A D Struthers

How often are angiotensin II and aldosterone concentrations raised during chronic ACE inhibitor treatment in cardiac failure

OBJECTIVE Angiotensin II (AII) and aldosterone are not always fully suppressed during chronic angiotensin converting enzyme (ACE) inhibitor treatment. In congestive heart failure (CHF) such failure of hormonal suppression is associated with increased mortality. This study examined how common AII and aldosterone increases are observed during routine clinical practice. PATIENTS AND METHODS 91 patients with symptomatic (mean New York Heart Association class 2.7) CHF (mean (SD) left ventricular ejection fraction 29.9 (8)%, range 9–46%) were studied 4–6 hours after ACE inhibitor dosing. A representative range of ACE inhibitors (enalapril, lisinopril, captopril, perindopril, and fosinopril) was examined. RESULTS Supine measurements showed a wide range of AII (10.5 (25.5) pg/ml), aldosterone (130.8 (136) pg/ml), and serum ACE (12.1 (13.3) EU/l; excludes captopril data) concentrations on diuretics. AII concentrations > 10 pg/ml were seen in 15% of patients, and aldosterone concentrations > 144 pg/ml were seen in 38% of patients. AII concentrations were significantly correlated (p < 0.001) with ACE but not with aldosterone concentrations. Aldosterone concentrations were not significantly correlated with ACE concentrations. CONCLUSIONS AII “reactivation” occurred in 15% and failure of aldosterone suppression in 38% of routine CHF patients taking ACE inhibitor treatment. AII “reactivation” was associated with both low and high levels of ACE activity, which suggests that multiple different mechanisms are at play. In patients with high plasma ACE concentrations, non-compliance should be considered along with inadequate dose titration. In patients with low plasma ACE and high AII concentrations, non-ACE mediated production of AII may be operative. Raised aldosterone concentrations appear to be more common than AII “reactivation”. It is important to establish the cause of detectable or increased AII concentrations in a heart failure patient treated with an ACE inhibitor. The measurement of serum ACE may help to identify the likely cause as poor compliance or inadequate dose.

Oxidative stress in renal dysfunction: mechanisms, clinical sequelae and therapeutic options

Oxidative stress has been increasingly linked to the high incidence of cardiovascular events in patients with chronic kidney disease (CKD), especially as traditional cardiovascular risk factors seem to not be able to account for the huge cardiovascular morbidity and mortality in this population group. Oxidative stress is increased in patients with renal impairment as a result of increased oxidant activity and reduced antioxidant capacity, and this is increased in a graded manner with increasing renal dysfunction. Inflammation, which is also present in CKD, further amplifies the oxidant generation process. The two clinical sequelae of oxidative stress are endothelial dysfunction and left ventricular hypertrophy, which have adverse cardiovascular consequences. With our new understanding of oxidative stress, it is now important to assess treatment options that reduce it in the hope that they reverse endothelial dysfunction and left ventricular hypertrophy and the clinical sequelae of these abnormalities.

The effect of vitamin D replacement on markers of vascular health in stroke patients – A randomised controlled trial

BACKGROUND AND AIMS Low vitamin D levels are associated with increased incidence of future cardiovascular events and are common in stroke patients. We tested whether vitamin D supplementation could reduce blood pressure and improve markers of vascular health in patients who had previously suffered a stroke. METHODS AND RESULTS Randomised, placebo-controlled, double-blind trial. Community-dwelling patients with a history of stroke and baseline 25-hydroxyvitamin D levels <75 nmol/L received 100,000 units of oral vitamin D2 or placebo at baseline. Office and 24 h blood pressure, endothelial function measured by flow-mediated dilatation of the brachial artery, cholesterol, oxidised low density lipoprotein, B-type natriuretic peptide and heart rate turbulence were measured at baseline, 8 weeks and 16 weeks. 58 patients were randomised. Mean age was 67 years, mean baseline blood pressure 128/72 mmHg, mean baseline 25-hydroxyvitamin D level was 38 nmol/L. Serum 25-hydroxyvitamin D levels were higher in the intervention group at 8 weeks compared to placebo (54 vs 42 nmol/L, P = 0.002) and remained higher at 16 weeks. Office systolic and diastolic blood pressure showed no significant change between groups at 8 weeks (systolic 126.1 vs 131.3 mmHg; adjusted P = 0.97); (diastolic 73.1 vs 74.9 mmHg, adjusted P = 0.15). Flow mediated dilatation was significantly higher in the intervention group at 8 weeks (6.9% vs 3.7%, adjusted P = 0.007) but was not significantly different at 16 weeks. CONCLUSIONS High dose oral vitamin D supplementation did not improve blood pressure but produced short-term improvement in endothelial function in stroke patients with well-controlled baseline blood pressure. CLINICAL TRIALS REGISTRATION ISRCTN28737567.

Social deprivation increases cardiac hospitalisations in chronic heart failure independent of disease severity and diuretic non-adherence.

