Biomedical subjects

M G Larson

Publications and source records attributed to M G Larson.

At least 55 records · Page 3Linked to original sources

PubMed1999

Differential impact of systolic and diastolic blood pressure level on JNC-VI staging. Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.

The sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure classifies blood pressure into stages on the basis of both systolic (SBP) and diastolic (DBP) blood pressure levels. When a disparity exists between SBP and DBP stages, patients are classified into the higher stage ("up-staged"). We evaluated the effect of disparate levels of SBP and DBP on blood pressure staging and eligibility for therapy. We examined 4962 Framingham Heart Study subjects between 1990 and 1995 and determined blood pressure stages on the basis of SBP alone, DBP alone, or both. After the exclusion of subjects on antihypertensive therapy (n=1306), 3656 subjects (mean age 58+/-13 years; 55% women) were eligible. In this sample, 64.6% of subjects had congruent stages of SBP and DBP, 31.6% were up-staged on the basis of SBP, and 3.8% on the basis of DBP; thus, SBP alone correctly classified JNC-VI stage in approximately 96% (64.6%+31.6%) of the subjects. Among subjects >60 years of age, SBP alone correctly classified 99% of subjects; in those </=60 years old, SBP alone correctly classified 95%. Of 1488 subjects with high-normal blood pressure or hypertension, who were potentially eligible for drug therapy, 13.0% had congruent elevations of SBP and DBP, 77.7% were up-staged on the basis of SBP, and 9.3% were up-staged on the basis of DBP; SBP alone correctly classified 91%, whereas DBP alone correctly classified only 22%. SBP elevation out of proportion to DBP is common in middle-aged and older persons. SBP appears to play a greater role in the determination of JNC-VI blood pressure stage and eligibility for therapy. Given these results, combined with evidence from hypertension treatment trials, future guidelines might consider a greater role for SBP than for DBP in determining the presence of hypertension, risk of cardiovascular events, eligibility for therapy, and benefits of treatment.

Adult↗

PubMed1998

Accuracy of death certificates for coding coronary heart disease as the cause of death.

BACKGROUND: Death certificates are widely used in epidemiologic and clinical investigations and for national statistics. OBJECTIVE: To examine the accuracy of death certificates for coding coronary heart disease as the underlying cause of death. DESIGN: Community-based inception cohort followed since 1948. SETTING: Framingham, Massachusetts. PATIENTS: 2683 deceased Framingham Heart Study participants. MEASUREMENTS: Sensitivity, specificity, and predictive values of the death certificate. The reference standard was cause of death adjudicated by a panel of three physicians. RESULTS: Among 2683 decedents, the death certificate coded coronary heart disease as the underlying cause of death for 942; the physician panel assigned coronary heart disease for 758. The death certificate had a sensitivity of 83.8% (95% CI, 81.1 % to 86.4%), positive predictive value of 67.4% (CI, 64.4% to 70.4%), specificity of 84.1% (CI, 82.4% to 85.7%), and negative predictive value of 92.9% (CI, 91.7% to 94.1%) for coronary heart disease. The death certificate assigned coronary heart disease in 51.2% of 242 deaths (9.0% of total deaths) for which the physician panel could not determine a cause. Compared with the physician panel, the death certificate attributed 24.3% more deaths to coronary heart disease overall and more than twice as many deaths to coronary heart disease in decedents who were at least 85 years of age. When deaths that were assigned unknown cause by the physician panel were excluded, the death certificate still assigned more deaths to coronary heart disease (7.9% overall and 43.1% in the oldest age group). CONCLUSIONS: Coronary heart disease may be overrepresented as a cause of death on death certificates. National mortality statistics, which are based on death certificate data, may overestimate the frequency of coronary heart disease by 7.9% to 24.3% overall and by as much as two-fold in older persons.

Adult↗

PubMed1998

Calcium antagonists and mortality risk in men and women with hypertension in the Framingham Heart Study.

