of 10.623 (95%CI 2.311–48.845; P = 0.002) and a ROC-derived cutoff of 1.61 mg/dl. Therefore, our findings outline low serum magnesium as a possible independent risk factor for carotid atherosclerosis.

Prevention of Cardiovascular Disease: Screening for Magnesium Deficiency

Magnesium is an essential mineral naturally present in the human body, where it acts as cofactor in several enzymatic reactions. Magnesium is a key cardiovascular regulator, which maintains electrical, metabolic, and vascular homeostasis. Moreover, magnesium participates in inflammation and oxidative processes. In fact, magnesium deficiency is involved in the pathophysiology of arterial hypertension, diabetes mellitus, dyslipidemia, metabolic syndrome, endothelial dysfunction, coronary artery disease, cardiac arrhythmias, and sudden cardiac death. In consideration of the great public-health impact of cardiovascular disease, the recognition of the negative effects of magnesium deficiency suggests the possible role of hypomagnesaemia as cardiovascular risk factor and the use of serum magnesium level for the screening and prevention of cardiovascular risk factors and cardiovascular diseases. Moreover, it might help with the identification of new therapeutical strategies for the management of cardiovascular disease through magnesium supplementation.

Association between exposure to desalinated sea water and ischemic heart disease, diabetes mellitus and colorectal cancer; A population-based study in Israel

BACKGROUND

Drinking water (DW) is an important dietary source of magnesium. Recently, Israel has increased its use of desalinated seawater (DSW) as DW country-wide. Its negligible magnesium content, however, raises concern that consumption of DSW may be associated with hypomagnesemia and increase the risk of ischemic heart disease (IHD), diabetes mellitus (DM), and colorectal cancer (CRC).

OBJECTIVES

We tested whether there was a change in incidence of negative health outcomes (IHD, DM, and CRC) following the introduction of DSW supply in a population-based ecologic study in Israel.

METHODS

A historical prospective analysis was applied to members aged 25-76 during 2004-2013 of Clalit Health Services (Clalit), the largest healthcare provider in Israel, using its electronic medical record database. Multivariable analyses were adjusted for age, sex, socioeconomic status, smoking status, and body mass index.

RESULTS

An increased odds ratio was found for IHD (0.96, 95% CI 0.93-0.99 at baseline and 1.06, 95% CI 1.02-1.11 at the end of the follow-up period), but no time trend was observed.

CONCLUSIONS

We found that the risk for IHD increased during the study period. The risks for DM and CRC were unchanged. Long term studies are needed for assessing the risk for CRC due to the long latency. The higher risk for IHD has practical public health implications and raise the need to add magnesium to DSW.

Toxicities Associated with Cisplatin-Based Chemotherapy and Radiotherapy in Long-Term Testicular Cancer Survivors

Testicular cancer has become the paradigm of adult-onset cancer survivorship, due to the young age at diagnosis and 10-year relative survival of 95%. This clinical review presents the current status of various treatment-related complications experienced by long-term testicular cancer survivors (TCS) free of disease for 5 or more years after primary treatment. Cardiovascular disease and second malignant neoplasms represent the most common potentially life-threatening late effects. Other long-term adverse outcomes include neuro- and ototoxicity, pulmonary complications, nephrotoxicity, hypogonadism, infertility, and avascular necrosis. Future research efforts should focus on delineation of the genetic underpinning of these long-term toxicities to understand their biologic basis and etiopathogenetic pathways, with the goal of developing targeted prevention and intervention strategies to optimize risk-based care and minimize chronic morbidities. In the interim, health care providers should advise TCS to adhere to national guidelines for the management of cardiovascular disease risk factors, as well as to adopt behaviors consistent with a healthy lifestyle, including smoking cessation, a balanced diet, and a moderate to vigorous intensity exercise program. TCS should also follow national guidelines for cancer screening as currently applied to the general population.

