Temporal trends in event rates after Q-wave myocardial infarction: the Framingham Heart Study

BACKGROUND

Short-term (<30 day) mortality after Q-wave myocardial infarction (MI) has declined over the decades, but it is unclear if rates of long-term sequelae after Q-wave MI have improved.

METHODS AND RESULTS

In 546 Framingham Heart Study subjects (388 men with a mean age of 60 years; 158 women with a mean age of 69 years) with an initial recognized Q-wave MI from 1950 through 1989, we investigated time trends in risk for coronary heart disease (CHD) death (n=199), all-cause mortality (n=287), reinfarction (n=108), and congestive heart failure (CHF; n=121). With 1950 through 1969 as the reference period, hazards ratios (HRs) for these outcomes were determined for the 1970s and 1980s. Trend analyses across the 3 time periods were performed for each outcome. Compared with the 1950 through 1969 reference period, the HRs for CHD death were lower in subsequent decades (1970 through 1979: HR, 0.69; 95% CI, 0.49 to 0.98; 1980 through 1989: HR, 0.48; 95% CI, 0.33 to 0.72). All-cause mortality also declined (1970 through 1979: HR, 0.70; 95% CI, 0.0.52 to 0.94; 1980 through 1989: HR, 0.59; 95% CI, 0.43 to 0.81). There were no significant temporal changes in the risks for recurrent MI or CHF.

CONCLUSIONS

Substantial reductions in risk of CHD death and all-cause mortality occurred over these 4 decades, coincident with improvements in post-MI therapies. The absence of a decline in CHF incidence may be due to improved post-MI survival of individuals with depressed left ventricular systolic function who are at high risk for CHF.

Missense mutations in the insulin promoter factor-1 gene predispose to type 2 diabetes

The transcription factor insulin promoter factor-1 (IPF-1) plays a central role in both the development of the pancreas and the regulation of insulin gene expression in the mature pancreatic beta cell. A dominant-negative frameshift mutation in the IPF-l gene was identified in a single family and shown to cause pancreatic agenesis when homozygous and maturity-onset diabetes of the young (MODY) when heterozygous. We studied the role of IPF-1 in Caucasian diabetic and nondiabetic subjects from the United Kingdom. Three novel IPF-1 missense mutations (C18R, D76N, and R197H) were identified in patients with type 2 diabetes. Functional analyses of these mutations demonstrated decreased binding activity to the human insulin gene promoter and reduced activation of the insulin gene in response to hyperglycemia in the human beta-cell line Nes2y. These mutations are present in 1% of the population and predisposed the subject to type 2 diabetes with a relative risk of 3.0. They were not highly penetrant MODY mutations, as there were nondiabetic mutation carriers 25-53 years of age. We conclude that mutations in the IPF-1 gene may predispose to type 2 diabetes and are a rare cause of MODY and pancreatic agenesis, with the phenotype depending upon the severity of the mutation.

Cross-classification of JNC VI blood pressure stages and risk groups in the Framingham Heart Study

BACKGROUND

The recently published Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) includes a classification of blood pressure stages and a new risk stratification component. Patients with high-normal blood pressure or hypertension are stratified into risk group A (no associated cardiovascular disease risk factors, no target organ damage or cardiovascular disease); group B (> or =1 associated cardiovascular disease risk factor excluding diabetes, no target organ damage or cardiovascular disease); or group C (diabetes or target organ damage or cardiovascular disease).

OBJECTIVE

To examine the prevalence of risk groups and blood pressure stages in a community-based sample.

METHODS

We evaluated 4962 subjects from the Framingham Heart Study and Framingham Offspring Study examined between 1990 and 1995. We cross-classified men and women separately according to their JNC VI blood pressure stages and risk groups.