BACKGROUND: Several recent studies have suggested that calcium antagonist drugs, which are widely used for the treatment of hypertension, are associated with increased risk of cardiovascular disease. These studies have cast doubts on the long-term safety of calcium antagonists. OBJECTIVE: To examine the association of calcium antagonist use with mortality in subjects with hypertension followed up in the Framingham Heart Study. SUBJECTS AND METHODS: We stratified 3539 subjects (mean+/-SD age, 64+/-13 years) from the Framingham Heart Study who had hypertension at routine clinic examinations, according to the use of calcium antagonists and presence of coronary heart disease at the baseline examination. At each follow-up examination (every 2-4 years), subjects were reclassified with regard to the use of calcium antagonists. The end point of the study was all-cause mortality. Hazard ratios and 95% confidence intervals associated with the use of calcium antagonists were obtained using Cox proportional hazards regression models. RESULTS: There were 970 deaths during follow-up. Hazard ratios for mortality associated with the use of calcium antagonists were 0.93 (95% confidence interval, 0.72-1.21; P=.59) for subjects with hypertension without coronary heart disease, and 0.92 (95% confidence interval, 0.69-1.24; P=.58) for those with coronary heart disease at baseline. All models were adjusted for age, sex, current smoking, systolic and diastolic blood pressure, use of beta-blockers, and use of other antihypertensive medications. CONCLUSIONS: In this cohort of 3539 subjects with hypertension there were no differences in mortality among subjects with hypertension using a calcium antagonist compared with those who were not. Results were similar among subjects with hypertension with and without coronary heart disease. The results of ongoing long-term, randomized clinical trials will provide more definitive data on the safety of calcium antagonists.

Adult↗

PubMed1998

Evidence for association and genetic linkage of the angiotensin-converting enzyme locus with hypertension and blood pressure in men but not women in the Framingham Heart Study.

BACKGROUND: There is controversy regarding the association of the angiotensin-converting enzyme deletion-insertion (ACE D/I) polymorphism with systemic hypertension and with blood pressure. We investigated these relations in a large population-based sample of men and women by using association and linkage analyses. METHODS AND RESULTS: The study sample consisted of 3095 participants in the Framingham Heart Study. Blood pressure measurements were obtained at regular examinations. The ACE D/I polymorphism was identified by using a polymerase chain reaction assay. In logistic regression analysis, the adjusted odds ratios for hypertension among men for the DD and DI genotypes were 1.59 (95% confidence interval [CI], 1.13 to 2.23) and 1.18 (95% CI, 0.87 to 1.62), respectively, versus II (chi2 P=.02). In women, adjusted odds ratios for the DD and DI genotypes were 1.00 (95% CI, 0.70 to 1.44) and 0.78 (95% CI, 0.56 to 1.09), respectively (P=.14). In linear regression analysis, there was an association of the ACE DD genotype with increased diastolic blood pressure in men (age-adjusted P=.03, multivariate-adjusted P=.14) but not women. Quantitative trait linkage analyses in 1044 pairs of siblings, by using both ACE D/I and a nearby microsatellite polymorphism of the human growth hormone gene, supported a role of the ACE locus in influencing blood pressure in men but not in women. CONCLUSIONS: In our large, population-based sample, there is evidence for association and genetic linkage of the ACE locus with hypertension and with diastolic blood pressure in men but not women. Our data support the hypothesis that ACE, or a nearby gene, is a sex-specific candidate gene for hypertension. Confirmatory studies in other large population-based samples are warranted.

Adult↗

PubMed1998

Glucose intolerance, physical signs of peripheral artery disease, and risk of cardiovascular events: the Framingham Study.

BACKGROUND: Diabetes and peripheral artery disease (PAD) are acknowledged hallmarks of development of atherosclerotic cardiovascular disease (CVD). The prognostic implications of physical indicators of PAD, compared with and in conjunction with glucose intolerance based on population based data, are not well documented. METHODS AND RESULTS: The influence of carotid and femoral bruits and nonpalpable pedal pulses, with and without glucose intolerance, on development of coronary disease (CHD), congestive heart failure (CHF), and stroke (CVA) was investigated in a cohort of 1672 men and 2264 women ages 47 to 99 years participating in the Framingham Study. Cross-sectional pooling yielded 29,063 2-year person-examination units based on the sample of whom 440 men and 484 women had glucose intolerance develop. Over the 26 years of follow-up, 210 men and 199 women had 1 or more of the specified CVD events. Logistic regression analysis was used to estimate age-adjusted odds ratios comparing incidence of CVD events in subjects with glucose intolerance, signs of PAD, or both conditions with those with neither condition. Glucose intolerance was associated with a 2-fold excess occurrence of physical signs of PAD (P< .01 ). Femoral and carotid bruits were generally associated with greater increased risk of CHD, CHF, and CVA than was glucose intolerance alone. Particularly in women, the concomitant presence of bruits augmented the CVD risk of glucose intolerance. Nonpalpable pedal pulses were a stronger risk factor for CVD end points than glucose intolerance; particularly in men and in both sexes, those with both conditions were at substantially greater risk of CVD events than those with either alone. CONCLUSIONS: Physical findings of PAD appear to signify a compromised arterial circulation to the heart and brain as well as the limbs in persons with glucose intolerance. Persons with the combination are candidates at high risk for CHD, CHF, and CVA.

