The occurrence of the alerting response is independent of the method of blood pressure measurement in hypertensive patients

OBJECTIVE

Current guidelines stress the need for more than one measurement of blood pressure in the hypertensive patient. The frequency with which the first blood pressure significantly exceeds subsequent blood pressures (alerting response) is unknown. Participants in a hypertension treatment trial before initiation of therapy were included in post-hoc analyses to investigate the alerting response separately for trained nurse blood pressure measurements with mercury sphygmomanometer and measurements taken by an Omron 705 CP automated device.

BASIC METHODS

A total of 313 participants were included. Each participant had three nurse blood pressure readings before a 24-h automated blood pressure monitoring device was attached, and three Omron measurements at the time the automated blood pressure monitoring device was removed. Alerting response was defined separately for systolic and diastolic measures as a decrease of > or =8 or > or =6 mmHg, respectively, from first measure to the average of the second and third measures.

MAIN RESULTS

An alerting response was observed in 20.4% of nurse-performed blood pressure measurements and 28.4% of Omron measurements. A large range of variation between first blood pressure and average second and third measures was observed, with changes of up to 30 mmHg systolic and 20 mmHg diastolic. The only demographic factor associated with the alerting response was body mass index, with obese patients more likely to exhibit an alerting response (P=0.004) in nurse-measured blood pressure.

CONCLUSIONS

We found the alerting response with both methods of blood pressure measurement; however, it was not consistently observed in the same individuals. This confirms that hypertensive patients require multiple blood pressure measurements.

Relation of arterial stiffness to left ventricular diastolic function and cardiovascular risk prediction in patients > or =65 years of age

There is a paucity of data regarding the relation between the various noninvasive indexes of arterial stiffness and left ventricular diastolic function. In 188 subjects aged > or =65 years (mean 75 +/- 5; 71% men), the concordance and strength of the association between measures of arterial stiffness and left ventricular diastolic function were evaluated. Indexes of arterial stiffness (brachial and aortic pulse pressure [PP], carotid-femoral pulse-wave velocity [PWV], and augmentation pressure [AP]) were measured using applanation tonometry. Diastolic function was classified in terms of instantaneous diastolic function grade and quantitated as left atrial volume, a measure of chronic diastolic burden. Risk for new cardiovascular events was estimated using a validated clinical echocardiographic risk algorithm. Aortic and brachial PP, PWV, and AP were correlated positively with left atrial volume and diastolic function grade. After adjusting for age, gender, and clinical and echocardiographic covariates, 1-SD increases in aortic PP, brachial PP, PWV, and AP were associated with 6%, 6%, 4%, and 4% increases in indexed left atrial volume, respectively. Similarly, 1-SD increases in aortic PP, brachial PP, and AP were associated with 84%, 81%, and 83% increased risk for diastolic dysfunction, respectively (all p <0.04). PWV and aortic and brachial PP were superior to AP in discriminating subjects with the highest risk of having new cardiovascular events (5-year risk >50%; area under receiver-operating characteristic curve 0.67, 0.67, 0.70, and 0.56, respectively; p <0.05). In conclusion, increased arterial stiffness was associated with more severe left ventricular diastolic dysfunction, although the strength of the association varied according to the specific measure used. Aortic PP, brachial PP, and PWV appeared superior to AP in risk discrimination in this elderly cohort.

Two-dimensional echocardiographic methods for assessment of left atrial volume

Left atrial (LA) size is an important predictor of cardiovascular events. Various methods of LA volume assessment exist, but their differences have not been defined. This prospective study included 631 patients (331 men; mean age of 68 +/- 14 years) without a history of atrial arrhythmias, stroke, valvular heart disease, pacemaker implantation, or congenital heart disease. All underwent echocardiography with comprehensive diastolic function assessment and LA volume measurement by 3 commonly used methods: biplane area-length, biplane Simpson's method, and the prolate-ellipsoid method. Mean LA volumes were 39 +/- 14 ml/m2 by the area-length method, 38 +/- 13 ml/m2 by the Simpson's method, and 32 +/- 14 ml/m2 by the prolate-ellipsoid method. In 92% of patients, the prolate measurement was smaller than the 2 biplane methods. Pairwise correlations (r) were 0.98 for area-length versus Simpson's, 0.85 for prolate versus area-length, and 0.86 for prolate versus Simpson's (all p values <0.001). For distinguishing normal (n = 62) from pseudonormal diastolic function (n = 240) using receiver-operating curve analysis, areas under the curves were 0.76, 0.78, and 0.75 for the area-length, Simpson's, and prolate methods, respectively (all p values <0.001, no significant intermethod differences). In conclusion, our findings suggest that there are systematic differences among existing LA volume methods. Biplane area-length and Simpson's methods compare closely, whereas the prolate-ellipsoid method generally yields smaller volumes.

