Beta-blockers and mechanical dyssynchrony in heart failure assessed by radionuclide ventriculography.

BACKGROUND: Radionuclide ventriculography (RNVG) can be used to quantify mechanical dyssynchrony and may be a valuable adjunct in the assessment of heart failure with reduced ejection fraction (HFrEF). The study aims to investigate the effect of beta-blockers on mechanical dyssynchrony using novel RNVG phase parameters. METHODS: A retrospective study was carried out in a group of 98 patients with HFrEF. LVEF and dyssynchrony were assessed pre and post beta-blockade. Dyssynchrony was assessed using synchrony, entropy, phase standard deviation, approximate entropy, and sample entropy from planar RNVG phase images. Subgroups split by ischemic etiology were also investigated. RESULTS: An improvement in dyssynchrony and LVEF was measured six months post beta-blockade for both ischemic and non-ischemic groups. CONCLUSIONS: A significant improvement in dyssynchrony and LVEF was measured post beta-blockade using novel measures of dyssynchrony.

Radionuclide ventriculography phase analysis for risk stratification of patients undergoing cardiotoxic cancer therapy.

BACKGROUND: Accurate diagnostic tools to identify patients at risk of cancer therapy-related cardiac dysfunction (CTRCD) are critical. For patients undergoing cardiotoxic cancer therapy, ejection fraction assessment using radionuclide ventriculography (RNVG) is commonly used for serial assessment of left ventricular (LV) function. METHODS: In this retrospective study, approximate entropy (ApEn), synchrony, entropy, and standard deviation from the phase histogram (phase SD) were investigated as potential early markers of LV dysfunction to predict CTRCD. These phase parameters were calculated from the baseline RNVG phase image for 177 breast cancer patients before commencing cardiotoxic therapy. RESULTS: Of the 177 patients, 11 had a decline in left ventricular ejection fraction (LVEF) of over 10% to an LVEF below 50% after treatment had commenced. This patient group had a significantly higher ApEn at baseline to those who maintained a normal LVEF throughout treatment. Of the parameters investigated, ApEn was superior for predicting the risk of CTRCD. Combining ApEn with the baseline LVEF further improved the discrimination between the groups. CONCLUSIONS: The results suggest that RNVG phase analysis using approximate entropy may aid in the detection of sub-clinical LV contraction abnormalities, not detectable by baseline LVEF measurement, predicting a subsequent decline in LVEF.

WITHDRAWN: Secondary Harmonic Imaging Overestimates Left Ventricular Mass Compared to Fundamental Echocardiography.

The publisher regrets that this was an accidental duplication of an article that has already been published in Eur. J. Echocardiogr., 4 (2003) 178-181, . The duplicate article has therefore been withdrawn.

Effects of acute angiotensin II type 1 receptor antagonism and angiotensin converting enzyme inhibition on plasma fibrinolytic parameters in patients with heart failure.

BACKGROUND: Angiotensin converting enzyme (ACE) inhibition after myocardial infarction is associated with an improvement in plasma fibrinolytic parameters. The aim of the present study was to determine whether acute ACE inhibition and angiotensin II type 1 (AT1) receptor antagonism have similar effects in patients with heart failure. METHODS AND RESULTS: Twenty patients with moderately severe chronic heart failure received enalapril 10 mg and losartan 50 mg on 2 separate occasions in a single-blind, randomized, crossover design. Plasma tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) antigen and activity were measured at baseline and 6 hours after the dose. Acute administration of losartan but not of enalapril reduced plasma t-PA (11%; P=0.003) and PAI-1 (38%; P<0.001) antigen concentrations, which was associated with increases in t-PA (29%; P=0.03) and decreases in PAI-1 (48%; P=0.01) activity. Changes in plasma fibrinolytic parameters were more marked during losartan treatment (P<0.02), with a 3-fold greater reduction in plasma PAI-1 antigen concentrations (P<0.05). CONCLUSIONS: Acute AT1 antagonism in patients with heart failure is associated with a significant improvement in plasma fibrinolytic parameters that is greater than during ACE inhibition. These beneficial effects of AT1 antagonism and ACE inhibition would therefore appear to be mediated principally through suppression of angiotensin II.

Measurement of parasympathetic activity from 24-hour ambulatory electrocardiograms and its reproducibility and sensitivity in normal subjects, patients with symptomatic myocardial ischemia, and patients with diabetes mellitus.