RESULTS

In the whole sample, 43.7% had optimal or normal blood pressure and 13.4% had high-normal blood pressure; 12.9% had stage 1 hypertension and 30.0% had stage 2 or greater hypertension or were receiving medication. As blood pressure stage increased, the proportion of subjects in group A decreased, whereas the proportion in group C increased. Among those with high-normal blood pressure or hypertension, only 2.4% (all women) were in risk group A, 59.3% were in group B, and 38.2% were in group C. In the high-normal or hypertensive group, 39.4% qualified for lifestyle modification as the initial intervention according to JNC VI recommendations, whereas 60.6% were eligible for initial drug therapy or were already receiving drug therapy. Nearly one third of high-normal subjects were in risk group C, in which early drug therapy may be needed. Among those in stage 1, only 4.0% were in group A, in which prolonged lifestyle modification is recommended.

CONCLUSIONS

These results provide a foundation for estimating the number of individuals with hypertension who fall into different risk groups that require different treatment approaches. With nearly 50 million individuals with hypertension in the United States, there are important implications for clinicians and policymakers if JNC VI recommendations are widely adopted in clinical practice.

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.

Prevalence and correlates of elevated serum creatinine levels: the Framingham Heart Study

BACKGROUND

Elevated serum creatinine (SCr) levels are a predictor of end-stage renal disease, but little is known about the prevalence of elevated SCr levels and their correlates in the community.

METHODS

In this cross-sectional, community-based sample, SCr levels were measured in 6233 adults (mean age, 54 years; 54% women) who composed the "broad sample" of this investigation. A subset, consisting of 3241 individuals who were free of known renal disease, cardiovascular disease, hypertension, and diabetes, constituted the healthy reference sample. In this latter sample, sex-specific 95th percentiles for SCr levels (men, 136 micromol/L [1.5 mg/dL]; women, 120 micromol/L [1.4 mg/dL]) were labeled cutpoints. These cutpoints were applied to the broad sample in a logistic regression model to identify prevalence and correlates of elevated SCr levels.

RESULTS

The prevalence of elevated SCr levels was 8.9% in men and 8.0% in women. Logistic regression in men identified age, treatment for hypertension (odds ratio [OR], 1.75; 95% confidence interval [CI], 1.27-2.42), and body mass index (OR, 1.08; 95% CI, 1.01-1.15) as correlates of elevated SCr levels. Additionally, men with diabetes who were receiving antihypertensive medication were more likely to have raised SCr values (OR, 2.94; 95% CI, 1.60-5.39). In women, age, use of cardiac medications (OR, 1.58; 95% CI, 1.10-2.96), and treatment for hypertension (OR, 1.42; 95% CI, 1.07-1.87) were associated with elevated SCr levels.

CONCLUSIONS

Elevated SCr levels are common in the community and are strongly associated with older age, treatment for hypertension, and diabetes. Longitudinal studies are warranted to determine the clinical outcomes of individuals with elevated levels of SCr and to examine factors related to the progression of renal disease in the community.

Prevalence and clinical outcome of mitral-valve prolapse

BACKGROUND

Mitral-valve prolapse has been described as a common disease with frequent complications. To determine the prevalence of mitral-valve prolapse in the general population, as diagnosed with the use of current two-dimensional echocardiographic criteria, we examined the echocardiograms of 1845 women and 1646 men (mean [+/-SD] age, 54.7+/-10.0 years) who participated in the fifth examination of the offspring cohort of the Framingham Heart Study.

METHODS

Classic mitral-valve prolapse was defined as superior displacement of the mitral leaflets of more than 2 mm during systole and as a maximal leaflet thickness of at least 5 mm during diastasis, and nonclassic prolapse was defined as displacement of more than 2 mm, with a maximal thickness of less than 5 mm.

RESULTS

A total of 84 subjects (2.4 percent) had mitral-valve prolapse: 47 (1.3 percent) had classic prolapse, and 37 (1.1 percent) had nonclassic prolapse. Their age and sex distributions were similar to those of the subjects without prolapse. None of the subjects with prolapse had a history of heart failure, one (1.2 percent) had atrial fibrillation, one (1.2 percent) had cerebrovascular disease, and three (3.6 percent) had syncope, as compared with unadjusted prevalences of these findings in the subjects without prolapse of 0.7, 1.7, 1.5, and 3.0 percent, respectively. The frequencies of chest pain, dyspnea, and electrocardiographic abnormalities were similar among subjects with prolapse and those without prolapse. The subjects with prolapse were leaner (P<0.001) and had a greater degree of mitral regurgitation than those without prolapse, but on average the regurgitation was classified as trace or mild.

