James Cameron

Brachial Blood Pressure But Not Carotid Arterial Waveforms Predict Cardiovascular Events in Elderly Female Hypertensives

Central arterial waveforms and related indices of large artery properties can be determined with relative ease. This would make them an attractive adjunct in the risk stratification for cardiovascular disease. Although they have been associated with some classical risk factors and the presence of coronary disease, their prospective value in predicting cardiovascular outcomes is unknown. The present study determined the relative predictive value for cardiovascular disease–free survival of large artery properties as compared with noninvasive brachial blood pressure alone in a population of elderly female hypertensive subjects. We measured systemic arterial compliance, central systolic pressure, and carotid augmentation index in a subset of female participants in the Second Australian National Blood Pressure Study (untreated blood pressure 169/88±12/8 mm Hg). There were a total of 53 defined events during a median of 4.1 years of follow-up in 484 women with complete measurements. Although baseline blood pressures at the brachial artery predicted cardiovascular disease–free survival (hazard ratio [HR], 2.3; 95% CI, 1.3 to 4.1 for pulse pressure ≥81 versus <81 mm Hg; P=0.01), no such relation was found for carotid augmentation index (HR, 0.80; 95% CI, 0.44 to 1.44; P value not significant) or systemic arterial compliance (HR, 1.25; 95% CI, 0.72 to 2.16; P value not significant). Blood pressure, but not noninvasively measured central arterial waveforms, predict outcome in the older female hypertensive patient. Thus, blood pressure measurement alone is superior to measurement of arterial waveforms in predicting outcome in this group.

Performance monitoring in interventional cardiology: application of statistical process control to a single-site database

AIMSnGraphical Statistical Process Control (SPC) tools have been shown to promptly identify significant variations in clinical outcomes in a range of health care settings, but as yet have not been widely applied to performance monitoring in percutaneous coronary intervention (PCI). We explored the application of these techniques to a prospective PCI registry at a single site.nnnMETHODS AND RESULTSnBaseline clinical and procedural data along with one and twelve month major adverse cardiac event (MACE) details were prospectively collected in relation to 2,697 consecutive PCI procedures (2,417 patients) performed between the 1st January 2003 and the 31st December 2007. We investigated outcome measures which were both clinically relevant and occurred at a sufficient frequency (>1%) to allow valid application of SPC techniques, and found procedural and lesion failure, major postprocedural complications, and one and 12 month MACE to be suitable endpoints. Cumulative Sum (CUSUM) charts, Variable Life-Adjusted Display (VLAD) charts and Funnel Plots were employed in combination to evaluate both group and individual performance on a near real time basis. We found that the use of these charts provided complimentary prospective audit of clinical performance to identify variations in group and individual operator performance and to clarify these as either systemic or individual operator-related. We propose a system of integrating SPC tools as a component of the audit function of a PCI unit.nnnCONCLUSIONSnSPC tools have the potential to provide near real-time performance monitoring and may allow early detection and intervention in altered performance for both the group and the individual operator. A clinically-integrated system of SPC tools may thus complement and enhance effectiveness of the traditional case-based morbidity and mortality audit.

The role of quantitative feedback in coronary angiography radiation reduction

OBJECTIVEnTo evaluate the benefits of radiation education with and without feedback reporting in altering clinician radiation use behaviour in performing coronary angiography (CA).nnnDESIGNnA retrospective review of radiation use (fluoroscopy time) in coronary angiograms performed between July 1996 and December 2005 by 10 cardiologists to assess the impact of various interventions aimed at minimizing radiation risk. The impact of interventions such as education and audit/feedback was correlated against radiation use using cumulative sum and cumulative expected minus observed charts.nnnSETTINGnPrivate Hospital in Brisbane, Australia.nnnPARTICIPANTSnTen cardiologists.nnnINTERVENTIONnEducation and audit/feedback.nnnRESULTSnBaseline radiation use subject to standard guidelines was stable. Group performance charts show a modest transient improvement in radiation use associated with an education intervention alone. However, regular detailed personalized feedback comparing an individuals radiation use to group and external benchmarks was successful in achieving sustained reduction in overall radiation use. For individual participants, significant improvement was noted in 7 of 10 cardiologists.nnnCONCLUSIONnAlthough an improved theoretical understanding of effective radiation hygiene strategies might contribute to reduced radiation use, this study suggests that regular detailed quantitative feedback supporting education is an effective tool in altering radiation use in CA. Understanding triggers that stimulate change in clinician behaviour is critical to the design of systems to optimize clinical performance. Confidentially reported benchmarking systems may be a useful tool to alter clinician behaviour.

Risk Modelling in Quality Clinical Registries: Monitoring Lesion Treatment Failure Rate in Percutaneous Coronary Interventions

AIMSnThis paper describes the development of a risk adjustment (RA) model predictive of individual lesion treatment failure in percutaneous coronary interventions (PCI) for use in a quality monitoring and improvement program.nnnMETHODS AND RESULTSnProspectively collected data for 3972 consecutive revascularisation procedures (5601 lesions) performed between January 2003 and September 2011 were studied. Data on procedures to September 2009 (n=3100) were used to identify factors predictive of lesion treatment failure. Factors identified included lesion risk class (p<0.001), occlusion type (p<0.001), patient age (p=0.001), vessel system (p<0.04), vessel diameter (p<0.001), unstable angina (p=0.003) and presence of major cardiac risk factors (p=0.01). A Bayesian RA model was built using these factors with predictive performance of the model tested on the remaining procedures (area under the receiver operating curve: 0.765, Hosmer-Lemeshow p value: 0.11). Cumulative sum, exponentially weighted moving average and funnel plots were constructed using the RA model and subjectively evaluated.nnnCONCLUSIONnA RA model was developed and applied to SPC monitoring for lesion failure in a PCI database. If linked to appropriate quality improvement governance response protocols, SPC using this RA tool might improve quality control and risk management by identifying variation in performance based on a comparison of observed and expected outcomes.