The parasympathetic nervous system plays a major role in the pathophysiology of many cardiovascular disease, particularly in modulating myocardial electrical stability. Measurements of heart rate variability have been widely used to assess parasympathetic activity. The reproducibility of measurements obtained from 24-hour ambulatory electrocardiograms has not been well documented. We have developed a technique for measuring parasympathetic activity from clinical quality 24-hour ambulatory electrocardiograms by counting beat-to-beat increases in RR interval that are > 50 ms. To determine the reproducibility and sensitivity of our technique, we analyzed repeated 24-hour electrocardiograms of 173 subjects (19 normal subjects, 67 patients with ischemic heart disease, and 87 diabetics) followed up over periods of 2 to 16 weeks. In all subject groups, mean values for repeated measurements were virtually identical. Measurements were stable in all 3 groups throughout the course of the study, as assessed by intraclass correlation coefficients. This technique is sensitive enough to detect relatively small changes in parasympathetic activity in subjects, as demonstrated by the calculated Bland and Altman coefficients of repeatability. Reproducibility and sensitivity of our technique are particularly good in normal subjects and in patients with ischemic heart disease. The results obtained with this technique imply that other related measurements of parasympathetic activity will show similar excellent short- and long-term reproducibility and sensitivity.

Regulation of peripheral vascular tone in patients with heart failure: contribution of angiotensin II.

OBJECTIVE: To determine directly the contribution of angiotensin II to basal and sympathetically stimulated peripheral arteriolar tone in patients with heart failure. DESIGN: Parallel group comparison. SUBJECTS: Nine patients with New York Heart Association grade II-IV chronic heart failure, and age and sex matched controls. INTERVENTIONS: Forearm plethysmography, lower body negative pressure, local intra-arterial administration of losartan, angiotensin II, and noradrenaline, and estimation of plasma hormone concentrations. MAIN OUTCOME MEASURES: Forearm blood flow responses, plasma hormone concentrations. RESULTS: Baseline blood pressure, heart rate, and forearm blood flow did not differ between patients and controls. In comparison with the non-infused forearm, losartan did not affect basal forearm blood flow (95% confidence interval -5.5% to +7.3%) or sympathetically stimulated vasoconstriction in controls. However, the mean (SEM) blood flow in patients increased by 13(5)% and 26(7)% in response to 30 and 90 micrograms/min of losartan respectively (p < 0.001). Lower body negative pressure caused a reduction in forearm blood flow of 20(5)% in controls (p = 0.008) and 13(5)% (p = 0.08) in patients (p = 0.007, controls v patients). Blood flow at 90 micrograms/min of losartan correlated with plasma angiotensin II concentration (r = 0.77; p = 0.03). Responses to angiotensin II and noradrenaline did not differ between patients and controls. CONCLUSIONS: Losartan causes acute local peripheral arteriolar vasodilation in patients with heart failure but not in healthy control subjects. Endogenous angiotensin II directly contributes to basal peripheral arteriolar tone in patients with heart failure but does not augment sympathetically stimulated peripheral vascular tone.

Effects of digoxin on time domain measures of heart rate variability in patients with stable chronic cardiac failure: withdrawal and comparison group studies.

The effect on heart rate variability of adding digoxin to a diuretic and ACE inhibitor was studied in patients with chronic stable cardiac failure. Digoxin was found to increase heart rate variability, especially those measures of heart rate variability thought to represent parasympathetic activity. The withdrawal of digoxin led to a decrease in heart rate variability to pre-treatment levels. Whilst digoxin in standard doses does not alter prognosis in chronic cardiac failure, it does have potentially beneficial neurohumoral effects. If the increase in heart rate variability, which represents beneficial neurohumoral modulation, can be divorced from the potentially detrimental effects, perhaps by using smaller doses, then there may be a role for digoxin in the treatment of chronic cardiac failure.

Optimising direct access ECHO referral in suspected heart failure.

The objective was to prospectively validate a method of increasing the sensitivity, specificity and negative predictive value of a normal ECG in the exclusion of left ventricular systolic dysfunction by the addition of clinical history. We performed a prospective three year study of all referrals to our direct access ECHO service for assessment of LV function. The ECG was reported blind of the result of the ECHO, history of MI or not was noted, and result of the ECHO predicted. Over three years 416 patients were assessed for the presence or absence of left ventricular systolic dysfunction and consequent changes in clinical management. A total of 320(77%) of patients referred with suspected left ventricular dysfunction were found to have normal left ventricular function. Of the 250(60%) patients treated prior to referral for assessment, 183(73%) were treated inappropriately. The combination of a normal ECG and a negative history of myocardial infarction had a sensitivity of 98% and a negative predictive value of 99% in the assessment of LV function. This was an improvement over a normal ECG alone. Our study shows that diagnosis and treatment of heart failure in the community remains sub-optimal. The combination of a normal ECG and no previous history of myocardial infarction is shown to be a sensitive and accurate predictor of normal left ventricular function. If adopted by general practitioners this would be a valuable method of optimising the use of echocardiography in patients with suspected left ventricular dysfunction.

Limited clinical utility of CT coronary angiography in a district hospital setting.