Aged↗

PubMed1998

Increased left ventricular mass and hypertrophy are associated with increased risk for sudden death.

OBJECTIVES: This study examined the relations of echocardiographically determined left ventricular (LV) mass and hypertrophy to the risk of sudden death. BACKGROUND: Echocardiographic LV hypertrophy is associated with increased risk for all-cause mortality and cardiovascular disease morbidity and mortality. However, little is known about the association of echocardiographic LV hypertrophy with sudden death. METHODS: We examined the relations of LV mass and hypertrophy to the incidence of sudden death in 3,661 subjects enrolled in the Framingham Heart Study who were > or =40 years of age. The baseline examination was performed from 1979 to 1983 and LV hypertrophy was defined as LV mass (adjusted for height) > 143 g/m in men and > 102 g/m in women. During up to 14 years of follow-up there were 60 sudden deaths. Cox models examined the relations of LV mass and LV hypertrophy to sudden death risk after adjusting for known risk factors. RESULTS: The prevalence of LV hypertrophy was 21.5%. The risk factor-adjusted hazard ratio (HR) for sudden death was 1.45 (95% confidence interval [CI] 1.10 to 1.92, p=0.008) for each 50-g/m increment in LV mass. For LV hypertrophy, the risk factor-adjusted HR for sudden death was 2.16 (95% CI 1.22 to 3.81, p=0.008). After excluding the first 4 years of follow-up, both increased LV mass and LV hypertrophy conferred long-term risk of sudden death (HR 1.53, 95% CI 1.01 to 2.28, p=0.047 and HR 3.28, 95% CI 1.58 to 6.83, p=0.002, respectively). CONCLUSIONS: Increased LV mass and hypertrophy are associated with increased risk for sudden death after accounting for known risk factors.

Adult↗

PubMed1998

Reduced heart rate variability and new-onset hypertension: insights into pathogenesis of hypertension: the Framingham Heart Study.

Heart rate variability (HRV) is a useful noninvasive tool to assess cardiac autonomic function. The purpose of this study was to (1) compare measures of HRV between hypertensive and normotensive subjects and (2) examine the role of HRV as a predictor of new-onset hypertension. The first 2 hours of ambulatory ECG recordings obtained from 931 men and 1111 women attending a routine examination at the Framingham Heart Study were processed for HRV. Three time-domain and 5 frequency-domain variables were studied: standard deviation of normal RR intervals (SDNN), percentage of differences between adjacent normal RR intervals exceeding 50 milliseconds, square root of the mean of squared differences between adjacent normal RR intervals, total power (0.01 to 0.40 Hz), high frequency power (HF, 0.15 to 0.40 Hz), low frequency power (LF, 0.04 to 0.15 Hz), very low frequency power (0.01 to 0.04 Hz), and LF/HF ratio. On cross-sectional analysis, HRV was significantly lower in hypertensive men and women. Among 633 men and 801 women who were normotensive at baseline (systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg and not receiving antihypertensive treatment), 119 men and 125 women were newly hypertensive at follow-up 4 years later. After adjustment for factors associated with hypertension, multiple logistic regression analysis revealed that LF was associated with incident hypertension in men (odds ratio per SD decrement [OR], 1.38; 95% confidence interval [CI], 1.04 to 1.83) but not in women (OR, 1.12; 95% CI, 0.86 to 1.46). SDNN, HF, and LF/HF were not associated with hypertension in either sex. HRV is reduced in men and women with systemic hypertension. Among normotensive men, lower HRV was associated with greater risk for developing hypertension. These findings are consistent with the hypothesis that autonomic dysregulation is present in the early stage of hypertension.

Adult↗

PubMed1997

Distribution and categorization of echocardiographic measurements in relation to reference limits: the Framingham Heart Study: formulation of a height- and sex-specific classification and its prospective validation.