Predictors of sudden cardiac death in atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

We previously reported that incident atrial fibrillation (AF) is associated with an increased risk of sudden cardiac death (SCD) in the general population. We now aimed to identify predictors of SCD in persons with AF from the Atherosclerosis Risk in Communities (ARIC) study, a community-based cohort study. We included all participants who attended visit 1 (1987-89) and had no prior AF (n = 14,836). Incident AF was identified from study electrocardiograms and hospitalization discharge codes through 2012. SCD was physician-adjudicated. We used cause-specific Cox proportional hazards models, followed by stepwise selection (backwards elimination, removing all variables with p>0.10) to identify predictors of SCD in participants with AF. AF occurred in 2321 (15.6%) participants (age 45-64 years, 58% male, 18% black). Over a median of 3.3 years, SCD occurred in 110 of those with AF (4.7%). Predictors of SCD in AF included higher age, body mass index (BMI), coronary heart disease, hypertension, diabetes, current smoker, left ventricular hypertrophy, increased heart rate, and decreased albumin. Predictors associated only with SCD and not other cardiovascular (CV) death included increased BMI (HR per 5-unit increase, 1.15, 95% CI, 0.97-1.36, p = 0.10), increased heart rate (HR per SD increase, 1.18, 95% CI 0.99-1.41, p = 0.07), and low albumin (HR per SD decrease 1.23, 95% CI 1.02-1.48, p = 0.03). In the ARIC study, predictors of SCD in AF that are not associated with non-sudden CV death included increased BMI, increased heart rate, and low albumin. Further research to confirm these findings in larger community-based cohorts and to elucidate the underlying mechanisms to facilitate prevention is warranted.

Serum magnesium concentrations and all-cause, cardiovascular, and cancer mortality among U.S. adults: Results from the NHANES I Epidemiologic Follow-up Study

BACKGROUND

Few studies have examined the associations of serum magnesium (Mg) concentrations with total and cause-specific mortality in a nationally representative sample of US adults. We investigate the dose-response relationships of baseline serum Mg concentrations with risk of mortalities in a large, nationally representative sample of US adults.

METHODS

We analyzed prospective data of 14,353 participants aged 25-74 years with measures of serum Mg concentrations at baseline (1971-1975) from the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study (NHEFS). Mortality data was linked through December 31, 2011. We estimated the mortality hazard ratios (HRs), for participants within serum Mg categories of <0.7, 0.7-0.74, 0.75-0.79, 0.8-0.89 (referent), 0.9-0.94, 0.95-0.99, and ≥1.0 mmol/L using weighted multivariate-adjusted Cox proportional hazards models.

RESULTS

During a median follow-up of 28.6 years, 9012 deaths occurred, including 3959 CVD deaths, 1923 cancer deaths, and 708 stroke deaths. The multivariate-adjusted HRs (95% CIs) of all-cause mortality across increasing categories of Mg were 1.34 (1.02, 1.77), 0.94 (0.75, 1.18), 1.08 (0.97, 1.19), 1.00 (referent), 1.05 (0.95, 1.16), 0.96 (0.79, 1.15), and 0.98 (0.76, 1.26). Similar trends were observed for cancer (HRs for serum Mg < 0.7: 1.39, 95% CI: 0.83, 2.32) and CVD mortality (HRs for serum Mg < 0.7: 1.28, 95% CI: 0.81, 2.02) but were not statistically significant. An elevated risk for stroke mortality was observed among participants with serum Mg < 0.70 mmol/L (HR: 2.55, 95% CI: 1.18, 5.48).

CONCLUSIONS

Very low serum Mg concentrations were significantly associated with an increased risk of all-cause mortality in US adults.

Magnesium Counteracts Vascular Calcification: Passive Interference or Active Modulation?

