Effects of brain natriuretic peptide on exercise hemodynamics and neurohormones in isolated diastolic heart failure

BACKGROUND

Experimental models suggest that brain natriuretic peptide (BNP) can modify left ventricular diastolic performance. The aim of this study was to evaluate the effects of BNP on resting and exercise hemodynamics and neurohormones in patients with isolated diastolic heart failure.

METHODS AND RESULTS

Six patients with isolated diastolic heart failure were studied. After baseline hemodynamic measurements were obtained with use of thermistor-tipped pulmonary artery catheters, patients were randomized to receive infusion of BNP or placebo in a single-blind, crossover study. Hemodynamic and neurohormonal parameters were measured at rest after 30 minutes of infusion and during incremental supine bicycle exercise. BNP did not significantly affect resting hemodynamics but attenuated the rise in both pulmonary capillary wedge pressure (placebo, 23 +/- 2 mm Hg; BNP, 16 +/- 2 mm Hg; P < .01) and mean pulmonary artery pressure (placebo, 34 +/- 3 mm Hg; BNP, 29 +/- 3 mm Hg; P < .05) during exercise without affecting changes in heart rate, systemic blood pressure, or stroke volume. In response to BNP, there was significant suppression of plasma aldosterone concentration (placebo, 551 +/- 107 pmol/L; BNP, 381 +/- 56 pmol/L; P < .05).

CONCLUSIONS

BNP infusion causes beneficial hemodynamic and neurohormonal effects during exercise in patients with isolated diastolic heart failure.

Prevalence and aetiology of hypothyroidism in the young

AIMS

To define the prevalence of hypothyroid disease in children and young people, and describe its aetiology.

METHODS

We identified all patients on the Medicines Monitoring Unit (MEMO) database in the Tayside region of Scotland who had received two or more prescriptions for thyroxine during the study period (January 1993 to December 1995). Using this as a surrogate marker of hypothyroidism, we calculated the prevalence of hypothyroidism in those aged less than 22 years. Main outcome measures were prevalence of thyroxine prescription, estimated prevalence of hypothyroidism, and aetiology of the hypothyroidism (determined from case records, and biochemistry and immunology databases).

RESULTS

Of 103,500 residents aged less than 22 years, 140 were identified as receiving thyroxine on prescription, giving a population prevalence of 0.135%. The ratio of male to female was 1:2.8. Acquired hypothyroidism was the commonest aetiology found in 73%, 66% of which had an autoimmune basis. The prevalence of congenital hypothyroidism was 0.027%. Seven had received treatment for malignancy (two primary thyroid). Fifteen per cent of patients had no record of secondary care follow up in Tayside.

CONCLUSIONS

The overall prevalence of hypothyroidism in young people less than 22 years of age is 0.135%, and in the group aged 11-18 years it is 0.113%; these values are at least twice those of previous estimates. This suggests an increase in autoimmune thyroid disease, similar to the rising prevalence of type 1 diabetes, possibly indicating a rising incidence of autoimmunity in young people.

ACE inhibitor use is associated with hospitalization for severe hypoglycemia in patients with diabetes. DARTS/MEMO Collaboration. Diabetes Audit and Research in Tayside, Scotland. Medicines Monitoring Unit

OBJECTIVE

To evaluate the association between the use of ACE inhibitors and hospital admission for severe hypoglycemia and to explore the effects of potential confounding variables on this relationship.

RESEARCH DESIGN AND METHODS

The association between the use of ACE inhibitors and the incidence of hypoglycemia is controversial. A recent study reported that 14% of all hospital admissions for hypoglycemia might be attributable to ACE inhibitors. We performed a nested case-control study, using a cohort of 6,649 diabetic patients taking insulin or oral antidiabetic drugs, on the Diabetes Audit and Research in Tayside, Scotland (DARTS) database. From 1 January 1993 to 30 April 1994, we identified 64 patients who had been admitted to Tayside hospitals with hypoglycemia and selected 440 control patients from the same cohort.