Aortic augmentation index is inversely associated with cardiorespiratory fitness in men without known coronary heart disease

BACKGROUND

We investigated whether the aortic augmentation index (AIx), a measure of arterial wave reflection and stiffness, is associated with cardiorespiratory fitness in men without known coronary heart disease (CHD).

METHODS

Asymptomatic men (n = 201, mean age 51 +/- 9.2 years) referred for a screening exercise electrocardiogram (ECG) underwent applanation tonometry to obtain radial artery pulse waveforms, and an ascending aortic pressure waveform was derived by a transfer function. The AIx is the difference between the first and second systolic peak of the ascending aortic pressure waveform, expressed as a percentage of the pulse pressure. Cardiorespiratory fitness was assessed by maximal oxygen consumption (VO2max mL/min/kg) during a symptom-limited graded exercise test. Multivariable regression analyses were used to identify significant independent determinants of AIx and of VO2 max.

RESULTS

Diabetes was present in 2.5% of subjects, 34.8% had history of smoking, and 29% were hypertensive. Mean (+/- SD) AIx was 19.9% +/- 9.0% and mean VO(2 max) was 33.9 +/- 6.4 mL/min/kg. In a multivariable linear regression model, AIx was positively associated with age, hypertension, and history of smoking and inversely with heart rate, height, and body mass index (BMI). The VO2 max was significantly inversely related to AIx after adjustment for age, heart rate, height, and BMI (r = -0.22, P = .002), after further adjustment for CHD risk factors (total cholesterol, HDL-cholesterol, history of smoking, diabetes, hypertension) (P = .006), and after additional adjustment for behavioral factors (physical activity score, alcohol intake, and percent body fat) (P = .022).

CONCLUSIONS

These findings indicate that AIx, a measure of arterial wave reflection and stiffness, is inversely associated with cardiorespiratory fitness in men without CHD.

Ex vivo hypothermic recirculatory adenoviral gene transfer to the transplanted pig heart

BACKGROUND

To facilitate the application of adenoviral gene therapy in clinical heart transplantation, we developed an ex vivo hypothermic recirculatory adenoviral gene transfer method to the transplanted pig heart.

METHODS

Experimental animals were assigned into three groups; controls, 1x10(8) plaque-forming units (pfu)/ml group and 1x10(9) pfu/ml group. During the 30 min gene transfer perfusion, 200 ml of University of Wisconsin solution containing the adenoviral vector was recirculated through the coronary vessels. The myocardial temperature was maintained below 4 degrees C and the perfusion pressure was adjusted at 50 mmHg.

RESULTS

Cardiac myocyte transduction efficiencies in the 1x10(8) pfu/ml group were 0.04% and 0.07%, whereas transduction efficiencies in the 1x10(9) pfu/ml group were widely distributed from 0.45% to 22.62%. The gene transduction efficiency increased with the virus titer. Additionally, no difference in the transduction efficiency was observed between different segments of the left ventricle. The current gene transfer method at 1x10(9) pfu/ml of adenovirus titer enabled homogeneous gene transduction into the transplanted pig heart up to a maximum of 22.62%.

CONCLUSIONS

This model can be applied to a large isolated heart and will greatly facilitate the investigation of gene therapy in large animal models of heart transplantation.

Left Atrial Volume Predicts the Risk of Atrial Fibrillation After Cardiac Surgery

OBJECTIVES

This study sought to identify preoperative predictors of postoperative atrial fibrillation (POAF) among patients undergoing cardiac surgery.

BACKGROUND

Postoperative atrial fibrillation is frequent after cardiac surgery and is associated with increased morbidity, mortality, prolonged hospital stay, and increased costs. Left atrial volume (LAV), a marker of chronically elevated left ventricular filling pressure, is a predictor of atrial fibrillation (AF) in the nonsurgical setting.

