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Biomedical subjects

R S Vasan

Publications and source records attributed to R S Vasan.

At least 19 recordsLinked to original sources
PubMed2007

Risk factors for acute ischaemic stroke in young adults in South India.

BACKGROUND: Stroke is a leading cause of death and disability in developing countries, afflicting individuals at a young age. The contribution of established vascular risk factors to ischaemic stroke in young adults has not been evaluated systematically in Indians. METHODS: We conducted a case control study in 214 South Indian patients with first acute ischaemic stroke that occurred between the ages of 15 and 45 years, 99 age and sex matched hospital controls and 96 community controls. We compared the prevalence of the following risk factors: smoking, elevated blood pressure, high fasting blood glucose and abnormal lipids. RESULTS: Compared with community controls, stroke patients had a higher prevalence of smoking (multivariable adjusted odds ratio (OR) 7.77, 95% CI 1.93 to 31.27), higher systolic blood pressure (OR per SD increment of 1.88, 95% CI 1.01 to 3.49) and fasting blood glucose (OR per SD increment of 4.55, 95% CI 1.63 to 12.67), but lower high density lipoprotein (HDL) cholesterol (OR per SD increment of 0.17, 95% CI 0.09 to 0.30). Compared with hospital controls, stroke patients had a higher prevalence of smoking (OR 3.95, 95% CI 1.61 to 9.71) and lower HDL cholesterol (OR per SD increment 0.27, 95% CI 0.17 to 0.44). The presence of > or = 3 metabolic syndrome components was associated strongly with stroke (OR 4.76, 95% CI 1.93 to 11.76; OR 2.09, 95% CI 1.06 to 4.13) compared with community and hospital controls. CONCLUSIONS: Key components of the metabolic syndrome and smoking are associated with ischaemic stroke in young South Indian adults. Our observations underscore the importance of targeting adolescents and young adults for screening and prevention to reduce the burden of ischaemic stroke in young adults.

Adolescent↗
PubMed2006

Cross-sectional relations of serum aldosterone and urine sodium excretion to urinary albumin excretion in a community-based sample.

Experimental models suggest that increased aldosterone and sodium intake are associated with renovascular damage and resultant proteinuria. We hypothesized that serum aldosterone and urinary sodium would be associated with urinary albumin excretion, an indicator of kidney damage. We evaluated 2700 participants (53% women, mean age 58 years) from the Framingham Offspring Study who attended a routine examination between 1995 and 1998, who were free of heart failure and renal failure, and underwent testing for serum aldosterone, spot urinary sodium, and urinary albumin excretion (urine albumin/creatinine ratio, UACR), the latter two indexed to urinary creatinine. Stepwise multivariable linear regression was used to evaluate the relations between UACR with urinary sodium index and serum aldosterone. In multivariable regression, log urinary sodium index was associated positively with log-UACR (P<0.0001). UACR levels in the fourth and fifth quintiles of urinary sodium index were 24% (95% confidence interval (CI) 3-49%), and twofold higher (95% CI 72-150%), respectively, relative to the lowest quintile (P-value for trend across quintiles <0.001). In multivariable models, log-transformed aldosterone was not related to log-UACR. The top quintile of serum aldosterone levels was associated with a 21% higher (95% 1-44%) UACR levels relative to the lowest quintile. Urinary albumin excretion was strongly and positively associated in a continuous fashion with urinary sodium excretion, whereas a weaker nonlinear positive relation with serum aldosterone was noted. Our cross-sectional observations raise the possibility that dietary salt intake may be associated with early renovascular damage.

Albuminuria↗
PubMed2001

Assessment of frequency of progression to hypertension in non-hypertensive participants in the Framingham Heart Study: a cohort study.

BACKGROUND: Patients with optimum (<120/80 mm Hg), normal (120-129/80-84 mm Hg), and high normal (130-139/85-89 mm Hg) blood pressure (BP) may progress to hypertension (>140/90 mm Hg) over time. We aimed to establish the best frequency of BP screening by assessing the rates and determinants of progression to hypertension. METHODS: We assessed repeated BP measurements in individuals without hypertension (BP<140/90 mm Hg) from the Framingham Study (4200 men, 5645 women; mean age 52 years) who attended clinic examinations during 1978-94. The incidence of hypertension (or use of antihypertensive treatment) and its determinants were studied. FINDINGS: A stepwise increase in hypertension incidence occurred across the three non-hypertensive BP categories; 5.3% (95% CI 4.4-6.3%) of participants with optimum BP, 17.6% (15.2-20.3%) with normal, and 37.3% (33.3-41.5%) with high normal BP aged below age 65 years progressed to hypertension over 4 years. Corresponding 4-year rates of progression for patients 65 years and older were 16.0% (12.0-20.9), 25.5% (20.4-31.4), and 49.5% (42.6-56.4), respectively. Obesity and weight gain also contributed to progression; a 5% weight gain on follow-up was associated with 20-30% increased odds of hypertension. INTERPRETATION: High normal BP and normal BP frequently progress to hypertension over a period of 4 years, especially in older adults. These findings support recommendations for monitoring individuals with high normal BP once a year, and monitoring those with normal BP every 2 years, and they emphasise the importance of weight control as a measure for primary prevention of hypertension.