CONCLUSIONS

In a community based sample of the population, the prevalence of mitral-valve prolapse was lower than previously reported. The prevalence of adverse sequelae commonly associated with mitral-valve prolapse in studies of patients referred for that diagnosis was also low.

Congestive heart failure in subjects with normal versus reduced left ventricular ejection fraction: prevalence and mortality in a population-based cohort

OBJECTIVES

The purpose of this study was to assess the relative proportions of normal versus impaired left ventricular (LV) systolic function among persons with congestive heart failure (CHF) in the community and to compare their long-term mortality during follow-up.

BACKGROUND

Several hospital-based investigations have reported that a high proportion of subjects with CHF have normal LV systolic function. The prevalence and prognosis of CHF with normal LV systolic function in the community are not known.

METHODS

We evaluated the echocardiograms of 73 Framingham Heart Study subjects with CHF (33 women, 40 men, mean age 73 years) and 146 age- and gender-matched control subjects (nested case-control study). Impaired LV systolic function was defined as an LV ejection fraction (LVEF) <0.50.

RESULTS

Thirty-seven CHF cases (51%) had a normal LVEF; 36 (49%) had a reduced LVEF. Women predominated in the former group (65%), whereas men constituted 75% of the latter group. During a median follow-up of 6.2 years, CHF cases with normal LVEF experienced an annual mortality of 8.7% versus 3.0% for matched control subjects (adjusted hazards ratio = 4.06, 95% confidence interval 1.61 to 10.26). Congestive heart failure cases with reduced LVEF had an annual mortality of 18.9% versus 4.1% for matched control subjects (adjusted hazards ratio = 4.31, 95% confidence interval 1.98 to 9.36).

CONCLUSIONS

Normal LV systolic function is often found in persons with CHF in the community and is more common in women than in men. Although CHF cases with normal LVEF have a lower mortality risk than cases with reduced LVEF, they have a fourfold mortality risk compared with control subjects who are free of CHF.

Heritability of heart rate variability: the Framingham Heart Study

BACKGROUND

There is evolving evidence that heart rate (HR) is genetically determined. Heart rate variability (HRV) measured by power spectral analysis provides quantitative phenotypic markers of autonomic nervous system activity. Reported determinants of HR and HRV only partially explain their variability in the population. The purpose of this study was to assess the heritability of HR and HRV and estimate the contribution of genetic factors to their variance.

METHODS AND RESULTS

Subjects who underwent ambulatory recordings at a routine examination were eligible; subjects with congestive heart failure, coronary artery disease, diabetes mellitus, and those taking cardioactive medications were excluded. We analyzed high-frequency power, low-frequency power, very low-frequency power, total power, low-frequency/high-frequency ratio, and the standard deviation of normal R-R intervals from 2-hour continuous ECG recordings. Heritability analysis was done by studying correlations between siblings (n=682, in 291 sibships, 517 pairs) and between spouse pairs (n=206 pairs) after adjusting for important covariates. Results from separate models were combined to estimate the components of variance attributable to measured covariates, additive genetic effects (heritability), and household effects. After adjusting for covariates, the correlations were consistently higher among siblings (0.21 to 0.26) compared with spouses (0.01 to 0.19). The measured covariates in general accounted for 13% to 40% of the total phenotypic variance, whereas genetic factors accounted for 13% to 23% of the variation among HR and HRV measures.

CONCLUSIONS

Heritable factors may explain a substantial proportion of the variance in HR and HRV. These results highlight the contribution of genetic versus environmental factors to autonomic nervous system activity.