BACKGROUND: Despite widespread categorization of echocardiographic measurements, there are no standardized guidelines for partitioning values exceeding reference limits. METHODS AND RESULTS: We used regression analyses to develop sex- and height-specific reference limits for cardiac M-mode measurements (left ventricular [LV] mass, LV wall thickness, and LV and left atrial dimensions) in a healthy reference sample (n=1099) from the Framingham Heart Study. We then examined the distribution of measurements in a broad sample (n=4957) and classified the measurements according to increasing deviation from the height- and sex-specific reference limits and the 95th, 98th, and 99th percentile values for the broad sample (categories 0 through 4, respectively). To validate the categorization scheme, we used multivariable proportional-hazards regression to assess the relations of LV mass and LV wall thickness categories to risk of cardiovascular events and the relations of left atrial size to risk of atrial fibrillation. During a mean follow-up period of 7.7 years, 587 subjects developed new cardiovascular disease events, and 166 subjects developed new-onset atrial fibrillation. After adjustment for known risk factors, there was a 1.2- and 1.3-fold risk of cardiovascular disease events per category of LV wall thickness and LV mass, respectively, and a 1.6-fold risk of atrial fibrillation per category of left atrial size. CONCLUSIONS: Using a large community-based study sample, we propose a classification scheme that provides a standardized and validated framework for partitioning echocardiographic measurements. If adopted, the categorization scheme should promote uniformity in describing measurements among echocardiographic laboratories and enhance the comprehensibility of measurements to clinicians.

Adolescent↗

PubMed1997

Predicting survival in heart failure case and control subjects by use of fully automated methods for deriving nonlinear and conventional indices of heart rate dynamics.

BACKGROUND: Despite much recent interest in quantification of heart rate variability (HRV), the prognostic value of conventional measures of HRV and of newer indices based on nonlinear dynamics is not universally accepted. METHODS AND RESULTS: We have designed algorithms for analyzing ambulatory ECG recordings and measuring HRV without human intervention, using robust methods for obtaining time-domain measures (mean and SD of heart rate), frequency-domain measures (power in the bands of 0.001 to 0.01 Hz [VLF], 0.01 to 0.15 Hz [LF], and 0.15 to 0.5 Hz [HF] and total spectral power [TP] over all three of these bands), and measures based on nonlinear dynamics (approximate entropy [ApEn], a measure of complexity, and detrended fluctuation analysis [DFA], a measure of long-term correlations). The study population consisted of chronic congestive heart failure (CHF) case patients and sex- and age-matched control subjects in the Framingham Heart Study. After exclusion of technically inadequate studies and those with atrial fibrillation, we used these algorithms to study HRV in 2-hour ambulatory ECG recordings of 69 participants (mean age, 71.7+/-8.1 years). By use of separate Cox proportional-hazards models, the conventional measures SD (P<.01), LF (P<.01), VLF (P<.05), and TP (P<.01) and the nonlinear measure DFA (P<.05) were predictors of survival over a mean follow-up period of 1.9 years; other measures, including ApEn (P>.3), were not. In multivariable models, DFA was of borderline predictive significance (P=.06) after adjustment for the diagnosis of CHF and SD. CONCLUSIONS: These results demonstrate that HRV analysis of ambulatory ECG recordings based on fully automated methods can have prognostic value in a population-based study and that nonlinear HRV indices may contribute prognostic value to complement traditional HRV measures.

Aged↗

PubMed1997

Association of cigarette smoking with chronotropic incompetence and prognosis in the Framingham Heart Study.