Over the last decade, an increasing number of studies report a close relationship between serum magnesium concentration and cardiovascular disease risk in the general population. In end-stage renal disease, an association was found between serum magnesium and survival. Hypomagnesemia was identified as a strong predictor for cardiovascular disease in these patients. A substantial body of in vitro and in vivo studies has identified a protective role for magnesium in vascular calcification. However, the precise mechanisms and its contribution to cardiovascular protection remain unclear. There are currently 2 leading hypotheses: first, magnesium may bind phosphate and delay calcium phosphate crystal growth in the circulation, thereby passively interfering with calcium phosphate deposition in the vessel wall. Second, magnesium may regulate vascular smooth muscle cell transdifferentiation toward an osteogenic phenotype by active cellular modulation of factors associated with calcification. Here, the data supporting these major hypotheses are reviewed. The literature supports both a passive inorganic phosphate-buffering role reducing hydroxyapatite formation and an active cell-mediated role, directly targeting vascular smooth muscle transdifferentiation. However, current evidence relies on basic experimental designs that are often insufficient to delineate the underlying mechanisms. The field requires more advanced experimental design, including determination of intracellular magnesium concentrations and the identification of the molecular players that regulate magnesium concentrations in vascular smooth muscle cells.

Serum Magnesium Concentrations in the Canadian Population and Associations with Diabetes, Glycemic Regulation, and Insulin Resistance

Total serum magnesium (Mg) concentration (SMC) is commonly used to assess Mg status. This study reports current SMCs of Canadians and their associations with demographic factors, diabetes, and measures of glycemic control and insulin resistance using results from the Canadian Health Measures Survey cycle 3 (2012-2013). Associations were examined in adults aged 20-79 years using linear mixed models. Mean SMCs and percentile distributions for 11 sex-age groups between 3 and 79 years (n = 5561) are reported. SMCs were normally distributed and differences (p < 0.05) among sex and age groups were small. Between 9.5% and 16.6% of adult sex-age groups had a SMC below the lower cut-off of a population-based reference interval (0.75-0.955 mmol·L^-1) established in the United States population as part of the NHANES I conducted in 1971-1974. Having diabetes was associated with 0.04 to 0.07 mmol·L^-1 lower SMC compared to not having diabetes in the various models. Body mass index, glycated hemoglobin, serum glucose and insulin concentrations, and homeostatic model assessment of insulin resistance were negatively associated with SMC. This is the first study to report SMCs in a nationally representative sample of the Canadian population. A substantial proportion of Canadians are hypomagnesaemic in relation to a population-based reference interval, and SMC was negatively associated with diabetes and indices of glycemic control and insulin resistance.

Responses to romidepsin by line of therapy in patients with relapsed or refractory peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of aggressive non-Hodgkin lymphomas typically associated with poor prognosis. Most patients with PTCL receive chemotherapy as first-line treatment, but many experience rapid relapse. For patients with relapsed/refractory PTCL, responses to treatment and long-term outcomes tend to worsen with increasing lines of therapy. Romidepsin is a potent class I histone deacetylase inhibitor approved by the US Food and Drug Administration for the treatment of PTCL in patients who have received ≥1 prior therapy. A pivotal phase 2 trial of romidepsin in patients with relapsed/refractory PTCL demonstrated an objective response rate of 25% (33/130), including 15% with confirmed/unconfirmed complete response, and a median duration of response of 28 months. In the analysis presented herein, romidepsin was shown to have similar responses and long-term outcomes in patients with 1, 2, and ≥3 prior lines of treatment, including in patients with disease refractory to the last prior therapy. Although adverse events increased with increasing lines of treatment, the rate of dose modifications and discontinuations due to adverse events was not significantly different. These data support the use of romidepsin as salvage treatment for PTCL irrespective of the number of prior therapies.