METHODS

A total of 205 patients (mean age 62 +/- 16 years; 35% women) undergoing cardiac surgery were prospectively enrolled. Clinical risk factors were obtained by detailed medical record review and patient interview. Preoperative transthoracic echocardiograms were performed for assessment of LAV, left ventricular ejection fraction, and diastolic function. Follow-up was complete. Detection of POAF was based on documentation of AF episodes by continuous telemetry throughout hospitalization.

RESULTS

Postoperative atrial fibrillation occurred in 84 patients (41.4%) at a median of 1.8 days after cardiac surgery. The LAV was significantly larger in patients in whom AF developed (49 +/- 14 ml/m2 vs. 39 +/- 16 ml/m2, p = 0.0001). Patients with LAV >32 ml/m2 had an almost five-fold increased risk of POAF, independently of age and clinical risk factors (adjusted hazard ratio 4.84, 95% confidence interval 1.93 to 12.17, p = 0.001). Age and LAV were the only independent predictors of POAF. The area under the receiver-operator characteristics curve to predict POAF was 0.729 for LAV and 0.768 for the combination of LAV and age (both p < 0.0001).

CONCLUSIONS

The LAV is a strong and independent predictor of POAF. Risk stratification using LAV and age enables clinicians to identify high-risk patients before cardiac surgery.

Temporal trends in prevalence of diabetes mellitus in a population-based cohort of incident myocardial infarction and impact of diabetes on survival

OBJECTIVE

To determine the temporal trends in prevalence of confirmed diabetes mellitus (DM), time from the date DM criteria were met to myocardial infarction (MI), and impact of DM on survival.

SUBJECTS AND METHODS

A retrospective cohort design was used to identify residents of Olmsted County, Minnesota, with incident MI from 1979 to 1998. The MI cases were characterized according to prevalent DM. Cases with and without DM were followed up for vital status until January 1, 2003.

RESULTS

Of 2171 MI cases, 364 (17%) met criteria for prevalent DM. In the age- and sex-adjusted logistic regression models, the odds of prevalent DM Increased 3% with each Increasing year between 1979 and 1998 (95% confidence Interval [CI], 1%-5%; P=.007). Survival for MI cases with DM was unchanged between 1979-1983 and 1994-1998 (P=.74). For all MI cases, age-, sex-, and DM-adjusted risk of death decreased 3% from 1979 to 1998 (95% CI, 1%-5%) per year for 28-day survival (P=.02) and 2% (95% CI, 1%-3%) per year for 5-year survival (P=.02). There was a significant adverse effect of DM on 5-year survival after MI (age-, sex-, and calendar year-adjusted hazard ratio, 1.70; 95% CI, 1.38-2.09; P<.001). The adverse effect of DM persisted after adjusting for other cardiovascular disease risk factors, MI severity, and reperfusion therapy (hazard ratio, 1.66; 95% CI, 1.34-2.05; P<.001) and was unchanged over time (interaction between DM and calendar year, P=-.63).

CONCLUSION

These data indicate that the prevalence of DM among patients with MI is increasing and that its adverse impact on survival after MI remains unchanged.

Relationship between cardiac output and oxygen consumption during upright cycle exercise in healthy humans

The relationship between cardiac output (CardOut) and oxygen consumption (VO2) during exercise has generally been assumed to be linear. To test this assumption, we studied 72 healthy subjects using a graded, 2-min cycle-ergometry exercise test to maximum while measuring gas exchange continuously and CardOut at the end of each stage, the latter using an open-circuit gas technique. Data for VO2 and CardOut at each stage were fit to a quadratic expression y = a + (b.VO2) + (c.VO2(2)), and statistical significance of the quadratic c term was determined in each subject. Subjects were then divided into two groups: those with statistically significant negative quadratic term ("negative curvature group," n = 25) and those with either nonsignificant quadratic term or c significantly > 0 ("non-negative curvature group," n = 47, 2 with c significantly > 0). We found the negative curvature group had significantly higher maximal VO2/kg (median 37.9 vs. 32.4 ml x min(-1) x kg(-1); P = 0.03) higher resting stroke volume (SV; median 77 vs. 60 ml; P = 0.04), lower resting heart rate (HR; median 72 vs. 82 beats/min, P = 0.04), and higher tissue oxygen extraction at maximal exercise (17.1 +/- 2.2 vs 15.5 +/- 2.1 ml/100 ml; P < 0.01), with tendencies for higher maximal CardOut and SV. We also found the HR vs. VO2 relationship to be negatively curved, with negative curvature in HR associated with the negative curvature in CardOut (P < 0.05), suggesting the curvature in the CardOut vs. VO2 relationship was secondary to curvature in HR vs. VO2. We conclude that the CardOut vs. VO2 relationship is not always linear, and negative curvature in the relationship is associated with higher fitness levels in normal, non-elite-athletic subjects.