Association of left ventricular dilatation and hypertrophy with chronotropic incompetence in the Framingham Heart Study

BACKGROUND

Chronotropic incompetence and left ventricular (LV) dilatation have both been shown to be markers of an adverse cardiovascular prognosis. Chronotropic incompetence has been described in patients with symptomatic LV dilatation and dysfunction, but the effect of asymptomatic LV dilatation and hypertrophy on exercise heart rate response has not been well characterized.

METHODS AND RESULTS

Members of the Framingham Offspring Study underwent M-mode echocardiography and graded exercise testing as part of a routine evaluation. Subjects receiving beta-blockers and digitalis and subjects with preexisting coronary heart disease, heart failure, and baseline ST-segment abnormalities were excluded. Chronotropic incompetence was assessed in 2 ways: (1) failure to achieve an age--predicted target heart rate and (2) a low chronotropic index, a measure of heart rate response that takes into account effects of age, resting heart rate, and physical fitness. Echocardiographic variables studied included LV diastolic and systolic dimensions, LV wall thickness, LV mass, and fractional shortening. There were 1414 men and 1601 women eligible for analyses; failure to reach target heart rate occurred in 20% of men and 23% of women; a low chronotropic index was noted in 14% of men and 12% of women. In unadjusted categorical analyses, an abnormally high LV mass, as defined by exceeding the 90th percentile predicted value of a healthy reference group, was associated with failure to achieve target heart rate in men (31% vs 18%, odds ratio [OR] 2.05, 95% confidence interval [CI] 1.49 to 2.83) and women (34% vs 20%, OR 2.09, 95% CI 1.63 to 2.69). Similarly, an abnormally high LV mass was predictive of a low chronotropic index in men (18% vs 13%, OR 1. 47, 95% CI 1.01 to 2.14) and women (17% vs 10%, OR 1.78, 95% CI 1.29 to 2.45). When considered as a continuous variable, LV diastolic dimension predicted failure to achieve target heart rate in men (ageadjusted OR for 1 SD increase 1.30, 95% CI 1.00 to 1.33) and in women (age-adjusted OR 1.30, 95% CI 1.12 to 1.50). Similarly, LV diastolic dimension predicted low chronotropic index in men (age-adjusted OR 1.22, 95% CI 1.05 to 1.42) and in women (age-adjusted OR 1.18, 95% CI 1.01 to 1.39). After also adjusting for resting blood pressure, physical activity, and other potential confounders, LV mass, when considered as a continuous variable, remained predictive of failure to achieve target heart rate in men (adjusted OR 1.23, 95% CI 1.06 to 1.42) and a low chronotropic index in men (adjusted OR 1.26, 95% CI 1.06 to 1.49). Among women, LV diastolic dimension predicted failure to achieve target heart rate (adjusted OR 1.27, 95% CI 1.12 to 1.45) and low chronotropic index (adjusted OR 1.18, 95% CI 1.01 to 1.39), whereas in men it predicted low chronotropic index (adjusted OR 1.22, 95% CI 1.04 to 1.42).

CONCLUSIONS

In this asymptomatic, population-based cohort, chronotropic incompetence was predicted by increased LV mass and cavity size; among men, it was also predicted by depressed systolic function.

Blood pressure response during treadmill testing as a risk factor for new-onset hypertension. The Framingham heart study

BACKGROUND

Although systolic blood pressure (SBP) response to exercise has been shown to predict subsequent hypertension in small samples of men, this association has not been studied in a large population-based sample of middle-aged men and women. The purpose of this study was to examine, in normotensive subjects, the relations of SBP and diastolic blood pressure (DBP) during the exercise and recovery periods of a graded treadmill test to the risk of developing new-onset hypertension.