OBJECTIVE To examine whether social deprivation has any independent effect on emergency cardiac hospitalisations in patients with chronic heart failure (CHF). DESIGN Cohort study of 478 patients with CHF who had been hospitalised before 1993 and who were followed up during 1993 and 1994. SETTING Emergency admissions within Tayside acute hospitals. PATIENTS 478 CHF patients who had a previous myocardial infarction, a previous CHF admission, and were on diuretic treatment. MAIN OUTCOME MEASURES Emergency hospital admissions are divided into those for all causes and those for cardiac causes only. RESULTS Social deprivation was significantly associated with an increase in the number of cardiac hospitalisations (p = 0.007). This effect was mainly caused by increasing the proportion of patients hospitalised in each deprivation category (26% in deprivation category 1–2 versus 40% in deprivation category 5–6, p = 0.03). This effect of deprivation was independent of disease severity, as judged by the dose of prescribed diuretic, the death rate, and the duration of each hospital stay. Non-adherence with diuretic treatment could not account for these findings either. CONCLUSIONS Social deprivation increases the chance of a CHF patient being rehospitalised independently of disease severity. Possible explanations are that doctors who look after socially deprived patients have a lower threshold for cardiac hospitalisation of their patients, or that social deprivation alters the way a CHF patient accesses medical care during decompensation. Understanding how social deprivation influences both doctor and patient behaviour in the prehospital phase is now crucial in order to reduce the amplifying effect that social deprivation appears to have on cardiac hospitalisations.

QT interval abnormalities are often present at diagnosis in diabetes and are better predictors of cardiac death than ankle brachial pressure index and autonomic function tests

Objectives: To study serial measures of maximum QT interval corrected for heart rate (QTc) and QT dispersion (QTD) and their association with cardiac mortality patients with non-insulin dependent diabetes and to compare QT abnormalities with other mortality predictors (ankle brachial pressure index (ABPI) and autonomic function tests) in their ability to predict cardiac death. Setting: Teaching hospital. Methods and patients: QT interval analysis, heart rate (RR) variation in response to deep breathing and standing, and ABPI were analysed in 192 patients with non-insulin dependent diabetes. Cardiac death was the primary end point. Results: Mean (SD) follow up was 12.7 (3.2) years (range 1.2–17.1 years). There were 48 deaths, of which 26 were cardiac. QTc and QTD were individually significant predictors of cardiac mortality throughout the follow up period (p < 0.001). The predictability of QT parameters was superior to the predictability of ABPI and RR interval analysis. Temporal changes in QT parameters showed that the mean absolute QT parameter was a significant predictor of cardiac death (p < 0.001), whereas an intraindividual change in QT parameter over time was not predictive. Conclusion: QT abnormalities seem to exist at the point of diagnosis of diabetes and do not appear to change between then and the subsequent cardiac death. Furthermore, the analysis of QT interval is superior to ABPI and the RR interval in identifying diabetic patients at high risk of cardiac death.

The morning surge in blood pressure and heart rate is dependent on levels of physical activity after waking.

Objective To define the influence of morning physical activity levels on the magnitude of the morning surge in blood pressure and heart rate. Design and methods Blood pressure and physical activity were simultaneously recorded in 420 patients by 24-h monitor and actigraphy. The morning surge was defined as the difference between mean blood pressure and heart rate values in the 4-h periods before and after waking; the trough-to-peak surge in blood pressure was also calculated. These values were regressed on the difference in mean (log transformed) physical activity for the same two periods. The analysis was adjusted for covariates, including age, sex, clinic blood pressure and use of antihypertensive medication, in a multiple linear regression. Results The mean morning surges in blood pressure and heart rate were 23/15(± 13/10) mmHg and 17(± 10) beats/min, respectively. The geometric mean increase in physical activity after waking was 33(± 1.5) units. The magnitudes of the morning surge in systolic blood pressure, diastolic blood pressure and heart rate were all significantly and positively correlated with the difference in mean physical activity before and after waking (P < 0.005). Greater clinic blood pressure was significantly associated with a greater morning surge in blood pressure on physical activity (P < 0.0005). Conclusions The magnitude of the morning surge is significantly associated with the level of physical activity in the hours after waking. Physical activity should be taken into account when the results of ambulatory blood pressure monitoring are interpreted.

C-type natriuretic peptide levels in cor pulmonale and in congestive heart failure.