Secular trends in incidence of atrial fibrillation in Olmsted County, Minnesota, 1980 to 2000, and implications on the projections for future prevalence

BACKGROUND

Limited data exist on trends in incidence of atrial fibrillation (AF). We assessed the community-based trends in AF incidence for 1980 to 2000 and provided prevalence projections to 2050.

METHODS AND RESULTS

The adult residents of Olmsted County, Minnesota, who had ECG-confirmed first AF in the period 1980 to 2000 (n=4618) were identified. Trends in age-adjusted incidence were determined and used to construct model-based prevalence estimates. The age- and sex-adjusted incidence of AF per 1000 person-years was 3.04 (95% CI, 2.78 to 3.31) in 1980 and 3.68 (95% CI, 3.42 to 3.95) in 2000. According to Poisson regression with adjustment for age and sex, incidence of AF increased significantly (P=0.014), with a relative increase of 12.6% (95% CI, 2.1 to 23.1) over 21 years. The increase in age-adjusted AF incidence did not differ between men and women (P=0.84). According to the US population projections by the US Census Bureau, the number of persons with AF is projected to be 12.1 million by 2050, assuming no further increase in age-adjusted incidence of AF, but 15.9 million if the increase in incidence continues.

CONCLUSIONS

The age-adjusted incidence of AF increased significantly in Olmsted County during 1980 to 2000. Whether or not this rate of increase continues, the projected number of persons with AF for the United States will exceed 10 million by 2050, underscoring the urgent need for primary prevention strategies against AF development.

High density lipoprotein mediated lipid efflux from retinal pigment epithelial cells in culture

BACKGROUND/AIM

[corrected] The transport of radiolabelled photoreceptor outer segments (POS) lipids was investigated by cultured retinal pigment epithelial cells (RPE). Phagocytosis of POS by the RPE is essential to maintain the health and function of the photoreceptors in vivo. POS are phagocytised at the apical cell surface of RPE cells. Phagocytised POS lipids may be either recycled to the photoreceptors for reincorporation into new POS or they may be transported to the basolateral surface for efflux into the circulation.

RESULTS

The authors have demonstrated that high density lipoprotein (HDL) stimulates efflux of radiolabelled lipids, of POS origin, from the basal surface of RPE cells in culture. Effluxed lipids bind preferentially to HDL species of low and high molecular weight. Effluxed radiolabelled phosphotidyl choline was the major phospholipid bound to HDL, with lesser amounts of phosphatidyl ethanolamine, phosphatidyl inosotol. Effluxed radiolabelled triglycerides, cholesterol, and cholesterol esters also bound to HDL. Lipid free apolipoprotein A-I (apoA-I) and apoA-I containing vesicles also stimulate lipid efflux.

CONCLUSION

The findings suggest a role for HDL and apoA-I in regulating lipid and cholesterol transport from RPE cells that may influence the pathological lipid accumulation associated with age related macular degeneration.

The trained observer better predicts daytime ABPM diastolic blood pressure in hypertensive patients than does an automated (Omron) device

OBJECTIVES

Accurate blood pressure measurement is critical to successful clinical trials. Concerns about observer errors have led to the use of automated oscillometric devices without evidence that their performance is similar to that of trained observers. This study compares blood pressures obtained by trained observers and with an oscillometric device (Omron 705CP) to 24-h ambulatory blood pressure monitoring.

METHODS

We performed a post-hoc analysis of 313 untreated hypertensive patients at the end of the washout phase of a Novartis hypertension trial. Patients had three seated trained observer mercury auscultatory blood pressure measurements followed by 24-h ambulatory blood pressure monitoring. The next day, the ambulatory blood pressure monitoring was removed and three seated readings were obtained with an Omron 705CP. Correlations for systolic blood pressure and diastolic blood pressure were obtained between daytime ambulatory blood pressure monitoring (0900 and 2100) and the two office methods. In addition, we investigated the degree of difference of trained observer and Omron measurements from ambulatory blood pressure monitoring.