Perspective: The Case for an Evidence-Based Reference Interval for Serum Magnesium: The Time Has Come

The 2015 Dietary Guidelines Advisory Committee indicated that magnesium was a shortfall nutrient that was underconsumed relative to the Estimated Average Requirement (EAR) for many Americans. Approximately 50% of Americans consume less than the EAR for magnesium, and some age groups consume substantially less. A growing body of literature from animal, epidemiologic, and clinical studies has demonstrated a varied pathologic role for magnesium deficiency that includes electrolyte, neurologic, musculoskeletal, and inflammatory disorders; osteoporosis; hypertension; cardiovascular diseases; metabolic syndrome; and diabetes. Studies have also demonstrated that magnesium deficiency is associated with several chronic diseases and that a reduced risk of these diseases is observed with higher magnesium intake or supplementation. Subclinical magnesium deficiency can exist despite the presentation of a normal status as defined within the current serum magnesium reference interval of 0.75-0.95 mmol/L. This reference interval was derived from data from NHANES I (1974), which was based on the distribution of serum magnesium in a normal population rather than clinical outcomes. What is needed is an evidenced-based serum magnesium reference interval that reflects optimal health and the current food environment and population. We present herein data from an array of scientific studies to support the perspective that subclinical deficiencies in magnesium exist, that they contribute to several chronic diseases, and that adopting a revised serum magnesium reference interval would improve clinical care and public health.

Serum Potassium, Mortality, and Kidney Outcomes in the Atherosclerosis Risk in Communities Study

OBJECTIVES

To investigate the association between serum potassium, mortality, and kidney outcomes in the general population and whether potassium-altering medications modify these associations.

PATIENTS AND METHODS

We studied 15,539 adults in the Atherosclerosis Risk in Communities Study. Cox proportional hazard regression was used to investigate the association of serum potassium at baseline (1987-1989), evaluated categorically (hypokalemia, <3.5 mmol/L; normokalemia, ≥3.5 and <5.5 mmol/L; hyperkalemia, ≥5.5 mmol/L) and continuously using linear spline terms (knots at 3.5 and 5.5 mmol/L), with mortality, sudden cardiac death, incident chronic kidney disease, and end-stage renal disease. The end date of follow-up for all outcomes was December 31, 2012. We also evaluated whether classes of potassium-altering medications modified the association between serum potassium and adverse outcomes.

RESULTS

Overall, 413 (2.7%) of the participants had hypokalemia and 321 (2.1%) had hyperkalemia. In a fully adjusted model, hyperkalemia was significantly associated with mortality (hazard ratio, 1.24; 95% CI, 1.04-1.49) but not sudden cardiac death, chronic kidney disease, or end-stage renal disease. Hypokalemia as a categorical variable was not associated with any outcome; however, associations of hypokalemia with all-cause mortality and kidney outcomes were observed among those who were not taking potassium-wasting diuretics (all P for interaction, <.001).

CONCLUSIONS

Higher values of serum potassium were associated with a higher risk of mortality in the general population. Lower levels of potassium were associated with adverse kidney outcomes and mortality among participants not taking potassium-wasting diuretics.

Kidney function and sudden cardiac death in the community: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Individuals with chronic kidney disease, particularly those requiring dialysis, are at high risk of sudden cardiac death (SCD). However, comprehensive data for the full spectrum of kidney function and SCD risk in the community are sparse. Furthermore, newly developed equations for estimated glomerular filtration rate (eGFR) and novel filtration markers might add further insight to the role of kidney function in SCD.

METHODS

We investigated the associations of baseline eGFRs using serum creatinine, cystatin C, or both (eGFRcr, eGFRcys, and eGFRcr-cys); cystatin C itself; and β2-microglobulin (B2M) with SCD (205 cases through 2001) among 13,070 black and white ARIC participants at baseline during 1990-1992 using Cox regression models accounting for potential confounders.

RESULTS

Low eGFR was independently associated with SCD risk: for example, hazard ratio for eGFR <45 versus ≥90mL/(min 1.73m(2)) was 3.71 (95% CI 1.74-7.90) with eGFRcr, 5.40 (2.97-9.83) with eGFRcr-cys, and 5.24 (3.01-9.11) with eGFRcys. When eGFRcr and eGFRcys were included together in a single model, the association was only significant for eGFRcys. When three eGFRs, cystatin C, and B2M were divided into quartiles, B2M demonstrated the strongest association with SCD (hazard ratio for fourth quartile vs first quartile 3.48 (2.03-5.96) vs ≤2.7 for the other kidney markers).