BACKGROUND: In this study, we sought to determine whether cigarette smoking is associated with chronotropic incompetence and to explore prognostic implications of this association. METHODS AND RESULTS: Members of the Framingham Offspring Study (1468 men and 1642 women) underwent graded exercise. Chronotropic incompetence was assessed in two ways: (1) failure to achieve an age-predicted target heart rate and (2) a low chronotropic index, a heart rate response measure that accounts for effects of age, resting heart rate, and physical fitness. Smokers were more likely to fail to reach target heart rate than were nonsmokers (men, 25% versus 15%, odds ratio [OR], 1.97; 95% confidence interval [CI], 1.51 to 2.56; women, 32% versus 18%; OR, 2.10; 95% CI, 1.63 to 2.61) and were more likely to have a low chronotropic index (men, 17% versus 12%; OR, 1.50; 95% CI, 1.12 to 2.03; women, 17% versus 8%; OR, 2.28; 95% CI, 1.68 to 3.09). These associations persisted after adjustment for age, cardiovascular risk factors, pulmonary function, and ST-segment response to graded exercise. During 8 years of follow-up, there were 48 deaths and 90 incident coronary heart disease events among the men. After adjustment for the same confounders, men who were smokers and failed to achieve target heart rate were at particularly high risk for death (adjusted relative risk [RR], 2.45; 95% CI, 1.14 to 5.24) and for coronary heart disease (adjusted RR, 4.92; 95% CI, 2.84 to 8.53). There were too few end points in women for analysis. CONCLUSIONS: In this population-based cohort, cigarette smoking was predictive of chronotropic incompetence. Male smokers who manifested chronotropic incompetence were at particularly high risk for death and coronary heart disease events.

Adult↗

PubMed1997

A controlled trial of an educational program to prevent low back injuries.

BACKGROUND: Low back injuries are common and costly, accounting for 15 to 25 percent of injuries covered by workers' compensation and 30 to 40 percent of the payments made under that program. The high costs of injury, the lack of effective treatment. and the evidence that there are behavioral risk factors have led to widespread use of employee education programs that teach safe lifting and handling. The effectiveness of those programs, however, has received little rigorous evaluation. METHODS: We evaluated an educational program designed to prevent low back injury in a randomized, controlled trial involving about 4000 postal workers. The program, similar to that in wide use in so-called back schools, was taught by experienced physical therapists. Work units of workers and supervisors were trained in a two-session back school (three hours of training), followed by three to four reinforcement sessions over the succeeding few years. Injured subjects (from both the intervention and the control groups) were randomized a second time to receive either training or no training after their return to work. RESULTS: Physical therapists trained 2534 postal workers and 134 supervisors. Over 5.5 years of follow-up, 360 workers reported low back injuries, for a rate of 21.2 injuries per 1000 worker-years of risk. The median time off from work per injury was 14 days (range, 0 to 1717); the median cost was $204 (range, zero to $190,380). After their return to work, 75 workers were injured again. Our comparison of the intervention and control groups found that the education program did not reduce the rate of low back injury, the median cost per injury, the time off from work per injury, the rate of related musculoskeletal injuries, or the rate of repeated injury after return to work; only the subjects' knowledge of safe behavior was increased by the training. CONCLUSIONS: A large-scale, randomized, controlled trial of an educational program to prevent work-associated low back injury found no long-term benefits associated with training.

Adolescent↗

PubMed1997

Hemodynamic patterns of age-related changes in blood pressure. The Framingham Heart Study.

BACKGROUND: We attempted to characterize age-related changes in blood pressure in both normotensive and untreated hypertensive subjects in a population-based cohort from the original Framingham Heart Study and to infer underlying hemodynamic mechanisms. METHODS AND RESULTS: A total of 2036 participants were divided into four groups according to their systolic blood pressure (SBP) at biennial examination 10, 11, or 12. After excluding subjects receiving antihypertensive drug therapy, up to 30 years of data on normotensive and untreated hypertensive subjects from biennial examinations 2 through 16 were used. Regressions of blood pressure versus age within individual subjects produced slope and curvature estimates that were compared with the use of ANOVA among the four SBP groups. There was a linear rise in SBP from age 30 through 84 years and concurrent increases in diastolic blood pressure (DBP) and mean arterial pressure (MAP); after age 50 to 60 years, DBP declined, pulse pressure (PP) rose steeply, and MAP reached an asymptote. Neither the fall in DBP nor the rise in PP was influenced significantly by removal of subsequent deaths and subjects with nonfatal myocardial infarction or heart failure. Age-related linear increases in SBP, PP, and MAP, as well as the early rise and late fall in DBP, were greatest for subjects with the highest baseline SBP; this represents a divergent rather than parallel tracking pattern. CONCLUSIONS: The late fall in DBP after age 60 years, associated with a continual rise in SBP, cannot be explained by "burned out" diastolic hypertension or by "selective survivorship" but is consistent with increased large artery stiffness. Higher SBP, left untreated, may accelerate large artery stiffness and thus perpetuate a vicious cycle.