RESULTS

For systolic blood pressure, the correlation with ambulatory blood pressure monitoring of the trained observer was significantly better than with that of the Omron 705CP (0.641 vs. 0.555, P=0.01). For diastolic blood pressure values, even greater disparity between the two office method correlations with ambulatory blood pressure monitoring was observed (trained observer=0.593 vs. Omron=0.319, P<0.0001). Both trained observer and Omron readings were consistently higher than ambulatory blood pressure monitoring for systolic blood pressure (P<0.0001) and diastolic blood pressure (P<0.0001). Omron measurements, however, deviated from ambulatory blood pressure monitoring more than those of the trained observer (P<0.0001 for systolic blood pressure and diastolic blood pressure).

CONCLUSIONS

For clinical trials using diastolic blood pressure targets, the Omron 705CP cannot replace the auscultatory blood pressure measurements of a trained observer. For systolic blood pressure, the Omron device and the trained observer had similar correlations with ambulatory blood pressure monitoring; however, both methods gave consistently higher systolic blood pressure values. Further study of oscillometric devices should be conducted before universally replacing auscultatory blood pressure determinations by trained observers in clinical trials.

The impact of observer and patient factors on the occurrence of digit preference for zero in blood pressure measurement in a hypertension specialty clinic: evidence for the need of continued observation

BACKGROUND

Many investigators have reported unconscious over-reporting of the terminal digit zero but little literature exists on observer or patient-related factors that may predict the occurrence. This study analyzes the occurrence of zero preference in 52,827 blood pressure (BP) measurements in 8513 patients by 11 hypertension nurse specialists in the Hypertension Division at Mayo Clinic, Rochester, Minnesota.

METHODS

Data from the electronic database of the Hypertension Division from April 1997 to September 2001 were analyzed for the occurrence of zero preference. Nurse-specific zero preference was stratified on four variables: number of BPs performed, years as hypertension nurse specialist, time of day BP performed (fatigue), and nursing degree. Three patient-specific factors were analyzed: age at visit (stratified by decade), type of care (continuing versus short-term), and hypertension status.

RESULTS

We found significantly increased frequency of zero preference for all BPs with mean frequency of 31% v 20% expected (P < .0001). Individual nurse zero preference varied widely, 22.0% to 53.6% for systolic BP and 22.2% to 40.8% for diastolic BP). Continuing care patients had a higher zero preference than did short-term care patients for both systolic BP (34.5% v 30.2%; P < .0001) and diastolic BP (34.7% v 33.3%; P = .006). Zero preference was also more common at higher categories of hypertension (P < .001). Time of day, nursing degree, patient age, the number of BPs performed, years of service did not affect the occurrence of digit preference.

CONCLUSIONS

Digit preference was demonstrated and varied significantly among well-trained hypertension nurse specialists. Further studies in a larger number of observers are required.

Exertional Changes in Circulating Cardiac Natriuretic Peptides in Patients with Suggested Coronary Artery Disease

BACKGROUND

We measured plasma brain natriuretic peptide (BNP) and N-terminal atrial natriuretic peptide (ANP) levels before and after exercise stress testing and correlated results with echocardiographic evidence of ischemia.

METHODS

Sixty patients with left ventricular ejection fraction greater than 50% referred for clinically indicated exercise echocardiogram were studied. Peptides were measured at rest and 5 minutes after symptom-limited exercise.

RESULTS

Echocardiography was positive for ischemia in 19 (32%). With exercise, ANP level increased in all 60 patients (median at rest 2501 [799-6440]-3167 [977-8563] pg/mL after exercise [P < .0001]). BNP increased in 54 patients (90%) (19 [<3.9-213]-30 [<3.9-318] pg/mL [P < .0001]). In multivariable analysis, both exercise BNP level and exertional change in BNP were closely associated with rest BNP (P < .0001); both were also significantly associated with change in wall-motion score index and workload (P = .001 and P = .01, respectively). Exercise ANP was strongly related to rest level (P < .0001); change in ANP was related to workload (P < .0001).

