Large Community-based Population Research Articles

The Challenge of Achieving National Cholesterol Goals in Patients With Diabetes

This study analyzed lipid results from a large community-based population of patients with diabetes to assess the feasibility of attaining the standard and new optional LDL-based lipid goals using currently available lipid-lowering medications. Ambulatory patients with diabetes who were interviewed as part of the Vermont Diabetes Information System trial with a reported LDL were analyzed. Patients were categorized into high-risk and very-high-risk cardiovascular status. For patients not at the LDL goal, the required changes in therapy to achieve the goal were assessed. Of the entire cohort, 49.4% (321 of 650) had LDL <100 mg/dl. According to the National Cholesterol Education Program, 29.4% (191 of 650) of patients were very high risk and have an optional LDL goal of <70 mg/dl. Only 15.7% (30 of 191) of very-high-risk patients had an LDL <70 mg/dl. Based on our analysis of high-risk patients, 17 of 459 (3.7%) would require more than two lipid-lowering drugs to achieve an LDL <100 mg/dl. In the very-high-risk group, we estimate that 26.2% (50 of 191) of patients will not reach LDL <70 mg/dl with two lipid-lowering medications. In many patients with diabetes and cardiovascular disease, it will be difficult to attain an LDL goal of <70 mg/dl. Approximately 25% of patients will require more than two lipid-lowering drugs at maximal doses to attain this goal, assuming 100% tolerance of lipid-lowering medications.

Hypertrophic cardiomyopathy in a large community-based population: clinical outcome and identification of risk factors for sudden cardiac death and clinical deterioration

ObjectivesThis study evaluates the clinical course and identifies risk factors for sudden cardiac death (SCD) and clinical deterioration in hypertrophic cardiomyopathy (HCM) in a large community-based population. Comparison was made with data from six tertiary referral and six nonreferral institutions. BackgroundHypertrophic cardiomyopathy is a disease with marked heterogeneity in clinical presentation and prognosis. Risk factors for SCD are not well defined in patients free of referral bias. MethodsBetween 1970 and 1999, 225 consecutive patients (mean age [±SD] 41±16 years) were examined and followed at yearly intervals. ResultsForty-four deaths were recorded of which 27 cases were cardiovascular. Fourteen patients died suddenly, six were successfully resuscitated, and seven patients died of congestive heart failure. The annual mortality, annual cardiac mortality, and annual mortality due to sudden death were 1.3%, 0.8%, and 0.6%, respectively. At least one New York Heart Association (NYHA) functional class deterioration was reported in 33% of the patients with a significant (≥50 mm Hg) left ventricular outflow tract (LVOT) gradient in contrast to 7% without obstruction. The presence of syncope was related to SCD (p < 0.05). Younger age and more severe functional limitation distinguishes patients from in hospital-based centers from the ones in community-based centers. ConclusionsHypertrophic cardiomyopathy is a benign disease in an unselected population with a low incidence of cardiac death. Syncope was associated with a higher incidence of SCD and patients with a significant LVOT obstruction were more susceptible to clinical deterioration.

Association of hyperglycemia with reduced heart rate variability (The Framingham Heart Study)

This study was designed to examine the association of heart rate variability (HRV) with blood glucose levels in a large community-based population. Previous reports have shown HRV to be reduced in diabetics, suggesting the presence of abnormalities in neural regulatory mechanisms. There is scant information about HRV across the spectrum of blood glucose levels in a population-based cohort. One thousand nine hundred nineteen men and women from the Framingham Offspring Study, who underwent ambulatory electrocardiographic recordings at a routine examination, were eligible. HRV variables included the SD of normal RR intervals (SDNN), high-frequency (HF, 0.15 to 0.40 Hz) and low-frequency (LF, 0.04 to 0.15 Hz) power, and LF/HF ratio. Fasting plasma glucose levels were used to classify subjects as normal (<110 mg/dl; n = 1,779), as having impaired fasting glucose levels (110 to 125 mg/dl; n = 56), and as having diabetes mellitus (DM ≥126 mg/dl or receiving therapy; n = 84). SDNN, LF and HF power, and LF/HF ratio were inversely related to plasma glucose levels (p <0.0001). SDNN and LF and HF powers were reduced in DM subjects (4.28 ± 0.03, 6.03 ± 0.08, and 4.95 ± 0.09) and in subjects with impaired fasting glucose levels (4.37 ± 0.04, 6.26 ± 0.10, and 5.06 ± 0.11) compared with those with normal fasting glucose (4.51 ± 0.01, 6.77 ± 0.02, and 5.55 ± 0.02, all p <0.005), respectively. After adjusting for covariates (age, sex, heart rate, body mass index, antihypertensive and cardiac medications, systolic and diastolic blood pressures, smoking, and alcohol and coffee consumption), LF power and LF/HF ratio were lower in DM subjects than in those with normal fasting glucose (p <0.005). HRV is inversely associated with plasma glucose levels and is reduced in diabetics as well as in subjects with impaired fasting glucose levels. Additional research is needed to determine if low HRV contributes to the increased cardiovascular morbidity and mortality described in subjects with hyperglycemia.