METHODS AND RESULTS

BP data from exercise testing in 1026 men and 1284 women (mean age, 42+/-10 years; range, 20 to 69 years) from the Framingham Offspring Study who were normotensive at baseline were related to the incidence of hypertension 8 years later. New-onset hypertension, defined as an SBP >/=140 mm Hg or DBP >/=90 mm Hg or the initiation of antihypertensive drug treatment, occurred in 228 men (22%) and 207 women (16%). Exaggerated SBP (Ex-SBP 2) and DBP (Ex-DBP 2) response and delayed recovery of SBP (R-SBP 3) and DBP (R-DBP 3) were defined as an age-adjusted BP greater than the 95th percentile during the second stage of exercise and third minute of recovery, respectively. After multivariable adjustment, Ex-DBP 2 was highly predictive of incident hypertension in both men (OR, 4.16; 95% CI, 2.15, 8.05) and women (OR, 2.17; CI, 1.19, 3.96). R-SBP 3 was predictive of hypertension in men in a multivariable model that included exercise duration and peak exercise BP (OR, 1.92; CI, 1.00, 3.69). Baseline resting SBP (chi2, 23.4 in men and 34.7 in women) and DBP (chi2, 11.3 in men and 13.1 in women) had stronger associations with new-onset hypertension than exercise DBP (chi2, 16.4 in men and 6.1 in women) and recovery SBP (chi2, 6.5 in men and 2.1 in women) responses.

CONCLUSIONS

An exaggerated DBP response to exercise was predictive of risk for new-onset hypertension in normotensive men and women. An elevated recovery SBP was predictive of hypertension in men. These findings may reflect subtle pathophysiological features in the preclinical stage of hypertension.

Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Heart Study)

Little information is available on the prevalence and determinants of valvular regurgitation in the general population. This study sought to assess the prevalence and clinical determinants of mitral (MR), tricuspid (TR), and aortic (AR) regurgitation in a population-based cohort. Color Doppler echocardiography was performed in 1,696 men and 1,893 women (aged 54 +/- 10 years) attending a routine examination at the Framingham Study. After excluding technically poor echocardiograms, MR, TR, and AR were qualitatively graded from trace to severe. Multiple logistic regression analysis was used to examine the association of clinical variables with MR and TR (more than or equal to mild severity) and AR (more than or equal to trace severity). MR and TR of more than or equal to mild severity was seen in 19.0% and 14.8% of men and 19.1% and 18.4% of women, respectively, and AR of more than or equal to trace severity in 13.0% of men and 8.5% of women. The clinical determinants of MR were age (odds ratio [OR] 1.3/9.9 years, 95% confidence interval [CI] 1.2 to 1.5), hypertension (OR 1.6; 95% CI 1.2 to 2.0), and body mass index (OR 0.8/4.3 kg/m2; 95% CI 0.7 to 0.9). The determinants of TR were age (OR 1.5/9.9 years; 95% CI 1.3 to 1.7), body mass index (OR 0.7/4.3 kg/m2; 95% CI 0.6 to 0.8), and female gender (OR 1.2; 95% CI 1.0 to 1.6). The determinants of AR were age (OR 2.3/9.9 years; 95% CI 2.0 to 2.7) and male gender (OR 1.6; 95% CI 1.2 to 2.1). A substantial proportion of healthy men and women had detectable valvular regurgitation by color Doppler echocardiography. These data provide population-based estimates for comparison with patients taking anorectic drugs.

The association of chronic cough with the risk of myocardial infarction: the Framingham Heart Study

PURPOSE

A persistent inflammatory response accompanying chronic infections may contribute to the risk of coronary atherothrombosis. Recent studies have reported an association between chronic respiratory infections and an increased risk of coronary heart disease; however, these reports have not accounted for important confounders such as impaired lung function.

METHODS

We considered chronic cough as an indicator of chronic lung infection or inflammation in the original Framingham Heart Study participants aged 47 to 89 years. Chronic cough was defined as a cough present for at least 3 months in the preceding year and was categorized as either nonproductive or productive. The association of chronic cough with myocardial infarction was examined for six consecutive examination cycles (1965 to 1979) among participants free of myocardial infarction at the baseline examination. In a secondary analysis, plasma fibrinogen levels were measured during examination cycle 10 (1965 to 1967) in a subgroup of the study sample (n = 1,288). Multivariable logistic regression analysis was performed adjusting for age, gender, smoking status, forced vital capacity, and other known risk factors.