CONCLUSION

In patients with suggested coronary artery disease, exertional levels of BNP are influenced not only by development of stress-induced ischemia, but also by resting levels.

Safety of exercise stress testing in patients with abnormal concentrations of serum potassium

The objective of this study was to determine the safety of performing exercise stress testing in patients with abnormal serum potassium concentrations. Data were reviewed from 9,084 patients (mean age 63 +/- 12 years) referred for exercise echocardiography who had serum potassium measured <48 hours before the test were reviewed, and the occurrence of arrhythmias during stress testing was determined. Of 10,272 studies, 9,067 (88%) were in patients with normokalemia and 1,205 (12%) were in patients with abnormal serum potassium concentrations: 309 (26%) with hypokalemia (mean 3.4 +/- 0.16 mmol/L) and 896 (74%) with hyperkalemia (mean 5.1 +/- 0.19 mmol/L). Ventricular and supraventricular ectopy were common during exercise. Only 1 patient (potassium 4.9 mmol/L) had sustained ventricular tachycardia; all other episodes were nonsustained. Although ventricular and supraventricular ectopy are common during exercise testing, life-threatening arrhythmias are not. Exercise testing is generally safe despite mild to moderate hypokalemia or hyperkalemia.

Outcomes after normal dobutamine stress echocardiography and predictors of adverse events: long-term follow-up of 3014 patients

AIMS

Normal exercise echocardiography predicts a good prognosis. Dobutamine stress echocardiography (DSE) is generally reserved for patients with comorbidities which preclude exercise testing. We evaluated predictors of adverse events after normal DSE.

METHODS AND RESULTS

We studied 3014 patients (1200 males, 68+/-12 years) with normal DSE, defined as the absence of wall motion abnormality at rest or with stress. During median follow-up of 6.3 years, all-cause mortality and cardiac events, defined as myocardial infarction and coronary revascularization, occurred in 920 (31%) and 231 (7.7%) patients, respectively. Survival and cardiac event-free probabilities were 95 and 98% at 1 year, 78 and 93% at 5 years, and 56 and 89% at 10 years, respectively. Age, diabetes mellitus, and failure to achieve 85% age-predicted maximal heart rate were independent predictors of mortality and cardiac events. Patients with all three of these characteristics had a 13% probability of cardiac events within the first year and higher risk throughout follow-up.

CONCLUSION

Prognosis after normal DSE is not necessarily benign, but depends on patient and stress test characteristics. Careful evaluation, using clinical and stress data, is required to identify patients with normal DSE who are at increased risk of adverse outcomes during long-term follow-up.

Effects of quinapril on left atrial structural remodeling and arterial stiffness

Left atrial (LA) enlargement, left ventricular (LV) diastolic dysfunction, and increased arterial stiffness are all associated with adverse cardiovascular outcomes. The rate, magnitude, and concordance of modifiability of these risk markers have not been well characterized. Twenty-one patients (mean age 69 +/- 8 years; 52% women) with isolated diastolic dysfunction and indexed LA volumes > or =32 ml/m(2) were randomly assigned to receive either quinapril at a target dose of 60 mg/day or matching placebo for 12 months. Echocardiographic maximum LA volume and LV diastolic function and arterial stiffness by the augmentation index were measured at baseline and 6 and 12 months. Analysis was based on intention to treat. Baseline characteristics were comparable between the treatment (n = 9) and placebo (n = 12) groups. The mean reduction in LA volume of 4.2 +/- 7.8 ml/m(2) in the quinapril group was significant (p = 0.01) compared with the increase in LA volume in the placebo group (5.5 +/- 8.1 ml/m(2)). This represents a relative improvement of 9.7 ml/m(2). Change in LV filling pressure in terms of E/e' and diastolic function grade did not reach significance. A reduction in the augmentation index was associated with a decrease in indexed LA volume (odds ratio 11, p = 0.046), independent of changes in systolic blood pressure. In conclusion, LA structural remodeling appeared reversible with quinapril, which occurred in parallel with an improvement in arterial stiffness but independent of blood pressure changes.