RESULTS

Hypoglycemia was associated with the use of ACE inhibitors (odds ratio [OR] 3.2, 95% CI 1.2-8.3, P = 0.023), whereas use of beta-blockers and calcium antagonists was not associated with an increased risk of hospitalization for hypoglycemia with ORs of 0.9 (95% CI 0.3-3.3) and 1.7 (95% CI 0.2-2.1), respectively. There were significant differences between case and control patients in type of diabetes treatment, diabetes duration, place of routine diabetes care, and congestive cardiac failure. These differences did not confound the relationship between ACE inhibitors and hypoglycemia (adjusted OR 4.3, 95% CI 1.2-16.0).

CONCLUSIONS

The results show that the association between ACE inhibitor therapy and hospital admission for severe hypoglycemia is not explained by these confounding factors. Although ACE inhibitors have distinct advantages over other antihypertensive drugs in diabetes, the risk of hypoglycemia should be considered.

Glaucoma incidence in an unselected cohort of diabetic patients: is diabetes mellitus a risk factor for glaucoma? DARTS/MEMO collaboration. Diabetes Audit and Research in Tayside Study. Medicines Monitoring Unit

AIMS

To evaluate whether diabetes mellitus is a risk factor for the development of primary open angle glaucoma or ocular hypertension (OHT).

METHODS

A historical cohort study of an unselected population comprising all residents of the Tayside region of Scotland was performed using record linkage techniques followed by case note review. Ascertainment of prevalent diabetes was achieved using the Diabetes Audit and Research in Tayside Study (DARTS) validated regional diabetes register. Glaucoma and treated OHT were defined by encashment of community prescriptions and the statutory surgical procedure coding database.

RESULTS

The study population comprised 6631 diabetic subjects and 166 144 non-diabetic subjects aged >40 years without glaucoma or OHT at study entry. 65 patients with diabetes and 958 without diabetes were identified as new cases of glaucoma or treated OHT during the 24 month study period, yielding a standardised morbidity ratio of 127 (95% CI, 96-158). Case note review demonstrated non-differential misclassification of prevalent glaucoma and OHT as incident disease (diabetic cohort 20%, non-diabetic cohort 24%; p=0.56) primarily as a result of non-compliance in medically treated disease. Removing misclassified cases and adjusting for age yielded an incidence of primary open angle glaucoma in diabetes of 1.1/1000 patient years (95% CI, 0.89-1. 31) compared to 0.7/1000 patient years (95% CI, 0.54-0.86) in the non-diabetic cohort; RR 1.57 (95% CI, 0.99-2.48).

CONCLUSIONS

This study failed to confirm an association between diabetes mellitus and primary open angle glaucoma and ocular hypertension. A non-significant increase in diagnosed and treated disease in the diabetic population was observed, but evidence was also found that detection bias contributes to this association.

Physical activity level is an independent predictor of the diurnal variation in blood pressure

OBJECTIVE

The aim of this study was to define the relationship between physical activity and the magnitude of the percentage fall in blood pressure at night (nocturnal dip).

METHODS

We simultaneously monitored 24-h ambulatory blood pressure and measured physical activity by actigraphy in 434 patients. Blood pressure was measured every 20 min; the actigraph integrated an activity score every 10 s. Mean daytime and night-time activity were calculated from mean scores for the 15 min preceding each blood pressure measurement. Nocturnal dip in systolic and diastolic blood pressure (SBP and DBP) were regressed on mean (log-transformed) daytime activity. Mean night-time activity, age, gender, smoking status, body mass index (BMI) and clinic blood pressure were added into a multiple linear regression.

RESULTS

The patient group was heterogeneous in age, gender and mean 24-h blood pressure. Mean daytime activity level was significantly and positively associated with the magnitude of the nocturnal dip in both SBP and DBP. Increased night-time activity was significantly associated with a smaller nocturnal dip. Older patients had a smaller nocturnal dip per log unit daytime activity. Nocturnal dip in SBP was greater in males, and smaller in those taking antihypertensive medications. Smoking, BMI and clinical blood pressure level were not associated with the extent of the nocturnal dip after adjustment for other factors.

