Informed consent-patients' understanding of risk.

AIMS: The central concept of informed consent is communication of the chance of a successful outcome. The risks and benefits are probabilistic concepts derived from populations; they do not map with any certainty to the individual. We tested patients' comprehension of basic probability concepts that are needed for informed consent. METHODS: Patients (n=478) completed five questions designed to test risk estimates that are relevant to informed consent. The questions posed non-medical scenarios to avoid patients associating them with their clinical care. The questionnaire was in English and was only offered to patients whose nurse felt that they had sufficient English literacy to understand the questions. RESULTS: Out of a possible total of five correct answers, Asian patients scored lowest, and significantly less than Pakeha/Europeans (average total score 2.6±1.7 vs 3.6±1.4, p<0.001, 95% confidence interval 0.5 to 1.38). The total score for Maori/Pasifika was intermediate (3.2±1.4), yet they had the lowest deprivation index. This discordant finding may be due to poorer English literacy among Asian participants. On multiple linear regression, Asian ethnicity and advancing age were the independent predictors of a low score. Socio-economic deprivation decile and sex were not. CONCLUSIONS: When answering questions constructed according to best practice, many (but not all) patients have reasonable risk comprehension. Further improvement could target older patients, those of Asian ethnicity and probably all patients where English is a second language. Liberal use of interpreters is suggested.

Signal-to-noise of linear and volume measures of left ventricular and left atrial size.

BACKGROUND: Serial echocardiographic assessments are common in clinical cardiology, e.g., for timing of intervention in mitral and aortic regurgitation. When following patients with serial echocardiograms, each new measurement is a combination of true change and confounding noise. The current investigation compares linear chamber dimensions with volume estimates of chamber size. The aim is to assess which measure is best for serial echocardiograms, when the ideal parameter will be sensitive to change in chamber size and have minimal spurious variation (noise). We present a method that disentangles true change from noise. Linear regression of chamber size against elapsed time gives a slope, being the ability of the method to detect change. Noise is the scatter of individual points away from the trendline, measured as the standard error of the slope. The higher the signal-to-noise ratio (SNR), the more reliably a parameter will distinguish true change from noise. METHODS: LV and LA parasternal dimensions and apical biplane volumes were obtained from serial clinical echocardiogram reports. Change over time was assessed as the slope of the linear regression line, and noise was assessed as the standard error of the regression slope. Signal-to-noise ratio is the slope divided by its standard error. RESULTS: The median number of LV studies was 5 (4-11) for LV over a mean duration of 5.9 ± 3.0 years in 561 patients (diastole) and 386 (systole). The median number of LA studies was 5 (4-11) over a mean duration of 5.3 ± 2.0 years in 137 patients. Linear estimates of LV size had better signal-to-noise than volume estimates (p < 0.001 for diastolic and p = 0.035 for systolic). For the left atrium, the difference was not significant (p = 0.214). This may be due to sample size; the effect size was similar to that for LV systolic size. All three parameters had a numerical value of signal-to-noise that favoured linear dimensions over volumes. CONCLUSION: Linear measures of LV size have better signal-to-noise than volume measures. There was no difference in signal-to-noise between linear and volume measures of LA size, although this may be a Type II error. The use of regression lines may be better than relying on single measurements. Linear dimensions may clarify whether changes in volumes are real or spurious.

Associations between the home yard and preschoolers' outdoor play and physical activity.