Comparison of usefulness of echocardiographic Doppler variables to left ventricular end-diastolic pressure in predicting future heart failure events

We sought to determine whether the echocardiographic Doppler parameters of left ventricular diastolic dysfunction predict future heart failure (HF) events and, if so, which parameters best predict HF. We also examined whether the predictive ability of echocardiographic Doppler parameters was related to their prediction of left ventricular end-diastolic pressure (LVEDP). We studied patients who underwent cardiac catheterization and echocardiography performed within a 30-day period. The end point was HF, defined as new-onset or recurrent HF diagnosed by a physician and requiring the initiation or modification of treatment of HF. We identified 289 patients (mean age 63.5 +/- 12.6 years) with a mean follow-up of 10.9 +/- 10.2 months. A total of 24 HF events occurred. LVEDP was a significant predictor of HF univariately and independently in multiple regression models after adjustment for ejection fraction. In Cox models adjusted for age, gender, LVEDP, and ejection fraction, only the left atrial volume index and early mitral inflow to early diastolic tissue velocity (E/e') ratio remained predictive of HF. A multiple regression model, including all echocardiographic variables, showed a persistent, although attenuated, relation of early to late mitral inflow velocity (E/A) ratio and E/e' with LVEDP (p = 0.06 and p = 0.002, respectively). The addition of E/e' or the left atrial volume indexed to body surface area, but not E/A, to the clinical history and left ventricular ejection fraction provided incremental prognostic information. A LVEDP of > or =20 mm Hg, E/e' ratio of > or =15, and left atrial volume index of > or =23 ml/m(2) identified those with a higher risk of HF. In conclusion, invasively determined LVEDP is an independent predictor of future HF events. E/e' and the left atrial volume indexed to body surface area are the best independent predictors of future HF and provide prognostic information incremental to the clinical history and left ventricular ejection fraction.

Correspondence between the adult treatment panel III criteria for metabolic syndrome and insulin resistance

OBJECTIVE

The aim of the present study was to assess the diagnostic accuracy of the Adult Treatment Panel III (ATP-III) definition of the metabolic syndrome in identifying insulin-resistant individuals and to explore alternative approaches to improve identification of insulin-resistant individuals among asymptomatic adults from the general population.

RESEARCH DESIGN AND METHODS

The sample consisted of 256 non-Hispanic white subjects without treated hypertension or diabetes, from the Rochester (Minnesota) Heart Family Study (123 men and 133 women; aged 20-60 years). Frequently sampled intravenous glucose tolerance tests were performed in all subjects. The reference standard for insulin resistance was determined by Bergman's minimal model; insulin resistance was defined as an insulin sensitivity index <2 x 10 min(-1) . microU(-1) . ml(-1). Component metabolic syndrome measures included blood pressure determined by sphygmomanometer; fasting serum triglycerides, HDL cholesterol, and glucose concentrations determined enzymatically; and waist circumference determined by tape measure.

RESULTS

By ATP-III criteria, the prevalence of metabolic syndrome was 15.6% (16.3% in men and 15.1% in women; P = 0.465). The presence of metabolic syndrome had low sensitivity to identify insulin resistance (45% in men and 39% in women; sex difference, P = 0.137) but high specificity (93% in men and 95% in women; sex difference, P = 0.345). Based on the area under the receiver operating characteristic curve (AUC) constructed by counting metabolic syndrome components as recommended by ATP-III, diagnostic accuracy was fair (AUC = 0.797 in men and 0.747 in women). When component metabolic syndrome measures were considered as quantitative traits rather than dichotomized, use of waist circumference alone, rather than counting metabolic syndrome components, improved diagnostic accuracy for insulin resistance (in men, AUC = 0.906, P = 0.001; in women, AUC = 0.822, P = 0.10).

CONCLUSIONS

Application of the ATP-III metabolic syndrome criteria provides good specificity but low sensitivity to screen asymptomatic white adults for insulin resistance. Measuring just waist circumference is simpler and may provide greater accuracy for identifying insulin resistance.

Prediction of Cardiovascular Outcomes With Left Atrial Size

OBJECTIVES

We sought to compare left atrial (LA) volume to LA area and diameter for the prediction of adverse cardiovascular outcomes.

BACKGROUND

The incremental value of LA volume compared with LA area or diameter as a cardiovascular risk marker has not been evaluated prospectively for patients with sinus rhythm or atrial fibrillation (AF).