CONCLUSIONS

Daytime and night-time physical activity levels are independently and significantly predictive of the magnitude of the nocturnal dip in blood pressure. Variation in activity may confound interpretation of 24-h ambulatory blood pressure monitoring, and contribute to the poor reproducibility of dipper status.

Presence of bacteriuria caused by trimethoprim resistant bacteria in patients prescribed antibiotics: multilevel model with practice and individual patient data

OBJECTIVE

To look for evidence of a relation between antibiotic resistance and prescribing by general practitioners by analysis of prescribing at both practice and individual patient level.

DESIGN

Repeated cross-sectional study in 1995 and 1996.

SETTING

28 general practices in the Ninewells Hospital laboratory catchment area, Tayside, Scotland. SUBJECTS REVIEWED: 8833 patients registered with the 28 practices who submitted urine samples for analysis.

MAIN OUTCOME MEASURES

Resistance to trimethoprim in bacteria isolated from urine samples at practice and individual level simultaneously in a multilevel model.

RESULTS

Practices showed considerable variation in both the prevalence of trimethoprim resistance (26-50% of bacteria isolated) and trimethoprim prescribing (67-357 prescriptions per 100 practice patients). Although variation in prescribing showed no association with resistance at the practice level after adjustment for other factors (P = 0.101), in the multilevel model resistance to trimethoprim was significantly associated with age, sex, and individual-level exposure to trimethoprim (P < 0.001) or to other antibiotics (P = 0.002). The association with trimethoprim resistance was strongest for people recently exposed to trimethoprim, and there was no association for people with trimethoprim exposure more than six months before the date of the urine sample.

DISCUSSION

Analysis of practice level data obscured important associations between antibiotic prescribing and resistance. The results support efforts to reduce unnecessary prescribing of antibiotics in the community and show the added value of individual patient data for research on the outcomes of prescribing.

Reduced growth velocity across the third trimester is associated with placental insufficiency in fetuses born at a normal birthweight: a prospective cohort study

BACKGROUND

While being small-for-gestational-age due to placental insufficiency is a major risk factor for stillbirth, 50% of stillbirths occur in appropriate-for-gestational-age (AGA, > 10th centile) fetuses. AGA fetuses are plausibly also at risk of stillbirth if placental insufficiency is present. Such fetuses may be expected to demonstrate declining growth trajectory across pregnancy, although they do not fall below the 10th centile before birth. We investigated whether reduced growth velocity in AGA fetuses is associated with antenatal, intrapartum and neonatal indicators of placental insufficiency.

METHODS

We performed a prospective cohort study of 308 nulliparous women who subsequently gave birth to AGA infants. Ultrasound was utilised at 28 and 36 weeks' gestation to determine estimated fetal weight (EFW) and abdominal circumference (AC). We correlated relative EFW and AC growth velocities with three clinical indicators of placental insufficiency, namely (1) fetal cerebroplacental ratio (CPR; CPR < 5th centile reflects placental resistance, and blood flow redistribution to the brain - a fetal response to hypoxia); (2) neonatal acidosis after the hypoxic challenge of labour (umbilical artery (UA) pH < 7.15 at birth); and (3) low neonatal body fat percentage (BF%, measured by air displacement plethysmography) reflecting reduced nutritional reserve in utero.

RESULTS

For each one centile reduction in EFW growth velocity between 28 and 36 weeks' gestation, there was a 2.4% increase in the odds of cerebral redistribution (CPR < 5th centile, odds ratio (OR) (95% confidence interval) = 1.024 (1.005-1.042), P = 0.012) and neonatal acidosis (UA pH < 7.15, OR = 1.024 (1.003-1.046), P = 0.023), and a 3.3% increase in the odds of low BF% (OR = 1.033 (1.001-1.067), P = 0.047). A decline in EFW of > 30 centiles between 28 and 36 weeks (compared to greater relative growth) was associated with cerebral redistribution (CPR < 5th centile relative risk (RR) = 2.80 (1.25-6.25), P = 0.026), and a decline of > 35 centiles was associated with neonatal acidosis (UA pH < 7.15 RR = 3.51 (1.40-8.77), P = 0.030). Similar associations were identified between low AC growth velocity and clinical indicators of placental insufficiency.

