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RecommendationPlease see sections 11.5 and 11.6 for recommendations on the use of anatomical and functional tests in the management of patients with stable angina.
Relative values of different outcomesThe review indicates that functional tests provide modest incremental prognostic information. The magnitude of the increment in prognostic value is however unclear. The GDG were interested in identifying prognostic information and whether acting on this prognostic information would be beneficial to patients. Since this guideline recommends that patients are given anti-anginal drugs and secondary prevention measures, the ability to identify patients who would benefit from revascularisation is critical. However neither this review nor the evidence reviews examining medical and revascularisation strategies (see chapter 10 and 11) provided robust evidence to identify patients who gain prognostic benefit from revascularisation.
Economic considerationsAll of the tests considered in this review are associated with some costs but there is no evidence that routine functional or anatomical testing provides additional clinical benefit. Routine functional testing was therefore considered not cost-effective.
Quality of evidenceThe study inclusion criteria varied widely and the study participants may not be representative of the wider population of people with stable angina.

The studies were generally small with relatively short follow-up times. Consequently most of the studies had relatively few outcome events and limited statistical power to reliably identify predictor variables. For validity of the results the analysis should have at least 10 patients (continuous) or 10 events (dichotomous) per variable.

The studies generally did not include all potentially important clinical predictors of risk in the univariate and multivariate analyses and it is therefore not possible to accurately quantify the incremental predictive value of any of the functional tests.

Several of the studies used composite outcomes. The use of revascularisation as a component of a composite outcome is problematic when assessing the prognostic value of a functional test because the test result may directly influence the likelihood that individual patients will undergo revascularisation.
Other considerationsThe GDG discussed whether it was appropriate to routinely perform tests that would provide prognostic information but that would not influence treatment. The GDG agreed the need to inform patients of the purpose and potential therapeutic implications of all investigations, particularly those associated with risk. The GDG agreed that functional and anatomical testing for prognostic information alone was unlikely to be justified or appropriate for the majority of patients. The GDG made recommendations for the use of these tests within a wider management strategy and these recommendations are found in section 11.5 and 11.6

The GDG were aware of a historical understanding in cardiology that functional testing in people with a confirmed diagnosis of stable angina is important in clinical assessment, including risk stratification and decisions about treatment. This strategy is recommended by other groups. 173

The GDG discussed evidence that did not fulfill the inclusion criteria for the review but is influential in the discussion within cardiology about the benefit of functional testing. One study reports evidence from a registry of 10627 patients (of whom 39.7% had angina) who underwent exercise or adenosine myocardial perfusion SPECT192. Myocardial revascularisation was carried out within six weeks of the scan in 671 patients, and 9956 patients were initially managed medically. All patients were followed for a mean of 1.9 years and multivariate modelling was used to assess the effect of the extent of inducible myocardial ischaemia on the relationship between treatment strategy (revascularisation or medical therapy) and cardiac mortality. Above a threshold of 10%– 12.5% ischaemic myocardium revascularisation was associated with lower cardiac death rate than medical therapy.

In the nuclear substudy of COURAGE (n=314) percutaneous coronary intervention produced more effective resolution of ischaemia than optimal medical treatment, and in multivariate analyses reduction of ischaemia was associated with greater event-free survival193.

The GDG considered evidence from these studies to be hypothesis-generating rather than definitive evidence on which recommendations could be based. The GDG considered this area a high priority for further research.

The GDG were aware that people with a confirmed diagnosis of stable angina may have had a functional or anatomical test during diagnostic assessment and that functional testing can be part of the assessment when deciding on revascularisation strategy.

From: 15, Functional and anatomical investigations

Cover of Stable Angina
Stable Angina: Methods, Evidence & Guidance [Internet].
NICE Clinical Guidelines, No. 126.
National Clinical Guidelines Centre (UK).
Copyright © 2011, National Clinical Guidelines Centre.

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