METHODS

Left atrial size was assessed with biplane LA volume, four-chamber LA area, and M-mode dimension for 423 patients (mean age 71 +/- 8 years, 56% men) who were prospectively followed for development of first AF, congestive heart failure, stroke, transient ischemic attack, myocardial infarction, coronary revascularization, and cardiovascular death.

RESULTS

Of the 317 subjects in sinus rhythm at baseline, 62 had 90 new events during a mean follow-up of 3.5 +/- 2.3 years. All three LA size parameters were independently predictive of combined outcomes (all p < 0.0001). The overall performance for the prediction of cardiovascular events was greatest for LA volume (area under the receiver operator characteristic curve: indexed LA volume 0.71; LA area 0.64; LA diameter 0.59). A graded association between the degree of LA enlargement and risk of cardiovascular events was only evident for indexed LA volume. For subjects with AF, there was no association between LA size and cardiovascular events.

CONCLUSIONS

Left atrial volume is a more robust marker of cardiovascular events than LA area or diameter in subjects with sinus rhythm. The predictive utility of LA size for cardiovascular events in AF was poor, irrespective of the method of LA size quantitation.

Dobutamine stress echocardiography in patients with diabetes mellitus: enhanced prognostic prediction using a simple risk score

OBJECTIVES

We sought to determine the prognostic value of dobutamine stress echocardiography (DSE) for predicting long-term outcomes in a large cohort with diabetes mellitus and to develop a simple risk score using clinical and echocardiographic data.

BACKGROUND

Neither risk scores nor long-term prognostic value of DSE has been described in a large diabetic population.

METHODS

We studied 2,349 patients with diabetes mellitus (1,338 men, 67 +/- 11 years of age) during a follow-up of 5.4 +/- 2.2 years.

RESULTS

Mortality and morbidity (myocardial infarction and late coronary revascularization) occurred in 1,044 (44%) and 309 (13%) patients, respectively. Addition of stress echocardiographic variables to the clinical and rest echocardiographic model provided incremental prognostic information for predicting mortality (chi-square = 243 to 270, p < 0.0001) and morbidity (chi-square = 38 to 78, p < 0.0001). For each end point, a simple risk score was derived according to the estimated values of beta coefficients of multivariate predictors (insulin therapy, smoking, failure to achieve target heart rate, percentage of ischemic segments, and impaired left ventricular systolic function) and resulted in an assessment of risk among all age groups. The C-statistic values were 0.60 to 0.64, indicating modest discrimination. The estimated five-year event-free survivals of patients in three risk categories were 94%, 86%, and 80% for morbidity (p < 0.00001) and 69%, 60%, and 47% for mortality (p < 0.0001).

CONCLUSIONS

In patients with diabetes mellitus, a simple and practical risk score using clinical variables and results of DSE stratified patients into three risk groups for mortality and cardiovascular morbidity.

Association of plasma homocysteine with coronary artery calcification in different categories of coronary heart disease risk

OBJECTIVE

To Investigate the association of plasma homocystelne with coronary artery calcification (CAC) in strata based on 10-year risk of coronary heart disease (CHD) in a cohort enriched in persons with hypertension.

PARTICIPANTS AND METHODS

Fasting plasma homocystelne was measured by liquid chromatography electrospray tandem mass spectrometry. Coronary artery calcification was measured noninvasively by electron beam computed tomography and CAC score calculated using the method of Agatston et al. The 10-year CHD risk was calculated based on the Framingham risk score. The association of homocysteine with log-transformed CAC score was assessed in the pooled sample and within each risk stratum by linear regression after adjustment for conventional risk factors.

RESULTS

In the 1071 participants studied, homocysteine was associated with CAC quantity (P = .01) after adjustment for CHD risk factors (age, male sex, total and high-density lipoproteln cholesterol, diabetes, history of smoking, body mass Index, and systolic blood pressure), serum creatinine, and statin and hypertension medication use. When the association was assessed in strata based on 10-year CHD risk, homocysteine was significantly (P = .003) associated with CAC quantity in participants at Intermediate 10-year risk of CHD (6%-20%) independent of other risk factors but not in those at lower risk or higher risk.

CONCLUSION

Plasma homocysteine is associated with quantity of CAC Independent of CHD risk factors. When studied in categories of 10-year CHD risk, the association was significant in participants at intermediate risk but not in those at low or high risk. Plasma homocysteine levels may have clinical utility as a marker of CHD risk in such individuals.