CONCLUSIONS

Reduced growth velocity between 28 and 36 weeks' gestation among fetuses born AGA is associated with antenatal, intrapartum and neonatal indicators of placental insufficiency. These fetuses potentially represent an important unrecognised cohort at increased risk of stillbirth and may warrant more intensive antenatal surveillance.

Prior trimethoprim use and trimethoprim-resistant urinary tract infection: a nested case-control study with multivariate analysis for other risk factors

Trimethoprim resistance is increasingly prevalent in community-acquired urinary infections. The objective of this study was to evaluate the association between exposure to community-prescribed trimethoprim and other risk factors in subjects and subsequent trimethoprim-resistant urinary tract infection. The design was a nested case-control study using a record-linkage database. Study subjects submitted a urine sample to the Ninewells Hospital Laboratory between July 1993 and December 1995. Antibiotic exposure in subjects with trimethoprim-resistant isolates (cases) was compared with antibiotic exposure in subjects with trimethoprim-susceptible isolates (controls). Study subjects were drawn from the catchment area of a large teaching hospital in Tayside, Scotland. There were 13765 males and females aged 1-106 years who submitted their first urine sample for culture during the study period. After adjustment for significant risk factors and confounding variables, logistic regression analysis showed exposure to trimethoprim [odds ratio (OR) 4.35] or any antibiotic other than trimethoprim (OR 1.32) to be predictive of resistance. The growth of Proteus spp. (OR 115.14) and bacterial growth other than Escherichia coli and Proteus spp. (OR 2.83) were also predictor variables. Hospitalization in the previous 6 months was not independently associated with trimethoprim resistance. In conclusion, trimethoprim resistance was independently associated with exposure to trimethoprim and to antibiotics other than trimethoprim. Reduction in trimethoprim prescribing alone may not reduce the prevalence of trimethoprim resistance.

Brain natriuretic peptide: effect on left ventricular filling patterns in healthy subjects

1. Elevated plasma concentrations of brain natriuretic peptide are found in conditions associated with impaired left ventricular diastolic function. The purpose of this study was to determine whether this peptide actually plays a physiological role in improving myocardial performance in diastole. 2. Nine normal subjects received infusions of brain natriuretic peptide or placebo in a randomized, double-blind, crossover study. Brain natriuretic peptide infusion produced a significant reduction in isovolumic relaxation time (means and 95% confidence interval for difference -10.8 ms, -14.5 to -7.0 ms) (P < 0.01) and significantly increased both the peak E/A velocity (0.54, 0.14-0.94) (P < 0.05) and the E/A time velocity integral (1.09, 0.20-1.98) (P < 0.05). 3. These responses were evident at concentrations of brain natriuretic peptide that produced no associated effects on blood pressure, heart rate or stroke distance. 4. Brain natriuretic peptide infusion in normal subjects significantly reduces isovolumic relaxation time and improves transmitral Doppler flow profiles, suggesting that this peptide may be important in the control of left ventricular diastolic relaxation in man.

The association between coeliac disease and cardiovascular disease

BACKGROUND

Coeliac disease is more prevalent than was previously thought. The association between coeliac disease and cardiovascular outcome is not clear.

AIM

To investigate whether coeliac disease patients have an increased risk of cardiovascular events.

METHODS

A community-based cohort study using a record-linkage database. Three hundred and sixty-seven coeliac patients identified by a positive antiendomysial antibody test or a diagnosis with small bowel biopsy, and 5537 subjects who were tested and had a negative coeliac immunology, were included in the study.

RESULTS

The crude rates of cardiovascular events were 9.5 per 1000 person-years (95% CI: 4.4-14.6) in the coeliac cohort and 8.9 per 1000 person-years (95% CI: 7.6-10.3) in the antiendomysial antibody-negative cohort. Compared with the antiendomysial antibody-negative cohort, the adjusted relative risk of cardiovascular events for coeliac cohort was 1.9 (95% CI: 1.00-3.60). When we excluded patients who had previous hospitalization for cardiovascular disease, the adjusted relative risk was 2.5 (95% CI: 1.22-5.01). The use of any cardiovascular drugs prior to and after entry to the study were 36% and 29% for the coeliac cohort (P = 0.05), and 34% and 26% for the antiendomysial antibody-negative cohort (P < 0.01).