RESULTS

The cross-sectional pooling method yielded 15,656 person-examinations in 3,637 subjects. During follow-up, there were 291 incident myocardial infarctions. Chronic nonproductive cough (odds ratio [OR] 1.8, 95% confidence interval [CI] 1.1 to 2.8) and chronic productive cough (OR 1.6, CI 1.1 to 2.4) were independent predictors of myocardial infarction. Results were unchanged when we further adjusted for a history of heart failure. Adjusted plasma fibrinogen levels (mean +/- SD) were greater in those with chronic nonproductive cough than among those without cough (3.2 +/- 0.6 g/L versus 2.9 +/- 0.6 g/dL, P = 0.001).

CONCLUSIONS

These findings provide evidence that chronic cough, a clinical manifestation of pulmonary infection or chronic inflammation, is associated with the risk of myocardial infarction. Acute phase reactants such as plasma fibrinogen may be implicated in this association. Prospective serologic studies of infections as predictors of coronary heart disease risk are warranted.

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.

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.

Segregation analysis of pulmonary function among families in the Framingham Study

Familial aggregation of cross-sectional pulmonary function was examined in 5,003 subjects from 1,408 families participating in the Framingham Study. Subjects, who were members of either the Original Cohort (recruited from 1948 to 1952) or the Offspring Cohort (recruited from 1971 to 1974), underwent spirometry at a mean age of 53 yr. The effects of age, height, weight, and smoking status on FEV1 were evaluated through linear-regression analysis, with separate models for men and women in each cohort. The gender- and cohort-specific standardized residual FEV1 from these models was used as the phenotypic variable in familial correlation and segregation analyses to assess inheritance patterns. In models that assumed no major gene determining FEV1, correlation of pulmonary function was greater for mothers and offspring than for fathers and offspring (p[mo] = 0.190, p[fo] = 0.112; p = 0.06), and sibling correlation exceeded parent-offspring correlation (p[sib] = 0.225; p < 0.01). By comparison with a general model, in which transmission probabilities and residual familial correlations are arbitrary, models that imposed a Mendelian gene were rejected (p < 0.001). A model with no parent-offspring transmission of a major factor, but with residual familial correlation, provided as good a fit as the general model, suggesting that environmental and/or polygenic genetic influences determine FEV1.

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.

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.

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.

Pain behaviors in LBW infants accompany some "nonpainful" caregiving procedures

Painful procedures may lead to both long- and short-term complications in low birth weight (LBW) infants. This study investigated neonatal pain responses (grimace, slight cry expression, increased cry expression, and knee/leg flexion) during six painful and three nonpainful procedures. The 30 LBW infants studied were less than 48 hours of age and less than 34 weeks gestation, with a mean birth weight of 1,320 gm. The design was comparative; data analysis included repeated measures of analysis of variance, independent t-tests, and paired t-tests. The four pain responses were found to be present 75 to 100 percent of the time after painful procedures (suctioning, skin puncture, dressing change or removal, discontinuation of intravenous line, and insertion of a nasogastric tube). They were also found to be present 49 to 69 percent of the time after nonpainful procedures (total position change, addition/withdrawal of fluid from umbilical catheter, and IV administration of medication).

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.

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.

Impaired heart rate response to graded exercise. Prognostic implications of chronotropic incompetence in the Framingham Heart Study

BACKGROUND

Previous reports have suggested that an attenuated exercise heart rate response may be associated with coronary heart disease risk and with mortality. These observations may parallel the association between reduced heart rate variability during normal activities and adverse outcome. This investigation was designed to look at the prognostic implications of exercise heart rate response in a population-based sample.