Adult↗
PubMed2001

Impact of high-normal blood pressure on the risk of cardiovascular disease.

BACKGROUND: Information is limited regarding the absolute and relative risk of cardiovascular disease in persons with high-normal blood pressure (systolic pressure of 130 to 139 mm Hg, diastolic pressure of 85 to 89 mm Hg, or both). METHODS: We investigated the association between blood-pressure category at base line and the incidence of cardiovascular disease on follow-up among 6859 participants in the Framingham Heart Study who were initially free of hypertension and cardiovascular disease. RESULTS: A stepwise increase in cardiovascular event rates was noted in persons with higher baseline blood-pressure categories. The 10-year cumulative incidence of cardiovascular disease in subjects 35 to 64 years of age who had high-normal blood pressure was 4 percent (95 percent confidence interval, 2 to 5 percent) for women and 8 percent (95 percent confidence interval, 6 to 10 percent) for men; in older subjects (those 65 to 90 years old), the incidence was 18 percent (95 percent confidence interval, 12 to 23 percent) for women and 25 percent (95 percent confidence interval, 17 to 34 percent) for men. As compared with optimal blood pressure, high-normal blood pressure was associated with a risk-factor-adjusted hazard ratio for cardiovascular disease of 2.5 (95 percent confidence interval, 1.6 to 4.1) in women and 1.6 (95 percent confidence interval, 1.1 to 2.2) in men. CONCLUSIONS: High-normal blood pressure is associated with an increased risk of cardiovascular disease. Our findings emphasize the need to determine whether lowering high-normal blood pressure can reduce the risk of cardiovascular disease.

Adult↗
PubMed2001

Elevated midlife blood pressure increases stroke risk in elderly persons: the Framingham Study.

BACKGROUND: Stroke risk predictions are traditionally based on current blood pressure (BP). The potential impact of a subject's past BP experience (antecedent BP) is unknown. We assessed the incremental impact of antecedent BP on the risk of ischemic stroke. METHODS: A total of 5197 stroke-free subjects (2330 men) in the community-based Framingham Study cohort were enrolled from September 29, 1948, to April 25, 1953, and followed up to December 31, 1998. We determined the 10-year risk of completed initial ischemic stroke for 60-, 70-, and 80-year-old subjects as a function of their current BP (at baseline), recent antecedent BP (average of readings at biennial examinations 1-9 years before baseline), and remote antecedent BP (average at biennial examinations 10-19 years earlier), with adjustment for smoking and diabetes mellitus. Models incorporating antecedent BP were also adjusted for baseline BP. The effect of each BP component (systolic BP, diastolic BP, and pulse pressure) was assessed separately. RESULTS: Four hundred ninety-one ischemic strokes (209 in men) were observed in eligible subjects. The antecedent BP influenced the 10-year stroke risk at the age of 60 years (relative risk per SD increment of recent antecedent systolic BP: women, 1.68 [95% confidence interval, 1.25-2.25]; and men, 1.92 [95% confidence interval, 1.39-2.66]) and at the age of 70 years (relative risk per SD increment of recent antecedent systolic BP: women, 1.66 [95% confidence interval, 1.28-2.14]; and men, 1.30 [95% confidence interval, 0.97-1.75]). This effect was evident for recent and remote antecedent BP, consistent in hypertensive and nonhypertensive subjects, and demonstrable for all BP components. CONCLUSIONS: Antecedent BP contributes to the future risk of ischemic stroke. Optimal prevention of late-life stroke will likely require control of midlife BP.

Adult↗
PubMed2000

Interpretation of echocardiographic measurements: a call for standardization.