CONCLUSION

Our findings suggest that coeliac disease seems to be associated with an increased risk of cardiovascular outcome.

Is aldosterone the missing link in refractory hypertension?: aldosterone-to-renin ratio as a marker of inappropriate aldosterone activity

Use of the random aldosterone-to-renin ratio (ARR) as a reliable marker of inappropriate aldosterone activity has led to primary aldosteronism (PA) being increasingly diagnosed in hypertensive patients. At least 10% of hypertensives have been found to have PA, the majority of whom presumably have bilateral adrenal hyperplasia or idiopathic hyperaldosteronism as an aetiology for PA. Whilst these patients clearly have excess aldosterone activity, they have in common many features that are found in hypertensive patients in general, amongst which include heightened angiotensin II adrenal sensitivity. Whether these individuals belong within the spectrum of 'essential hypertension' is being debated, but is probably irrelevant clinically since they appear to respond favourably to spironolactone treatment. In addition, there is recent evidence suggesting that these patients overexpress a key enzyme involved in aldosterone production, the aldosterone synthase, the activity of which appears to relate to its genotypic variation.

The influence of physical activity on the variability of ambulatory blood pressure

The aim of this study was to assess the contribution of physical activity levels to blood pressure (BP) variability, and to assess the effect age, gender, body mass index, and use of antihypertensive medications on this relationship. We simultaneously monitored 24-h ambulatory BP by automated recorder and activity by actigraphy in 431 patients. Mean activity scores for the 5, 10, 15, and 20 min preceding each BP measurement were calculated, and BP and heart rate were related to these variables using linear mixed model regression. Various patient characteristics were added to the mixed model as covariates. Patients were heterogeneous in age (48 +/- 13 years), sex (49% men), and average 24-h BP (132/81 +/- 15/10 mm Hg). Mean daytime activity level was 44 +/- 15 U. During the daytime, systolic BP (r = 0.33), diastolic BP (r = 0.29), and heart rate (r = 0.42) correlated best with the average activity for the 15 min preceding each measurement (P < .001). Variance was very high, with activity explaining from 0% to 62% of BP variability for different individuals. Men and the obese had a greater reactivity of systolic BP to activity; older patients and those on antihypertensive therapy had a lower reactivity of heart rate. Blood pressure level is significantly associated with physical activity, but the percentage of variance of BP explained by physical activity varies greatly between individuals. Correlation is strongest between BP and average activity integrated over the previous 15 min. Much of the variance in blood pressure remains unexplained.

Prognosis following first acute myocardial infarction in Type 2 diabetes: a comparative population study

AIMS

To estimate the incidence of death and macrovascular complications after a first myocardial infarction for patients with Type 2 diabetes.

RESEARCH DESIGN

In a retrospective, incidence cohort study in the Tayside Region of Scotland we studied all patients hospitalized with a diagnosis of first acute myocardial infarction from 1 April 1993 to 31 December 1994. The primary endpoint was time to death. Secondary endpoints were 2-year incidence of hospital admission for angina, myocardial infarction, stroke, heart failure, coronary angiography, coronary artery bypass graft (CABG) and percutaneous transluminal coronary angioplasty (PTCA).

RESULTS

The 147 patients with Type 2 diabetes had significantly worse survival with an increase in relative hazard of 67% compared with non-diabetic patients. After adjustment for age, sex, smoking status, prior heart failure, prior angina, delay to hospitalization, site of infarction, drug therapy with aspirin, beta-blockers, streptokinase and hyperlipidaemia and treated hypertension, Type 2 diabetes was still associated with a 40% higher death rate compared with people without diabetes (P < 0.05) There was no significant difference in death rates in those aged over 70 years, but an indication of a trend in younger individuals with a four-fold increase in death rate in those with diabetes aged < 60 years, compared with a rate ratio of 2.6 in those with diabetes aged 61-70 years.