Impact of reduced heart rate variability on risk for cardiac events. The Framingham Heart Study.

Although heart rate variability (HRV) is altered in a variety of pathological conditions, the association of reduced HRV with risk for new cardiac events has not been studied in a large community-based population. The first 2 hours of ambulatory ECG recordings obtained on subjects of the Framingham Heart Study who were free of clinically apparent coronary heart disease or congestive heart failure were reprocessed to assess HRV. Five frequency-domain measures and three time-domain measures were obtained. The associations between HRV measures and the incidence of new cardiac events (angina pectroris, myocardial infarction, coronary heart disease death, or congestive heart failure) were assessed with proportional hazards regression analyses. There were 2501 eligible subjects with a mean age of 53 years. During a mean follow-up of 3.5 years, cardiac events occurred in 58 subjects. After adjustment for age, sex, cigarette smoking, diabetes, left ventricular hypertrophy, and other relevant risk factors, all HRV measures except the ratio of low-frequency to high-frequency power were significantly associated with risk for a cardiac event (P = .0016 to .0496). A one-standard deviation decrement in the standard deviation of total normal RR intervals (natural log transformed) was associated with a hazard ratio of 1.47 for new cardiac events (95% confidence interval of 1.16 to 1.86). The estimation of HRV by ambulatory monitoring offers prognostic information beyond that provided by the evaluation of traditional cardiovascular disease risk factors.

Is the Use of Psychotropic Drugs Associated with Increased Risk of Ischemic Heart Disease?

Earlier reports of associations between panic disorder, depression, and ischemic heart disease have not evaluated the role of the drugs used to treat these conditions. As part of a larger study on reducing cardiovascular disease in an entire community, we estimated the association between psychotropic drugs and ischemic heart disease in a large community-based population using a cohort study design. We defined exposure as current use of psychotropic medications at the time of the health interview. We determined ischemic heart disease by International Classification of Diseases, 9th revision, Clinical Modification, codes and by an epidemiologic algorithm using clinical diagnostic criteria. An elevated risk for clinically significant ischemic cardiac events was moderately associated with benzodiazepine use [relative risk (RR) = 2.0; 90% confidence interval (CI) = 1.1-3.9] and strongly associated with antidepressant use (RR = 5.7; 90% CI = 2.6-12.8), although the latter estimate was based on only six antidepressant users who had an ischemic event.

Reduced heart rate variability and mortality risk in an elderly cohort. The Framingham Heart Study.

The prognostic implications of alterations in heart rate variability have not been studied in a large community-based population. The first 2 hours of ambulatory ECG recordings obtained on original subjects of the Framingham Heart Study attending the 18th biennial examination were reprocessed to assess heart rate variability. Subjects with transient or persistent nonsinus rhythm, premature beats > 10% of total beats, < 1 hour of recording time, processed time < 50% of recorded time, and those taking antiarrhythmic medications were excluded. The associations between heart rate variability measures and all-cause mortality during 4 years of follow-up were assessed. There were 736 eligible subjects with a mean age (+/- SD) of 72 +/- 6 years. The following five frequency domain measures and three time domain measures were obtained: very-low-frequency power (0.01 to 0.04 Hz), low-frequency power (0.04 to 0.15 Hz), high-frequency power (0.15 to 0.40 Hz), total power (0.01 to 0.40 Hz), the ratio of low-frequency to high-frequency power, the standard deviation of total normal RR intervals, the percentage of differences between adjacent normal RR intervals that are > 50 milliseconds, and the square root of the mean of the squared differences between adjacent normal RR intervals. During follow-up, 74 subjects died. In separate proportional hazards regression analyses that adjusted for relevant risk factors, very-low-frequency power (P < .0001), low-frequency power (P < .0001), high-frequency power (P = .0014), total power (P < .0001), and the standard deviation of total normal RR intervals (P = .0019) were significantly associated with all-cause mortality. When all eight heart rate variability measures were assessed in a stepwise analysis that included other risk factors, low-frequency power entered the model first (P < .0001); thereafter, none of the other measures of heart rate variability significantly contributed to the prediction of all-cause mortality. A 1 SD decrement in low-frequency power (natural log transformed) was associated with 1.70 times greater hazard for all-cause mortality (95% confidence interval of 1.37 to 2.09). The estimation of heart rate variability by ambulatory monitoring offers prognostic information beyond that provided by the evaluation of traditional risk factors.