Objectives and importance of study: Young children's outdoor play mostly occurs within the home-yard space, yet the influence of the home yard on preschoolers' outdoor play and physical activity is poorly understood. We investigated the relationships between home-yard features and home-based outdoor play and physical activity in preschoolers (2-5 years old). STUDY TYPE: Cross-sectional observational study. METHODS: The PLAY Spaces and Environments for Children's Physical Activity (PLAYCE) study (2015-2017) included 1596 children aged 2-5 years attending early childhood education and care (ECEC) services throughout metropolitan Perth, Western Australia. In this study, a subsample of 224 parents from the PLAYCE study completed an online questionnaire about home-yard features (yard size, lawn quality, natural features, fixed and portable play equipment, and flowers and vegetables/herbs). Accelerometers measured the duration of preschoolers' moderate-vigorous physical activity (MVPA) on non-ECEC days. Parent-reported outdoor play at home, sociodemographic factors and social environment factors were collected via the PLAYCE parent survey. Multiple linear regression models were used to determine associations between home-yard features and preschoolers' outdoor play and physical activity. RESULTS: Children spent 68.9 (SD 2.2) minutes playing outdoors in the home yard per day, and 93.3 (SD 37.1) minutes in MVPA per day on non-ECEC days. After adjusting for child and parent factors, home-yard features positively associated with outdoor play included yard size, lawn quality, number of types of fixed and portable play equipment, natural features and play areas (all p ≤ 0.05). When all significant home-yard features were placed in a model, only the number of types of fixed play equipment was positively associated with minutes of outdoor play per day (ß = 5.3, p < 0.001). After adjusting for sociodemographic factors, the number of types of portable play equipment in the yard was positively associated with MVPA minutes per day (ß = 2.16, p = 0.019); however, this became nonsignificant after further adjusting for social environment factors. CONCLUSIONS: Features of the home-yard physical environment were positively associated with preschoolers' outdoor play and physical activity. Each additional type of fixed play equipment present was associated with an additional 5 minutes of outdoor play per day. These findings suggest that the home-yard space has the potential to facilitate increased outdoor play in young children. Further research is warranted to explore causal relationships between home-yard attributes and young children's outdoor play and physical activity.

An uncommon cause of myocardial infarction.

A 73 year-old lady with hypertension and chronic atrial fibrillation (AF) developed chest pain followed by ventricular fibrillation (VF) cardiac arrest. Her electrocardiogram post-cardioversion revealed inferior ST-elevation myocardial infarction (MI). Her coronary arteries were angiographically normal. Contrast-enhanced cardiac magnetic resonance(CE-CMR) demonstrated both an inferior subendocardial infarction and left atrial (LA) appendage thrombus suggesting cardioembolism as the most likely cause of her presentation.

Prevalence and prognostic significance of left ventricular dysfunction in patients presenting acutely with atrial fibrillation.

CONDENSED ABSTRACT: The prevalence and prognostic importance of CM occurring as a consequence of AF is poorly defined. This study investigated the incidence of CM in patients with AF, its clinical features and long-term outcomes. We demonstrated that CM is common in patients presenting acutely with newly diagnosed rapid AF, and carries a worse long-term prognosis. Systolic dysfunction was reversible in an important proportion of patients, suggesting a greater prevalence of rate-related CM in AF than has previously been postulated. This underscores the importance of appropriate rhythm management strategies and repeat imaging studies. BACKGROUND: Atrial fibrillation (AF) may precipitate LV dysfunction, potentially leading to cardiomyopathy (CM). The prevalence and prognostic importance of CM occurring as a consequence of AF is poorly defined. We investigated the incidence of CM in patients with AF, its clinical features and long-term outcomes. METHODS: We reviewed 292 consecutive patients (average age 72 +/- 13yrs) presenting acutely with AF and tachycardia over a 3 year period from June 2004. Clinical details were obtained from medical records. CM was defined as ejection fraction (EF)

Characteristics and prognostic importance of myocardial fibrosis in patients with dilated cardiomyopathy assessed by contrast-enhanced cardiac magnetic resonance imaging.