CONCLUSIONS

Kidney function was independently and robustly associated with SCD in the community, particularly when cystatin C or B2M was used. These results suggest the potential value of kidney function as a risk factor for SCD and the advantage of novel filtration markers over eGFRcr in this context.

Development and Validation of a Sudden Cardiac Death Prediction Model for the General Population

BACKGROUND

Most sudden cardiac death (SCD) events occur in the general population among persons who do not have any prior history of clinical heart disease. We sought to develop a predictive model of SCD among US adults.

METHODS

We evaluated a series of demographic, clinical, laboratory, electrocardiographic, and echocardiographic measures in participants in the ARIC study (Atherosclerosis Risk in Communities) (n=13 677) and the CHS (Cardiovascular Health Study) (n=4207) who were free of baseline cardiovascular disease. Our initial objective was to derive a SCD prediction model using the ARIC cohort and validate it in CHS. Independent risk factors for SCD were first identified in the ARIC cohort to derive a 10-year risk model of SCD. We compared the prediction of SCD with non-SCD and all-cause mortality in both the derivation and validation cohorts. Furthermore, we evaluated whether the SCD prediction equation was better at predicting SCD than the 2013 American College of Cardiology/American Heart Association Cardiovascular Disease Pooled Cohort risk equation.

RESULTS

There were a total of 345 adjudicated SCD events in our analyses, and the 12 independent risk factors in the ARIC study included age, male sex, black race, current smoking, systolic blood pressure, use of antihypertensive medication, diabetes mellitus, serum potassium, serum albumin, high-density lipoprotein, estimated glomerular filtration rate, and QTc interval. During a 10-year follow-up period, a model combining these risk factors showed good to excellent discrimination for SCD risk (c-statistic 0.820 in ARIC and 0.745 in CHS). The SCD prediction model was slightly better in predicting SCD than the 2013 American College of Cardiology/American Heart Association Pooled Cohort risk equations (c-statistic 0.808 in ARIC and 0.743 in CHS). Only the SCD prediction model, however, demonstrated similar and accurate prediction for SCD using both the original, uncalibrated score and the recalibrated equation. Finally, in the echocardiographic subcohort, a left ventricular ejection fraction <50% was present in only 1.1% of participants and did not enhance SCD prediction.

CONCLUSIONS

Our study is the first to derive and validate a generalizable risk score that provides well-calibrated, absolute risk estimates across different risk strata in an adult population of white and black participants without a clinical diagnosis of cardiovascular disease.

Echocardiographic Predictors of Sudden Cardiac Death: The Atherosclerosis Risk in Communities Study and Cardiovascular Health Study

BACKGROUND

This study assessed the echocardiographic predictors of sudden cardiac death (SCD) within 2 population-based cohorts.

METHODS AND RESULTS

Echocardiograms were obtained on 2383 participants (1993-1995) from the ARIC study (Atherosclerosis Risk in Communities; 100% black) and 5366 participants (1987-1989 and 1994-1995) from the CHS (Cardiovascular Health Study). The main outcome was physician-adjudicated SCD. We used Cox proportional-hazards models with incident coronary heart disease and heart failure as time-dependent covariates to assess the association between echocardiographic variables and SCD, adjusting for Framingham risk score variables, coronary heart disease, and renal function. Cohort-specific results were meta-analyzed. During a median follow-up of 7.3 and 13.1 years, 44 ARIC study participants and 275 CHS participants had SCD, respectively. In the meta-analyzed results, the adjusted hazard ratios (95% confidence intervals) for predictors of SCD were 3.07 (2.29-4.11) for reduced left ventricular ejection fraction; 1.85 (1.36-2.52) for mitral annular calcification; 1.64 (1.07-2.51) for mitral E/A >1.5, and 1.52 (1.14-2.02) for mitral E/A <0.7 (versus mitral E/A 0.7-1.5); 1.30 (1.15-1.48) per 1 SD increase in left ventricular mass; and 1.15 (1.02-1.30) per 1 SD increase in left atrial diameter. A receiver-operating characteristic model for prediction of SCD using Framingham risk score variables had a C statistic of 0.61 for ARIC study and 0.67 for CHS; the full multivariable model including all echocardiographic variables had a C statistic of 0.76 for ARIC study and 0.74 for CHS.