BACKGROUND: Studies have demonstrated considerable accuracy of multi-slice CT coronary angiography (MSCT-CA) in comparison to invasive coronary angiography (I-CA) for evaluating coronary artery disease (CAD). The extent to which published MSCT-CA accuracy parameters are transferable to routine practice beyond high-volume tertiary centres is unknown. AIM: To determine the accuracy of MSCT-CA for the detection of CAD in a Scottish district general hospital. DESIGN: Prospective study of diagnostic accuracy. METHOD: One hundred patients with suspected CAD recruited from two Glasgow hospitals underwent both MSCT-CA (Philips Brilliance 40 × 0.625 collimation, 50-200 ms temporal resolution) and I-CA. Studies were reported by independent, blinded radiologists and cardiologists and compared using the AHA 15-segment model. RESULTS: Of 100 patients [55 male, 45 female, mean (SD) age 58.0 (10.7) years], 59 and 41% had low-intermediate and high pre-test probabilities of significant CAD, respectively. Mean (SD) heart rate during MSCT-CA was 68.8 (9.0) bpm. Fifty-seven per cent of patients had coronary artery calcification and 35% were obese. Patient prevalence of CAD was 38%. Per-patient sensitivity, specificity, positive and negative (NPV) predictive values for MSCT-CA were 92.1, 47.5, 52.2 and 90.6%, respectively. NPV was reduced to 75.0% in the high pre-test probability group. Specificity was compromised in patients with sub-optimally controlled heart rates, calcified arteries and elevated BMI. CONCLUSION: Forty-Slice MSCT-CA has a high NPV for ruling out significant CAD when performed in a district hospital setting in patients with low-intermediate pre-test probability and minimal arterial calcification. Specificity is compromised by clinically appropriate strategies for dealing with unevaluable studies. Effective heart rate control during MSCT-CA is imperative. National guidelines should be utilized to govern patient selection and direct MSCT-CA reporter training to ensure quality control.

Secondary harmonic imaging overestimates left ventricular mass compared to fundamental echocardiography.

AIMS: The significance of left ventricular hypertrophy in hypertension is well documented, being an independent risk factor for cardiovascular morbidity and mortality. Normal values for left ventricular mass and partition values for left ventricular hypertrophy come from measurements obtained by fundamental echocardiography. Secondary harmonic imaging improves definition of cardiac borders. We hypothesise that this overestimates left ventricular mass compared to fundamental imaging. METHODS AND RESULTS: Thirty patients had four parasternal long-axis M-modes performed, two using 1.7 mHz output frequency, receiving at two octaves higher and two using fixed frequency of 2.5 mHz (fundamental imaging). Absolute left ventricular mass and left ventricular mass index were calculated for each modality. Intra-observer variability was <7%. Range on fundamental imaging was 54-264 g/m2 compared to 80-293 g/m2 on secondary harmonic imaging. Mean left ventricular mass index for the group was 118 g/m2 (fundamental imaging) vs 147 g/m2, P<0.001. Twenty-nine of 30 patients had higher left ventricular mass index on secondary harmonic imaging compared to fundamental imaging. Left ventricular mass index was an average of 26% higher on secondary harmonic imaging, range (-7 to 65%) corresponding to average absolute left ventricular mass difference of 55 g. Eleven of 30 patients had left ventricular hypertrophy on fundamental imaging and 17/30 on secondary harmonic imaging. CONCLUSION: Secondary harmonic imaging overestimates left ventricular mass index compared to fundamental imaging. Normal left ventricular mass index range is based on equations using fundamental imaging measurements. Management decisions and prognostic implications made on the basis of raised left ventricular mass index using secondary harmonic imaging should be done so with caution.

Cardiac involvement in Wegener's granulomatosis.

Wegener's granulomatosis is a systemic inflammatory disorder of unknown aetiology. The protean clinical presentations depend on the organ(s) involved and the degree of progression from a local to a systemic arteritis. The development of serological tests (antieutrophil cytoplasmic antibodies) allows easier diagnosis of a disease whose incidence is increasing. This is particularly helpful where the presentation is not classic--for example "overlap syndromes"--or where the disease presents early in a more localised form. This is true of cardiac involvement, which is traditionally believed to be rare, but may not be as uncommon as has hitherto been thought (< or = 44%). This involvement may be subclinical or the principal source of symptoms either in the form of localised disease or as part of a systemic illness. Pericarditis, arteritis, myocarditis, valvulitis, and arrhythmias are all recognised. Wegener's granulomatosis should therefore be considered in the differential diagnosis of any non-specific illness with cardiac involvement. This includes culture negative endocarditis, because Wegener's granulomatosis can produce systemic upset with mass lesions and vasculitis. Echocardiography and particularly transoesophageal echocardiography can easily identify and delineate cardiac and proximal aortic involvement and may also be used to assess response to treatment.