Adult↗

PubMed1997

Left ventricular dilatation and the risk of congestive heart failure in people without myocardial infarction.

BACKGROUND: Left ventricular dilatation is a well-recognized precursor of ventricular dysfunction and congestive heart failure after myocardial infarction. The effect of left ventricular dilatation on the risk of heart failure in people initially free of myocardial infarction is not known. METHODS: We examined the relation of the left ventricular end-diastolic and end-systolic internal dimensions, as measured by M-mode echocardiography, to the risk of congestive heart failure in 4744 subjects (2083 men and 2661 women) who had not sustained a myocardial infarction and who were free of congestive heart failure. We used sex-stratified proportional-hazards regression to assess the association between base-line left ventricular internal dimensions and the subsequent risk of congestive heart failure, after adjusting for age, blood pressure, hypertension treatment, body-mass index, diabetes, valve disease, and interim myocardial infarction. RESULTS: Over an 11-year follow-up period, congestive heart failure developed in 74 subjects (38 men and 36 women). The risk-factor-adjusted hazard ratio for congestive heart failure was 1.47 (95 percent confidence interval, 1.25 to 1.73) for an increment of 1 SD in the left ventricular end-diastolic dimension, indexed for height. We obtained similar results using the left ventricular end-systolic dimension (hazard ratio, 1.43; 95 percent confidence interval, 1.24 to 1.65). CONCLUSIONS: An increase in left ventricular internal dimension is a risk factor for congestive heart failure in men and women who have not had a myocardial infarction. Knowledge of the left ventricular dimension improves predictions of the risk of congestive heart failure made on the basis of traditional risk factors, perhaps by aiding in the identification of subjects with subclinical left ventricular dysfunction.

Female↗

PubMed1997

Antecedent hypertension confers increased risk for adverse outcomes after initial myocardial infarction.

Several studies have examined the association of blood pressure (BP) after myocardial infarction (MI) with a risk for adverse outcome; however, few studies have investigated prognosis after MI as a function of BP before MI. Our goal was to examine the relation of antecedent hypertension to risk of adverse outcomes after initial MI. From 1967 to 1990, 404 subjects followed at the Framingham Heart Study developed an initial MI. These subjects were classified on the basis of preinfarction BP into normotensive (BP<140/90 mm Hg and not receiving antihypertensive treatment; n=118), stage I-untreated hypertension (BP 140 to 159/90 to 99 mm Hg; n=89), and stage II to IV or treated hypertension (BP > or =160/100 mm Hg or treated hypertension; n=197). Cox models were used to adjust for age, sex, smoking, glucose intolerance, total cholesterol, and prior cardiovascular disease. Antecedent hypertension was related to risk of adverse outcome after MI. Compared with normotensive individuals, stage II to IV hypertensives were at increased risk for reinfarction (hazard ratio [HR], 2.20; 95% confidence interval [CI], 1.20 to 4.04). A similar but nonsignificant association was seen in stage I hypertensives (HR, 1.91; 95% CI, 0.97 to 3.77). Stage II to IV hypertensives were at increased risk for all-cause mortality compared with normotensive persons (HR, 1.45; 95% CI, 1.07 to 1.98). Thus, even after MI, a history of antecedent hypertension remains predictive of adverse outcome. These findings are consistent with beneficial effects of BP control in primary and secondary prevention settings. Effective BP control may both reduce the risk for an initial MI and improve outcome in the event that an MI occurs.

Aged↗

PubMed1997

Heritability of left ventricular mass: the Framingham Heart Study.

Left ventricular hypertrophy is associated with an increased risk for cardiovascular disease. The known determinants of left ventricular hypertrophy only partially explain its variability. The purpose of this study was to estimate heritability of left ventricular mass. The study sample included adults in the original Framingham Heart Study and the Framingham Offspring Study who were not receiving antihypertensive medications and who were free of coronary heart disease, congestive heart failure, diabetes mellitus, renal insufficiency, valvular heart disease, and severe left ventricular hypertrophy. Intraclass correlations for left ventricular mass among first-degree relatives, second-degree relatives, and unrelated spouse pairs were calculated to determine the contribution of heredity to the variability in left ventricular mass. After adjustments for age, height, weight, and systolic blood pressure, the intraclass correlations between first-degree relatives were .15 (parent-child, P<.001) to .16 (siblings, P<.001), between second-degree relatives the correlation was .06 (P=NS), and between spouses it was .05 (P=NS). The estimated heritability of adjusted left ventricular mass was between .24 and .32. The proportion of the variance in sex-specific left ventricular mass explained by age, height, weight, and systolic blood pressure was .26 in men and .34 in women. On the basis of intraclass correlations for left ventricular mass, incorporation of adjusted left ventricular mass of a parent or sibling would increase the explained variance by an additional .02 to .03. Heredity explains a small, but discernible proportion of the variance in left ventricular mass. Studies are currently under way to identify genetic markers that predict an individual's predisposition to left ventricular hypertrophy. This knowledge may lead to advances in the prevention of left ventricular hypertrophy, which is strongly associated with cardiovascular morbidity and mortality.

