Do lipids,blood pressure,diabetes, and smoking confer equal risk of myocardial infarction in women as in men? The Reykjavik Study

BACKGROUND: Studies on coronary risk factors in men and women are mainly based on mortality data and few compare results of both sexes with consistent study design and diagnostic criteria. This study assesses the major risk factors for coronary events in men and women from the Reykjavik Study. DESIGN: Within a prospective, population-based cohort study individuals without history of myocardial infarction were identified and the relative risk of baseline variables was assessed in relation to verified myocardial infarction or coronary death during follow-up. METHODS: Of the 9681 women and 8888 men who attended risk assessment from 1967-1991, with follow-up period of up to 28 years, 706 women and 1700 men suffered a non-fatal myocardial infarction or coronary death. RESULTS: Serum cholesterol was a significant risk factor for both sexes, with hazard ratios (HR) decreasing with age. Systolic blood pressure was a stronger risk factor for women as was ECG-confirmed left ventricular hypertrophy (women HR 2.89, 95% confidence interval [CI] 1.67-5.01; men HR 1.11 [CI 0.86-1.43]). Fasting blood glucose > or =6.7 mmol/L identified significantly higher risk for women (HR 2.65) than men (HR 2.08) as did self-reported diabetes. Triglyceride risk was significantly higher for women and decreased significantly with age. Smoking increased risk two- to five-fold, increasing with dose, for women, which was significantly higher than the doubling in risk for men. CONCLUSIONS: This large study of the major risk factors compared between the sexes demonstrates similar relative risk of myocardial infarction associated with cholesterol for both sexes, however, the relative risk is higher in women for many other risk factors such as smoking, diabetes, elevated triglycerides and left ventricular hypertrophy.     

CT for assessing ventricular remodeling: Is it ready for prime time?

Reliable assessment of left ventricular size and systolic function has important prognostic and therapeutic implications for patients with heart disease. CT technology is advancing rapidly and can be used for noninvasive assessment of the coronary anatomy. Without additional radiation or contrast, the already acquired image data set can be used for analysis of left ventricular size, mass, and systolic function. In comparison with other noninvasive modalities, multidetector CT has superior spatial resolution but temporal resolution has suffered. Recent advances, including multisegment reconstruction and dual-source scanning, have improved the temporal resolution substantially. MRI is the current gold standard for assessing the left ventricle. Many small comparative studies suggest that CT has good agreement with MRI and that it could potentially replace MRI in some patients, especially those with internal cardiac devices. The use of CT to assess ventricular remodeling is limited by the use of contrast and radiation, but its widespread availability, ease of use, and improved temporal resolution suggest that multidetector CT will have expansive use in the future.     

Mediation Analysis of Aortic Stiffness and Renal Microvascular Function

Aortic stiffening, assessed by carotid-femoral pulse wave velocity, is associated with CKD. Transmission of excessive flow pulsatility into the low-impedance renal microvasculature may mediate this association. However, direct analyses of macrovascular–microvascular relations in the kidney are limited. Using arterial tonometry, iohexol clearance, and magnetic resonance imaging, we related arterial stiffness, GFR, urinary albumin excretion, and potential mediators, including renal artery pulsatility index, renal vascular resistance, and arterial volume in the cortex, in 367 older adults (ages 72–92 years) participating in the Age, Gene/Environment Susceptibility-Reykjavik Study. In a model adjusted for age, sex, heart rate, and body size, aortic stiffness was related to GFR (Slope of regression B=−2.28±0.85 ml/min per SD, P=0.008) but not urine albumin (P=0.09). After accounting for pulsatility index, the relation between aortic stiffness and GFR was no longer significant (P=0.10). Mediation analysis showed that 34% of the relation between aortic stiffness and GFR was mediated by pulsatility index (95% confidence interval of indirect effect, −1.35 to −0.29). An additional 20% or 36% of the relation was mediated by lower arterial volume in the cortex or higher renal vascular resistance, respectively, when offered as mediators downstream from higher pulsatility index (95% confidence interval of indirect effect including arterial volume in the cortex, −2.22 to −0.40; 95% confidence interval of indirect effect including renal vascular resistance, −2.51 to −0.76). These analyses provide the first evidence that aortic stiffness may contribute to lower GFR by transferring excessive flow pulsatility into the susceptible renal microvasculature, leading to dynamic constriction or vessel loss.     

Assessment of incident spine and hip fractures in women and men using finite element analysis of CT scans

Finite element analysis of computed tomography (CT) scans provides noninvasive estimates of bone strength at the spine and hip. To further validate such estimates clinically, we performed a 5‐year case‐control study of 1110 women and men over age 65 years from the AGES‐Reykjavik cohort (case = incident spine or hip fracture; control = no incident spine or hip fracture). From the baseline CT scans, we measured femoral and vertebral strength, as well as bone mineral density (BMD) at the hip (areal BMD only) and lumbar spine (trabecular volumetric BMD only). We found that for incident radiographically confirmed spine fractures (n = 167), the age‐adjusted odds ratio for vertebral strength was significant for women (2.8, 95% confidence interval [CI] 1.8 to 4.3) and men (2.2, 95% CI 1.5 to 3.2) and for men remained significant (p = 0.01) independent of vertebral trabecular volumetric BMD. For incident hip fractures (n = 171), the age‐adjusted odds ratio for femoral strength was significant for women (4.2, 95% CI 2.6 to 6.9) and men (3.5, 95% CI 2.3 to 5.3) and remained significant after adjusting for femoral neck areal BMD in women and for total hip areal BMD in both sexes; fracture classification improved for women by combining femoral strength with femoral neck areal BMD (p = 0.002). For both sexes, the probabilities of spine and hip fractures were similarly high at the BMD‐based interventional thresholds for osteoporosis and at corresponding preestablished thresholds for “fragile bone strength” (spine: women ≤ 4500 N, men ≤ 6500 N; hip: women ≤ 3000 N, men ≤ 3500 N). Because it is well established that individuals over age 65 years who have osteoporosis at the hip or spine by BMD criteria should be considered at high risk of fracture, these results indicate that individuals who have fragile bone strength at the hip or spine should also be considered at high risk of fracture. © 2014 American Society for Bone and Mineral Research.     

The effect of raloxifene on markers of bone turnover in older women living in long-term care facilities

OBJECTIVES: To examine the effect of raloxifene on bone turnover in elderly women. DESIGN: Clinical intervention. SETTING: Long-term care facilities. PARTICIPANTS: Nineteen women completed the study, mean age 85 (range 76-99). INTERVENTION: Raloxifene 60 mg was given daily for 12 weeks. MEASUREMENTS: Markers of bone turnover were plasma C-telopeptides of type I collagen (CTx), urine cross-linked N-telopeptides of type I collagen (NTx) and serum tartrate-resistant acid phosphatase (TRAP 5b), plasma osteocalcin, and serum bone alkaline phosphatase. Other markers were serum 25-OH vitamin D, parathyroid hormone, ionized calcium, and phosphate. Markers were measured at baseline, after calcium and vitamin D had been taken for 6 weeks, after raloxifene had been taken for 12 weeks, and 6 weeks after raloxifene had been stopped. Paired sample t test was used to examine changes in markers at each time point. RESULTS: Plasma CTx decreased on average by 31%, urinary NTx by 35%, plasma osteocalcin by 25%, serum bone alkaline phosphatase by 15% (P<.01), and serum TRAP 5b by 10% (P<.05) on treatment. CONCLUSION: Raloxifene reduces bone turnover in elderly women living in long-term care facilities. The effect of raloxifene on bone turnover is comparable with that seen in younger postmenopausal women.