Publications

BACKGROUND

To our knowledge, the risk of sudden cardiac death (SCD) and the assessment of risk factors in prediction models have not been evaluated in women with coronary artery disease (CAD). We sought to evaluate the incidence of SCD as well as its risk factors and their predictive accuracy among a population of women with CAD.

METHODS

The Heart and Estrogen/progestin Replacement Study evaluated the effects of hormone replacement therapy on cardiovascular events among 2763 postmenopausal women with CAD. Sudden cardiac death was defined as death resulting from a cardiac origin that occurred within 1 hour of symptom onset. The associations between candidate predictor variables and SCD were evaluated in a Cox proportional hazards model. The C-index was used to compare the predictive value of the clinical risk factors with left ventricular ejection fraction (LVEF) alone and in combination. The net reclassification improvement was also computed.

RESULTS

Over a mean follow-up of 6.8 years, SCD comprised 136 of the 254 cardiac deaths. The annual SCD event rate was 0.79% (95% confidence interval, 0.67-0.94). The following variables were independently associated with SCD in the multivariate model: myocardial infarction, heart failure, an estimated glomerular filtration rate of less than 40 mL/min/1.73 m(2), atrial fibrillation, physical inactivity, and diabetes. The incidences of SCD among women with 0 (n = 683), 1 (n = 1224), 2 (n = 610), and 3 plus (n = 246) risk factors at baseline were 0.3%, 0.5%, 1.2%, and 2.9% per year, respectively. The combination of clinical risk factors and LVEF (C-index, 0.681) were better predictors of SCD than LVEF alone (C-index, 0.600) and resulted in a net reclassification improvement of 0.20 (P < .001).

CONCLUSIONS

Sudden cardiac death comprised the majority of cardiac deaths among postmenopausal women with CAD. Independent predictors of SCD, including myocardial infarction, congestive heart failure, an estimated glomerular filtration rate of less than 40 mL/min/1.73 m(2), atrial fibrillation, physical inactivity, and diabetes, improved SCD prediction when they were considered in addition to LVEF.

Concentric left ventricular (LV) hypertrophy develops in response to a chronically increased LV afterload and is associated with increased cardiovascular events. Although the progression to systolic and diastolic heart failure is a known consequence of LV hypertrophy, few data are available on the frequency of deterioration to systolic dysfunction in patients with LV hypertrophy who originally had a normal LV ejection fraction. We evaluated the baseline and follow-up characteristics in 1,024 patients with concentric LV hypertrophy and a normal ejection fraction who had paired echocardiograms that were separated by ≥1 year. Systolic dysfunction occurred in 134 patients (13%) after a mean follow-up of 33 ± 24 months. The most common associated variable was interval myocardial infarction, which occurred in 43% of patients. Other risk factors for developing LV systolic dysfunction included QRS prolongation (>120 ms) and elevated follow-up arterial impedance defined as a value >4.0 mm Hg/ml/m(2). Patients with either a prolonged QRS interval or an elevated follow-up arterial impedance had twice the likelihood of developing LV systolic dysfunction, and, if both factors were present, there was a greater than fourfold increased risk of developing systolic dysfunction. Blood pressure measurements alone did not adequately reflect an elevated arterial impedance. In conclusion, 13% of patients with a normal ejection fraction and concentric LV hypertrophy progress to systolic dysfunction during approximately 3 years of follow-up. The risk factors for loss of function were interval myocardial infarction, prolonged QRS, and chronically elevated arterial impedance.

BACKGROUND AND OBJECTIVES

Awareness of chronic kidney disease (CKD) among providers and patients is low. Whether clinical cues prompt recognition of CKD is unknown. We examined whether markers of kidney disease that should trigger CKD recognition among providers are associated with higher individual CKD awareness.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

CKD awareness was assessed in 1852 adults with an estimated GFR <60 ml/min per 1.73 m(2) using 1999 to 2008 National Health and Nutrition Examination Survey data. CKD awareness was a "yes" answer to "Have you ever been told you have weak or failing kidneys?" Participants were grouped by distribution of the following abnormal markers of CKD: hyperkalemia, acidosis, hyperphosphatemia, elevated blood urea nitrogen, anemia, albuminuria, and uncontrolled hypertension. Odds of CKD awareness associated with each abnormal marker and groupings of markers were estimated by multivariable logistic regression.

RESULTS

Among individuals with kidney disease, only those with albuminuria had greater odds of CKD awareness (adjusted odds ratio, 4.0, P < 0.01) than those without. Odds of CKD awareness increased with each additional manifested clinical marker of CKD (adjusted odds ratio, 1.3, P = 0.05). Nonetheless, 90% of individuals with two to four markers of CKD and 84% of individuals with ≥5 markers of CKD were unaware of their disease.

CONCLUSIONS

Although individuals who manifest many markers of kidney dysfunction are more likely to be aware of their CKD, their CKD awareness remains low. A better understanding of mechanisms of awareness is required to facilitate earlier detection of CKD and implement therapy to minimize associated complications.

We have reported that pyrroloquinoline quinone (PQQ) improves reproduction, neonatal development, and mitochondrial function in animals by mechanisms that involve mitochondrial related cell signaling pathways. To extend these observations, the influence of PQQ on energy and lipid relationships and apparent protection against ischemia reperfusion injury are described herein. Sprague-Dawley rats were fed a nutritionally complete diet with PQQ added at either 0 (PQQ-) or 2 mg PQQ/Kg diet (PQQ+). Measurements included: 1) serum glucose and insulin, 2) total energy expenditure per metabolic body size (Wt(3/4)), 3) respiratory quotients (in the fed and fasted states), 4) changes in plasma lipids, 5) the relative mitochondrial amount in liver and heart, and 6) indices related to cardiac ischemia. For the latter, rats (PQQ- or PQQ+) were subjected to left anterior descending occlusions followed by 2 h of reperfusion to determine PQQ's influence on infarct size and myocardial tissue levels of malondialdehyde, an indicator of lipid peroxidation. Although no striking differences in serum glucose, insulin, and free fatty acid levels were observed, energy expenditure was lower in PQQ- vs. PQQ+ rats and energy expenditure (fed state) was correlated with the hepatic mitochondrial content. Elevations in plasma di- and triacylglyceride and β-hydroxybutryic acid concentrations were also observed in PQQ- rats vs. PQQ+ rats. Moreover, PQQ administration (i.p. at 4.5 mg/kg BW for 3 days) resulted in a greater than 2-fold decrease in plasma triglycerides during a 6-hour fast than saline administration in a rat model of type 2 diabetes. Cardiac injury resulting from ischemia/reperfusion was more pronounced in PQQ- rats than in PQQ+ rats. Collectively, these data demonstrate that PQQ deficiency impacts a number of parameters related to normal mitochondrial function.