BACKGROUND--C-type natriuretic peptide (CNP) is a recent addition to the family of natriuretic peptides which includes atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Whilst the levels of ANP and BNP are increased in conditions such as congestive heart failure and cor pulmonale, abnormal levels of CNP in these conditions have not been reported. METHODS--Plasma levels of CNP were measured by specific radioimmunoassay in 12 young normal controls, 12 elderly normal controls, 12 patients with NYHA grade III-IV congestive heart failure, and in 16 patients with hypoxaemic cor pulmonale. RESULTS--Mean (SE) plasma levels of CNP were similar in young normal controls (0.46(0.03) pmol/l), elderly normal controls (0.43(0.05) pmol/l), and in patients with congestive heart failure (0.33(0.2) pmol/l). In patients with cor pulmonale, however, plasma levels of CNP were raised (1.39(0.27) pmol/l) 3.2-fold compared with age-matched controls. CONCLUSIONS--In cor pulmonale the increased plasma levels of CNP were not as great as the previously observed increases in levels of ANP (5.6-fold) or BNP (18.5-fold) in comparable patients. CNP may therefore be less important than ANP or BNP as a circulating counter-regulatory peptide in conditions of overactivity of the renin angiotensin system.

Abnormal myocardial repolarisation in response to hypoxaemia and fenoterol.

BACKGROUND--Prolongation of the QTc interval has been associated with cardiac dysrhythmias and sudden death. QTc dispersion (interlead variability in QTc interval) has recently been proposed as being a more sensitive marker of repolarisation abnormalities and shown to be a more specific index of arrhythmia risk. Although hypoxaemia and fenoterol have previously been shown to prolong the QTc interval, this does not reflect regional myocardial repolarisation abnormalities. METHODS--Electrophysiological effects were measured at baseline and after 30 minutes steady state hypoxaemia at an arterial oxygen saturation (SaO2) of 75-80% (study 1) and at baseline then 30 minutes after inhaled fenoterol 2.4 mg (study 2). From the ECG, lead II corrected QT interval (QTc) and overall corrected QT dispersion were measured using a computer linked digitising tablet according to standard criteria. RESULTS--QTc dispersion was increased during hypoxia compared with baseline values (mean (SE) 69 (6) ms v 50 (5) ms) and after fenoterol compared with baseline (79 (13) v 46 (4) ms), respectively. There was also an increase in QTc interval and heart rate after fenoterol (493 (23) v 420 (6) ms and 98 (3) v 71 (6) bpm, respectively). The heart rate was increased during hypoxaemia compared with baseline (78 (3) v 64 (2) bpm), but no change occurred in the QTc interval. CONCLUSIONS--Both hypoxaemia and fenoterol cause myocardial repolarisation abnormalities in man in terms of increased QTc dispersion, but only fenoterol increased the QTc interval. This may be relevant in the aetiology of arrhythmias in patients with acute severe asthma where beta agonist therapy and hypoxaemia coexist.

Renin–Angiotensin–Aldosterone System Inhibitors in Heart Failure

Heart failure (HF) is a very common condition that, despite advances in treatment, carries significant morbidity and mortality. Although there is good evidence for the treatment of HF with reduced ejection fraction (HFrEF), the treatment for HF with preserved ejection fraction (HFpEF) is not well defined. The renin–angiotensin–aldosterone system (RAAS) has been shown to be an effective target in the treatment of HFrEF using angiotensin‐converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone blockade, although the evidence in HFpEF is less clear. This review aims to look first at the evidence for these drugs, and second at the newer drugs that act on the RAAS, namely, direct renin inhibitors, neutral endopeptidase inhibitors, vasopeptidase inhibitors, and angiotensin receptor blockers.

Left ventricular hypertrophy: reduction of blood pressure already in the normal range further regresses left ventricular mass

Objective: Left ventricular hypertrophy (LVH) confers high cardiovascular risk. Regression of LVH reduces risk. Patients with blood pressure in the normal range and LVH are common. We investigated whether further reduction in blood pressure would further regress LVH. Methods: 51 subjects with blood pressure in the normal range and echocardiographic left ventricular hypertrophy were randomly assigned to active treatment (antihypertensive medication) or placebo in a ratio of 2:1. The aim was to maintain office systolic blood pressure at 10 mm Hg less than baseline in the active arm and at baseline level in the placebo arm. Cardiac magnetic resonance imaging was used to measure change in left ventricular mass index over 12 months. Results: 35 subjects completed the study (active 23: placebo 12). Average mean baseline office systolic blood pressure was 122 (SD 9) mm Hg in the active group and 124 (9) mm Hg in the placebo group (p = 0.646). The mean baseline left ventricular mass index was 65.88 (11.87) g/m2 in the active group and 59.16 (11.13) g/m2 in the placebo group (p = 0.114). The mean difference between baseline and end of study office systolic blood pressure was −9.33 (8.56) mm Hg in the active group and −0.08 (9.27) mm Hg in the placebo group (p = 0.007). The mean change in left ventricular mass index was −4.68 (7.31) g/m2 in the active group and +1.97 (6.68) g/m2 in the placebo group (p = 0.014). Conclusions: Reduction in office systolic blood pressure, already in the normal range, of approximately 9 mm Hg, leads to a reduction in left ventricular mass. Further work is required to see if this also leads to a reduction in cardiovascular events. Trial registration number: ISRCTN48331653.