CONCLUSIONS

In addition to reduced left ventricular ejection fraction, we identified other echocardiographic-derived variables predictive for SCD that provided incremental value compared with clinical risk factors.

Romidepsin for the treatment of relapsed/refractory cutaneous T-cell lymphoma (mycosis fungoides/Sézary syndrome): Use in a community setting

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of rare non-Hodgkin lymphomas that arise in the skin. In advanced stages, CTCL becomes systemic and is associated with poor prognosis. Diagnosis of CTCL and treatment of early-stage disease with topical therapies often occurs under the care of a dermatologist. Community oncologists see few patients with CTCL due to direct referrals from dermatologists to academic or lymphoma specialty centers. However, some patients will continue to be managed in a community setting. Currently there is no evidence-based stepwise algorithm for treatment of patients with CTCL, and guidelines suggest a wide range of systemic therapies, including biologics, targeted agents, and more traditional chemotherapies. To provide optimal care in a community setting, oncologists must become familiar with newer nonchemotherapeutic treatment options. This review highlights romidepsin, a histone deacetylase inhibitor approved for the treatment of patients with CTCL who have received ≥1 prior systemic therapy.

Desalinated seawater supply and all-cause mortality in hospitalized acute myocardial infarction patients from the Acute Coronary Syndrome Israeli Survey 2002-2013

BACKGROUND

Consuming desalinated seawater (DSW) as drinking water (DW) may reduce magnesium in water intake causing hypomagnesemia and adverse cardiovascular effects.

METHODS

We evaluated 30-day and 1-year all-cause mortality of acute myocardial infarction (AMI) patients enrolled in the biannual Acute Coronary Syndrome Israeli Survey (ACSIS) during 2002-2013. Patients (n=4678) were divided into 2 groups: those living in regions supplied by DSW (n=1600, 34.2%) and non-DSW (n=3078, 65.8%). Data were compared between an early period [2002-2006 surveys (n=2531) - before desalination] and a late period [2008-2013 surveys (n=2147) - during desalination].

RESULTS

Thirty-day all-cause-mortality was significantly higher in the late period in patients from the DSW regions compared with those from the non-DSW regions (HR=2.35 CI 95% 1.33-4.15, P<0.001) while in the early period there was no significant difference (HR=1.37 CI 95% 0.9-2, P=0.14). Likewise, there was a significantly higher 1-year all-cause mortality in the late period in patients from DSW regions compared with those from the non-DSW regions (HR=1.87 CI 95% 1.32-2.63, P<0.0001), while in the early period there was no significant difference (HR=1.17 CI 95% 0.9-1.5, P=0.22). Admission serum magnesium level (M±SD) in the DSW regions (n=130) was 1.94±0.24mg/dL compared with 2.08±0.27mg/dL in 81 patients in the non-DSW (P<0.0001).

CONCLUSIONS

Higher 30-day and 1-year all-cause mortality in AMI patients, found in the DSW regions may be attributed to reduced magnesium intake secondary to DSW consumption.

Magnesium: Nutrition and Homoeostasis

The essential mineral magnesium is involved in numerous physiological processes. Recommended dietary intake is often not met and a low magnesium status increases the risk for various diseases. Magnesium status is regulated by several magnesium transport systems either in cellular or paracellular pathways. Numerous drugs either interfere with magnesium absorption in the intestines or the reabsorption from primary urine in the kidney. Low magnesium status has been identified as a significant risk factor for several diseases, including type-2 diabetes, cardiovascular diseases, arrhythmias, as well as general muscular and neurological problems. Therefore, an adequate magnesium supply would be of special benefit to our overall health.