METHODS AND RESULTS

In this prospective cohort investigation, 1575 male participants (mean age, 43 years) in the Framingham Offspring Study who were free of coronary heart disease, who were not taking beta-blockers, and who underwent submaximal treadmill exercise testing (Bruce protocol) were studied. Heart rate response was assessed in three ways: (1) failure to achieve 85% of the age-predicted maximum heart rate, which has been the traditional definition of chronotropic incompetence; (2) the actual increase in heart rate from rest to peak exercise; and (3) the ratio of heart rate to metabolic reserve used by stage 2 of exercise ("chronotropic response index"). Proportional hazards analyses were used to evaluate the associations of heart rate responses with all-cause mortality and with coronary heart disease incidence during 7.7 years of follow-up. Failure to achieve target heart rate occurred in 327 (21%) subjects. During follow-up there were 55 deaths (14 caused by coronary heart disease) and 95 cases of incident coronary heart disease. Failure to achieve target heart rate, a smaller increase in heart rate with exercise, and the chronotropic response index were predictive of total mortality and incident coronary heart disease (P <.01). Failure to achieve target heart rate remained predictive of incident coronary heart disease even after adjusting for age, ST-segment response, physical activity, and traditional coronary disease risk factors (adjusted hazard ratio, 1.75; 95% confidence interval, 1.11 to 2.74; P=.02). After adjusting for the same factors, the increase in exercise heart rate remained inversely predictive of total mortality (P=.04) and coronary heart disease incidence (P=.0003). The chronotropic response index also was predictive of total mortality (P=.05) and incident coronary heart disease (P=.001) after adjusting for age and other risk factors.

CONCLUSIONS

An attenuated heart rate response to exercise, a manifestation of chronotropic incompetence, is predictive of increased mortality and coronary heart disease incidence.

Doppler diastolic filling indexes in relation to disease states

This study compares mean Doppler-derived diastolic filling indexes in a variety of disease states in a large, population-based sample. Pulse-wave Doppler was used to examine 880 eligible participants of the Framingham Heart Study. Peak velocity of early flow and late flow, ratio of early to late peak velocities, atrial filling fraction, and early filling wave acceleration and deceleration times were obtained. Multiple linear regression analyses were performed comparing mean values for individuals with hypertension, diabetes, coronary disease, cardiovascular disease, and pulmonary disease. Hypertension was associated with a greater peak velocity late flow (0.027 m/sec; 95% confidence interval, 0.006, 0.047; p = 0.011), and diabetes was associated with a larger mean deceleration time (0.12 sec, confidence interval, 0.002, 0.021; p = 0.016). In multivariate analyses, hypertension continued to show a strong association with altered Doppler diastolic filling patterns, p value 0.009, whereas in diabetes, the multivariate p value was 0.28.

Unexplained gradual-onset Q wave patterns. A case series from the Framingham Study

Original cohort members of the Framingham Study were studied to determine prognosis associated with unexplained (gradual-onset) Q wave patterns detected on routine electrocardiograms (ECGs). Biennial ECGs were obtained on subjects beginning in 1948. The index ECG was read independently and then serially in relation to all previous tracings for evidence of myocardial infarction. Proportional hazards modeling was used to assess the risk for outcomes in those with unexplained (gradual-onset) Q wave patterns compared with subjects with unrecognized myocardial infarcts (abrupt-onset Q waves) and compared with referent subjects. Unexplained Q wave patterns developed in 53 men and 39 women. Subjects with unexplained Q wave patterns had less than 40% of the risk for myocardial infarction or coronary death as compared with those with unrecognized myocardial infarction after adjusting for risk factors (hazard ratio, 0.38; 95% confidence interval, 0.19, 0.78; P = .008) and a trend toward a lower risk for overall mortality (adjusted hazard ratio, 0.73; 95% confidence interval, 0.46, 1.16; P = .18). Risks for myocardial infarction or coronary death and overall mortality were similar in subjects with unexplained Q wave patterns and referent subjects in the fully adjusted models. Detection of prominent Q waves on an ECG requires comparison with prior tracings to differentiate the unexplained Q wave pattern from the unrecognized infarct, conditions that have significantly different prognostic implications.

Sleep and healing in intensive care settings

Maximizing healing in the ICU environment requires active promotion of sleep as a nursing intervention. Changing practice requires a two-pronged approach: developing an expanded knowledge base related to the physiological effects of sleep and especially healing, and minimizing the impact of the traditional ICU system on sleep deprivation.