INTRODUCTION: Dilated cardiomyopathy (DCM) is associated with significant morbidity and mortality. Contrast-enhanced cardiac MRI (CE-CMR) can detect potentially prognostic myocardial fibrosis in DCM. We investigated the role of CE-CMR in New Zealand patients with DCM, both Maori and non-Maori, including the characteristics and prognostic importance of fibrosis. METHODS: One hundred and three patients (mean age 58 ± 13, 78 male) referred for CMR assessment of DCM were followed for 660 ± 346 days. Major adverse cardiac events (MACE) were defined as death, infarction, ventricular arrhythmias or rehospitalisation. CE-CMR used cines for functional analysis, and delayed enhancement to assess fibrosis. RESULTS: Myocardial fibrosis was present in 30% of patients, the majority of which was mid-myocardial (63%). Volumetric parameters were similar in patients with or without fibrosis. At 2 years patients with fibrosis had an increased rate of MACE (HR = 0.77, 95% CI 0.3-2.0). Patients with full thickness or subendocardial fibrosis had the highest MACE, even in the absence of CAD). More Maori had fibrosis on CE-CMR (40% vs. 28% for non-Maori), and the majority (75%) was mid-myocardial. Maori and non-Maori had similar outcomes (25% vs. 24% with events during follow-up). CONCLUSIONS: DCM patients frequently have myocardial fibrosis detected on CE-CMR, the majority of which is mid-myocardial. Fibrosis is associated with worse outcome in the medium term. The information obtained using CE-CMR in DCM may be of incremental clinical benefit.

A modeling intervention in heart failure.

BACKGROUND: Peak oxygen uptake (VO(2)) testing is commonly used to assess chronic heart failure (CHF) patients' exercise tolerance. The test requires maximal effort; however, many participants have low confidence (self-efficacy) to perform optimally. PURPOSE: This randomized controlled trial examined the effectiveness of a modeling intervention to increase Peak VO(2) (PVO(2)) and self-efficacy in people diagnosed with CHF. METHODS: Twenty participants with a diagnosis of CHF were randomized to either an intervention (modeling DVD) or a control group. Both groups completed a measure of self-efficacy prior to performing two PVO(2) tests, each separated by 7 days. After completing the first test (T1) the intervention group watched a 10-min coping model DVD. All participants returned 1 week later (T2) to complete identical study procedures. RESULTS: Analysis of covariance results showed that compared with the participants in the control group, those assigned to the modeling intervention had higher PVO(2) at T2, F (1, 19) = 4.38, p = 0.05, eta (2) = 0.21 and self-efficacy, F (1, 19) = 5.80, p < 0.05, eta (2) = 0.25. Only partial support was found for change in self-efficacy mediating treatment outcome (PVO(2)). CONCLUSIONS: Watching a modeling video is associated with increased PVO(2) and self-efficacy. These results have implications for testing patients in a clinical setting to maximize exercise tolerance test results.

Reliability of echocardiographic indices of dyssynchrony.

BACKGROUND: Echocardiographic indices of dyssynchrony are increasingly used to select candidates for cardiac resynchronization therapy. For widespread screening of heart failure patients, such variables need to be comparable when evaluated by different operators using different equipment. OBJECTIVE AND METHODS: To evaluate the reproducibility and obtainability of echocardiographic indices of mechanical dyssynchrony, we studied 40 subjects stratified according to QRS morphology and systolic function. Two echocardiograms were performed on each patient by different sonographers on different machines and each study was analyzed by two observers. RESULTS: All blood-pool and tissue Doppler indices of dyssynchrony were obtainable in over 97% of cases. Blood-pool Doppler measures were the most reproducible indices of intraventricular dyssynchrony (aortic ejection delay) and interventricular dyssynchrony (aortopulmonary difference in ejection delay). For annular tissue Doppler delays, the time to peak velocity was consistently more reproducible than the time to velocity onset. CONCLUSION: Differences in the reliability of echocardiographic indices may affect their suitability as screening tests for dyssynchrony.

Ultrasound-guided venous access for permanent pacemaker leads.

BACKGROUND: Existing methods of venous access for permanent pacemaker leads have disadvantages. We documented learning times for ultrasound-guided lead implantation and compared them with cephalic venotomy technique. METHODS: Two implanters learnt ultrasound-guided technique by implanting consecutive pacemaker patients. When procedural times stabilized, we reverted to our normal cephalic approach. We measured lead placement time and screening time from skin incision until all leads were placed in superior vena cava were measured. RESULTS: Initial strategy adopted was ultrasound for 60, then cephalic for 38 patients. There were no significant differences between groups in baseline characteristics or number of leads implanted. Lead placement and screening times were significantly shorter for ultrasound, despite inclusion of all learning cases. There was a high success rate for both strategies (88% ultrasound, 87% cephalic). There was significantly greater use of pressure dressings with ultrasound, but no difference in pocket hematoma or pneumothorax. There was a trend for more predictable lead implant times with ultrasound and fluoroscopy times were shorter and more predictable. Independent predictors of lead placement time were body mass index, operator, initial strategy (ultrasound vs cephalic), and procedure number. CONCLUSION: Ultrasound-guided venepuncture for placement of permanent pacing leads is quick to learn and achieves faster lead placement times with shorter and more predictable fluoroscopy time when compared with the cephalic venotomy technique.