BACKGROUND: Although echocardiography is used extensively in clinical medicine, guidelines for quantitative interpretation of echocardiographic measurements are unavailable. The goals of this investigation were to provide an overview of scientific standards for formulating reference values, with clinical chemistry used as a model, to evaluate published echocardiographic reference limits, to survey clinical echocardiography laboratories regarding their interpretation of echocardiographic measurements, and to provide recommendations for improving the interpretation and reporting of echocardiographic measurements. METHODS AND RESULTS: We reviewed the original reports of the International Federation of Clinical Chemistry on guidelines for formulating reference values. We obtained published reports on echocardiographic reference limits through searches of electronic databases supplemented by a manual search of relevant bibliographies. We also surveyed echocardiographic laboratories in 35 adult acute-care hospitals in Eastern Massachusetts. Studies on echocardiographic reference values were evaluated with the use of guidelines from clinical chemistry. Responses from the 29 participating echocardiographic laboratories were evaluated for their practice of quantitative echocardiographic interpretation. There is considerable heterogeneity in the echocardiographic reference values available in the literature. There is also a lack of agreement in the literature and among echocardiographers regarding the partitioning of reference values (by sex, ethnicity, or age), the anthropometric measure to be used for indexation, and the choice of cut-points for categorizing values within the abnormal range. CONCLUSIONS: We advocate that echocardiographic reference limits be standardized and a consensus generated regarding the partitioning of reference limits and the indexation of echocardiographic measurements. Such measures can aid in quantitative echocardiographic interpretation and render the results more scientific and consistent.

Adolescent↗
PubMed1999

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.

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

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↗
PubMed1996

The role of hypertension in the pathogenesis of heart failure. A clinical mechanistic overview.

Hypertension plays a key role in the evolution of the syndrome of heart failure. Hypertension has been identified as the chief precursor of left ventricular hypertrophy. Hypertensive left ventricular hypertrophy can lead to ventricular diastolic dysfunction; it is also a risk factor for myocardial infarction, which is a principal cause of left ventricular systolic dysfunction. Asymptomatic left ventricular dysfunction, whether systolic or diastolic, culminates in clinically overt heart failure when a threshold is exceeded or when other precipitating factors are superimposed. The onset of overt heart failure heralds a bleak outcome. These structural and functional changes associated with hypertension evolve over decades and are preventable with effective antihypertensive treatment. These observations emphasize the importance of early diagnosis and effective treatment of hypertension to prevent cardiac complications.

Heart Failure↗
PubMed1996

Echocardiographic evaluation of patients with acute rheumatic fever and rheumatic carditis.

BACKGROUND: Cardiac involvement is the most important component of acute rheumatic fever. The role of echocardiography in the evaluation of rheumatic carditis has not been adequately defined. We used echocardiography in a large sample of patients with acute rheumatic fever to describe morphological abnormalities associated with rheumatic carditis and to assess its role in the diagnosis of rheumatic carditis. METHODS AND RESULTS: Cross-sectional and color Doppler echocardiographic examination was performed in 108 consecutive patients with acute rheumatic fever within 24 to 48 hours of diagnosis. Twenty-eight patients had acute rheumatic fever without clinical evidence of carditis (group 1). Thirty-five patients had a presumed first episode of rheumatic carditis (group 2), and 45 patients had a recurrence of carditis (group 3). Patients in group 1 did not demonstrate any evidence of valvular regurgitation. Mitral regurgitation was the most common Doppler echocardiographic feature in groups 2 (94%) and 3 (84%). Valvular thickening with or without restriction of leaflet mobility was frequently seen in rheumatic carditis. One of every 4 patients with rheumatic carditis demonstrated echocardiographic presence of focal valvular nodules. These nodules were found on the body and the tips of the mitral valve leaflets and disappeared on follow-up. Ventricular dilatation (group 2, 54%; group 3, 74%) and restriction of leaflet mobility (group 3, 37%) were common mechanisms of mitral regurgitation in rheumatic carditis; valve prolapse (group 2, 9%; group 3, 16%) and annular dilatation (group 2, 12%; group 3, 21%) were infrequent. The majority of patients with rheumatic carditis had normal left ventricular systolic function. Congestive heart failure (group 2, 17%; group 3, 40%) was invariably associated with the presence of hemodynamically significant valve lesions. On follow-up, no patient in group 1 developed valvular regurgitation. In group 2 patients, a progressive decrease in left ventricular dimensions was observed without any change in ventricular fractional shortening. Valvular regurgitation remained unchanged in 69% of patients, decreased in 22%, and disappeared in 9%. CONCLUSIONS: In patients with rheumatic carditis, the mitral valve is most often involved and mitral regurgitation is the most common finding on color flow imaging. Mitral regurgitation in rheumatic carditis is related to ventricular dilatation and/or restriction of leaflet mobility. Rheumatic carditis does not result in congestive heart failure in the absence of hemodynamically significant valve lesions. In a quarter of patients with rheumatic carditis, we observed valve nodules that may represent echocardiographic equivalents of rheumatic verrucae. Our study failed to reveal any incremental diagnostic utility of echocardiography and Doppler color flow imaging in rheumatic fever without clinical evidence of carditis.

Acute Disease↗