Romidepsin for the treatment of relapsed/refractory peripheral T cell lymphoma: prolonged stable disease provides clinical benefits for patients in the pivotal trial

BACKGROUND

Achievement of durable responses in patients with relapsed/refractory peripheral T cell lymphoma (PTCL) is challenging with current therapies, and there are few data regarding the potential benefits of continuing treatment in patients with the best response of stable disease (SD). Histone deacetylase inhibitors are a novel class of drugs with activity in T cell malignancies. Romidepsin was approved by the US Food and Drug Administration for the treatment of relapsed/refractory PTCL based on a pivotal trial demonstrating an objective response rate of 25% (33/130), including 15% with confirmed/unconfirmed complete response and a median duration of response of 28 months. Our objective was to further study the clinical benefits of romidepsin in patients that had the best response of SD.

METHODS

Patients with PTCL relapsed/refractory to ≥1 prior therapy were treated with the approved dose of 14 mg/m(2) romidepsin on days 1, 8, and 15 of six 28-day cycles; patients with SD or response after cycle 6 were allowed to continue on study until progression. By protocol amendment, patients treated for ≥12 cycles could receive maintenance dosing twice per cycle; after cycle 24, dosing could be further reduced to once per cycle in those who had received maintenance dosing for ≥6 months.

RESULTS

Of the 32 patients (25%) with the best response of SD, 22 had SD for ≥90 days (SD90; cycle 4 response assessment). The longest SD was >3 years in a patient who received maintenance dosing of 14 mg/m(2) on days 1 and 15 beginning in cycle 13. Patients with the best response of SD90 or partial response achieved similar overall and progression-free survival. Prolonged dosing of romidepsin was well tolerated.

CONCLUSIONS

We concluded that patients who achieve SD may consider continuing treatment because the clinical benefits of romidepsin may extend beyond objective responses.

TRIAL REGISTRATION

NCT00426764.

Serum Magnesium and the Risk of Death From Coronary Heart Disease and Sudden Cardiac Death

BACKGROUND

Low serum magnesium has been implicated in cardiovascular mortality, but results are conflicting and the pathway is unclear. We studied the association of serum magnesium with coronary heart disease (CHD) mortality and sudden cardiac death (SCD) within the prospective population-based Rotterdam Study, with adjudicated end points and long-term follow-up.

METHODS AND RESULTS

Nine-thousand eight-hundred and twenty participants (mean age 65.1 years, 56.8% female) were included with a median follow-up of 8.7 years. We used multivariable Cox proportional hazard models and found that a 0.1 mmol/L increase in serum magnesium level was associated with a lower risk for CHD mortality (hazard ratio: 0.82, 95% CI 0.70-0.96). Furthermore, we divided serum magnesium in quartiles, with the second and third quartile combined as reference group (0.81-0.88 mmol/L). Low serum magnesium (≤0.80 mmol/L) was associated with an increased risk of CHD mortality (N=431, hazard ratio: 1.36, 95% CI 1.09-1.69) and SCD (N=217, hazard ratio: 1.54, 95% CI 1.12-2.11). Low serum magnesium was associated with accelerated subclinical atherosclerosis (expressed as increased carotid intima-media thickness: +0.013 mm, 95% CI 0.005-0.020) and increased QT-interval, mainly through an effect on heart rate (RR-interval: -7.1 ms, 95% CI -13.5 to -0.8). Additional adjustments for carotid intima-media thickness and heart rate did not change the associations with CHD mortality and SCD.

CONCLUSIONS

Low serum magnesium is associated with an increased risk of CHD mortality and SCD. Although low magnesium was associated with both carotid intima-media thickness and heart rate, this did not explain the relationship between serum magnesium and CHD mortality or SCD. Future studies should focus on why magnesium associates with CHD mortality and SCD and whether intervention reduces these risks.