Background: The randomised controlled trial (RCT) is the most appropriate study design for deriving an accurate unbiased estimate of the efficacy of a new technology relative to current best practice, and funding/regulatory bodies often require high quality RCT evidence to underpin decisions about clinical and cost-effectiveness. Where randomisation is not possible, other forms of controlled evidence may be relied upon. In contrast, evidence from case series is rarely considered to be of value in assessing efficacy since any observed improvement in patient outcomes could be attributed to factors other than the effects of the intervention. Objectives: To determine the effects of a unique ‘curative’ procedure and to discuss if, in certain circumstances, early evidence of efficacy from case series could be so convincing as to jeopardise the equipoise required to undertake an ethical randomised study. Methods: A systematic review of radiofrequency catheter ablation (RFCA) for the treatment of atrial flutter. Results: We discovered 23 case series and two small RCTs. The case series indicated that freedom from flutter was maintained at follow-up in 68% to 98% of patients ablated. Both RCTs showed RFCA to be superior to antiarrhythmic drugs, but both had important shortcomings, and there remains considerable uncertainty about how well RFCA works relative to other treatment options on several key outcomes. Conclusions:Whether a new RCT is required to establish the true clinical effects of RFCA is an area of controversy, with many cardiologists considering the dramatic cuts in rates of atrial flutter from published case series of RFCA to be sufficiently convincing evidence of efficacy. Because of the natural history of the disease, such improvements have almost entirely been attributed to the ‘curative’ effect of RFCA. We discuss different stakeholders’ (e.g. clinicians, researchers, policymakers) differing interpretations of research evidence and the implications for health technology
assessment.