CONCLUSIONS

Among hospitalized patients with first acute myocardial infarction, Type 2 diabetes mellitus is consistently associated with increased mortality and increased hospital admission for heart failure. The estimated 4-year survival rate is only 50%. Our results indicate that younger subjects with Type 2 diabetes and acute myocardial infarction are a high-risk group deserving of special study, and support the argument for aggressive targeting of coronary risk factors among patients with Type 2 diabetes.

Association between allopurinol and mortality in heart failure patients: a long-term follow-up study

AIMS

The aim of the study was to explore the long-term effect of allopurinol on mortality and cardiovascular hospitalisations in heart failure (HF) patients.

METHODS

This is a population-based cohort study using a record-linkage database in Tayside, Scotland. A total of 4785 HF patients (4260 non-users, 267 incident users and 258 prevalent users) were studied between 1993 and 2002.

RESULTS

Compared with non-users, low-dose users in the incident group had a significant increased risk of all-cause mortality, cardiovascular mortality and cardiovascular recurrence (adjusted HR, 1.60, 95%CI 1.26-2.03; 1.70, 1.29-2.23 and 1.44, 1.01-2.07). For the prevalent users, the adjusted HR were 1.27, 0.98-1.64; 1.43, 1.07-1.90 and 1.27, 0.91-1.76 respectively. There was no increased risk of outcome for high-dose users when compared with non-users (adjusted HR, 1.18, 0.84-1.66; 1.14, 0.76-1.71 and 1.36, 0.88-2.10 for the incident users, and 0.86, 0.64-1.15; 0.90, 0.64-1.26; and 1.27, 0.93-1.74 for the prevalent users respectively). High-dose allopurinol was associated with reduced risk of all-course mortality for prevalent users when compared with low-dose (adjusted HR 0.65, 95%CI 0.42-0.99).

CONCLUSIONS

The prevalent high-dose allopurinol use had a lower risk of mortality than the prevalent low-dose use suggesting that allopurinol may be of benefit in HF patients.

Diastolic heart failure

Diastolic heart disease is common and appears to be the primary abnormality in a substantial proportion of all patients with CHF. The epidemiology and natural history of the condition appears different to that of systolic heart failure, resulting in significant morbidity although contributing little to overall mortality. Clinical assessment alone is inadequate to distinguish systolic from diastolic failure, and echocardiography is an essential investigation in the management of these patients. From a therapeutic standpoint an alternative approach to treatment is likely to be indicated, and the results of recent major trials in systolic heart failure cannot necessarily be extrapolated to this group of patients.

Factors associated with trimethoprim-resistant bacteria isolated from urine samples

Urine samples with trimethoprim-resistant or trimethoprim-sensitive Gram-negative bacteria and samples with no bacterial growth (NG) were identified. Age-sex matched community controls were generated with each trimethoprim-resistant case. These four groups were evaluated for exposure. Prior trimethoprim use was significantly more common in the trimethoprim-resistant group when compared with the trimethoprim-sensitive or the NG group. Prior hospitalization was significantly less common in the trimethoprim-resistant than the trimethoprim-sensitive group, but not with the NG group. Prior oestrogen exposure was associated with trimethoprim resistance. There were no associations found for diabetes or prior corticosteroid exposure. Community controls were found to be inappropriate controls for the study of trimethoprim-resistant bacteria in urine samples.