Adult↗

PubMed1997

The occurrence of Raynaud's phenomenon in a general population: the Framingham Study.

The prevalence and predisposing conditions for primary and secondary Raynaud's phenomenon (RP) were examined in The Framingham Study based on 16 years of follow-up of a cohort of 4182 men and women. The association with atypical chest pain and migraine headache was also investigated. Over the 16 years of follow-up there were 130 men and 171 women who developed primary RP. The prevalence in women (9.6%) was somewhat higher than in men (8.1%) and 81.4% of the RP was primary. Secondary RP was equally prevalent in men (18.6%) and women (19.7%). The most common causes of secondary RP were beta-blocker use (34.2%), carpal tunnel syndrome (10.5%) and rheumatoid arthritis (7.2%). Primary RP cases differed from noncases by having lower systolic blood pressure (p < or = 0.001) and diastolic blood pressure (p < 0.0001), and more coronary disease (p = 0.009), smoking (p < or = 0.01) and higher blood sugars (p < or = 0.009). Atypical chest pain was present more often than noted previously in The Framingham Study general population survey, and was equally prevalent in primary and secondary RP and in the two sexes. Associated migraine was more prevalent in women (14.4%) than men (5.0%). Vibrating tool use with associated RP occurred in 14.6%.

Adrenergic beta-Antagonists↗

PubMed1996

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

BACKGROUND: 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. METHODS AND RESULTS: 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). CONCLUSIONS: The estimation of HRV by ambulatory monitoring offers prognostic information beyond that provided by the evaluation of traditional cardiovascular disease risk factors.

Adult↗

PubMed1996

Determinants of heart rate variability.

OBJECTIVES: This study sought to examine clinical determinants of heart rate variability and to report normative reference values for eight heart rate variability measures. BACKGROUND: Although the clinical implications of heart rate variability have been described, clinical determinants and normative values of heart rate variability measures have not been studied systematically in a large community-based population. METHODS: The first 2 h of ambulatory electrocardiographic recordings obtained in Framingham Heart Study subjects attending a routine examination were reprocessed for heart rate variability. Recordings with transient or persistent nonsinus rhythm, premature beats > 10% of total beats, < 1-h recording time or processed time < 50% of recorded time were excluded; subjects receiving antiarrhythmic medications also were excluded. Among five frequency domain and three time domain measures that were obtained, low frequency power (0.04 to 0.15 Hz), high frequency power (0.15 to 0.40 Hz) and the standard deviation of total normal RR intervals based on 2-h recordings were selected for the principal analyses. Variables with potential physiologic effects or possible technical influences on heart rate variability measures were chosen for multiple linear regression analysis. Normative values, derived from a subset of healthy subjects, were adjusted for age and heart rate. RESULTS: There were 2,722 eligible subjects with a mean age (+/-SD) of 55 +/- 14 years. Three separate multiple linear regression analyses revealed that higher heart rate, older age, beta-adrenergic blocking agent use, history of myocardial infarction or congestive heart failure, diuretic use, diastolic blood pressure > or = 90 mm Hg, diabetes mellitus, consumption of three or more cups of coffee per day and smoking were associated with lower values of one or more heart rate variability measures, whereas longer processed time, start time in the morning, frequent supraventricular and ventricular premature beats, female gender and systolic blood pressure > or = 160 mm Hg were associated with higher values. Age and heart rate were the major determinants of all three selected heart rate variability measures (partial R2 values 0.125 to 0.389). Normative reference values for all eight heart rate variability measures are presented. CONCLUSIONS: Age and heart rate must be taken into account when assessing heart rate variability.

Adult↗