Effectiveness of manual pressure hemostasis following transfemoral coronary angiography in patients on therapeutic warfarin anticoagulation.

We evaluated the effectiveness of manual pressure hemostasis after transfemoral coronary angiography in patients on therapeutic warfarin anticoagulation (international normalized ratio [INR] 2.0 to 3.0) compared with discontinuing warfarin > or =48 hours before the procedure (INR <2.0). There was a low incidence of small hematomas with either strategy (no significant difference) and no major vascular complications. No prolonged hospital stay due to an access site complication was observed, and no thromboembolic events occurred. In conclusion, transfemoral coronary angiography appears to be safe in patients on warfarin with an INR of 2.0 to 3.0).

Polycythaemia vera presenting as ST-elevation myocardial infarction.

A case of ST-elevation myocardial infarction as the first presentation of polycythaemia vera is described. The discussion summarises the evidence for the safety and efficacy of contemporary ST-elevation treatment strategies in the setting of polycythaemia vera.

Atrial pacing should be used more frequently in sinus node disease.

BACKGROUND: Single lead atrial (AAI(R)) pacing for sick sinus syndrome provides physiological pacing and is less expensive than a dual chamber system. Compared with ventricular-based pacing, it maintains the normal cardiac depolarization sequence, is associated with less atrial fibrillation and heart failure, and avoids pacemaker syndrome. We sought whether it is possible to select patients for AAI(R) pacing with a low likelihood of subsequent ventricular pacing, and whether this approach was cost-effective. METHODS: A retrospective review was conducted of AAI(R) pacemaker implantations. Patients requiring a further procedure for insertion of a ventricular lead (for DDD(R) or VVI(R) pacing) were compared with those who remained atrially paced. RESULTS: 2.7% (117 of 4,366) of implants were AAI(R), compared with less than 1% overall for New Zealand and Australia. During follow-up of 3.5 (2.3, 7.7) years, insertion of a ventricular lead was required in 14 (12%), and was more likely in those with pre-existing PR interval >0.20 seconds (odds ratio 7.8, P = 0.003) or left bundle branch block (LBBB, odds ratio 17, P = 0.037). Right bundle branch block, left anterior fascicular block, or history of paroxysmal atrial fibrillation were not more frequent in the group requiring ventricular pacing, and preimplantation Wenckebach point was not different. The most efficient strategy was initial AAIR implantation in all except those with LBBB or PR interval >0.20 seconds. Compared with routine DDDR implantation, cost was reduced by 20%, with a 1.4% annual incidence of further procedures. CONCLUSION: AAIR is the appropriate pacing choice for sick sinus syndrome without LBBB or PR interval >0.20 seconds.

An evaluation of the use of new Doppler methods for detecting longitudinal function abnormalities in a pacing-induced heart failure model.

BACKGROUND: Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. PURPOSE AND METHODS: We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS: With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P <.0001). In contrast to the mitral inflow velocities, mitral annulus early diastolic velocity decreased steadily (12.3-7.3 cm/s) resulting in a dramatic decrease in mitral annulus early/late (1.22-0.57) diastolic velocity with no tendency toward pseudonormalization. The color M-mode Doppler flow propagation velocity also showed significant steady decrease (57-24 cm/s) throughout the pacing period. Multiple regression analysis chose mitral annulus systolic velocity (r = 0.895, P <.0001) and propagation velocity (r = 0.782, P <.0001) for the most important factor predicting LV systolic and diastolic function, respectively. CONCLUSIONS: Doppler tissue echocardiography and color M-mode Doppler flow could evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.