Design issues for drug epidemiology

Despite the difficulties involved in designing drug epidemiology studies, these studies are invaluable for investigating the unexpected adverse effects of drugs. The aim of this paper is to discuss various aspects of study design, particularly those issues that are not easily found in either textbooks or review papers. We have also compared and contrasted drug epidemiology with the randomized controlled trial (RCT) wherever possible. Drug epidemiology is especially useful in the many situations where the RCT is not suitable, or even possible. The study base has to be defined before the appropriate cohort of subjects is assembled. If all of the cases are identified, then a referent sample of controls may be assembled by random sampling of the study base. If all of the cases cannot be assembled, a hypothetical secondary base may need to be created. Preferably, only new-users of the drug should be included, and the risk-ratio will be different for acute users and chronic users. Studies will usually only be possible when researching the unintended effects of drugs. It is difficult to study efficacy because of confounding by indication. In occasional circumstances it may be possible to study efficacy (examples are given). Discussion of the dangers of designing with generalisability in mind is provided. Additionally, the similarities in study design between drug epidemiology and the RCT are discussed in detail, as well as the design-characteristics that cannot be shared between the two methods.

Impact on mortality following first acute myocardial infarction of distance between home and hospital: cohort study

Objective:

To investigate the effect of distance between home and acute hospital on mortality outcome of patients experiencing an incident myocardial infarction (MI).

Design:

Cohort study using a record linkage database.

Setting:

Tayside, Scotland, UK.

Patients:

10 541 patients with incident acute MI between 1994 and 2003 were identified from Tayside hospital discharge data and from death certification data.

Main outcome measures:

MI mortality in the community, all-cause mortality in hospital and all-cause mortality during follow-up.

Results:

4133 subjects died following incident MI in the community (that is, were not hospitalised), 6408 patients survived to be hospitalised and 1010 of these (15.8%) died in hospital. Of 5398 discharged from hospital, 1907 (35.3%) died during a median of 3.2 years of follow-up. After adjustment for rurality and other known risk factors, distance between home and admitting hospital was significantly associated with increased mortality both before hospital admission (adjusted odds ratio (OR), 2.05, 95% CI 1.00 to 4.21 for >9 miles and 1.46, 1.09 to 1.95 for 3–9 miles when compared to <3 miles) and after hospitalisation (adjusted hazard ratio (HR) 1.90, 1.19 to 3.02 and 1.27, 0.96 to 1.68). However, there was no effect of distance on in-hospital mortality (adjusted OR 0.95, 0.45 to 2.03 and 1.02, 0.66 to 1.58).

Conclusion:

The distance between home and hospital of admission may predict mortality in subjects experiencing a first acute MI. This association was found both before and after hospitalisation. Further studies are needed to explore the reasons for this association. However these data provide support for policies that locate services for acute MI closer to where patients live.

Adverse cardiac effects of salt with fludrocortisone in hypertension

The effect of salt on blood pressure (BP) is controversial. A more important question is whether salt can produce cardiac target-organ damage, irrespective of its effect on BP. We assessed the effect of salt with fludrocortisone on QT dispersion and echocardiographic left ventricular diastolic function in a prospective interventional study involving 29 hypertensive subjects with a raised aldosterone/renin ratio who were hospitalized for investigation of possible primary aldosteronism. Each subject over 4 days was given a total of 28.8 g (480 mmol) of sodium chloride and 1.5 mg of fludrocortisone with potassium supplementation. Baseline and posttreatment 12-lead ECGs and echocardiograms were obtained. There were no significant changes in body weight, pulse rate, or BP after treatment with salt and fludrocortisone. Plasma sodium was significantly increased from 141.4 (SD 2.1) to 142.6 (SD 2.4) mmol/L (P:=0.001). QT and QTc dispersion both significantly increased: +19.6 (SD 16.5) ms (95% CI, 13.4 to 25.9) (P:<0.001) and +19.8 (SD 20.9) ms (95% CI, 11.8 to 27.7) (P:<0.001), respectively. There were no significant changes in (n=15) left ventricular dimensions or systolic function, but all diastolic filling indexes, including the preload-independent index, flow propagation velocity (55.49 [SD 10.91] to 48.96 [SD 11.40] cm/s, P:=0.018) worsened, suggesting significant deterioration of left ventricular diastolic function with salt and fludrocortisone. In conclusion, a combination of salt with fludrocortisone increased QT dispersion and impaired left ventricular diastolic relaxation in hypertensive patients with high aldosterone/renin ratios. This raises the possibility that salt may have BP-independent adverse cardiac effects in susceptible hypertensive subjects.