A method for early evaluation of a recently introduced technology by deriving a comparative group from existing clinical data: a case study in external support of the Marfan aortic root

Abstract

ObjectiveDuring the early phase of evaluation of a new intervention, data exist for present practice. The authors propose a method of constructing a fair comparator group using these data. In this case study, the authors use the example of external aortic root support, a novel alternative to aortic root replacement.DesignA matched comparison group, of similar age, aortic size and aortic valve function to those having the novel intervention, was constructed, by minimization, from among patients having conventional aortic root replacement in other hospitals during the same time frame.SettingThree cardiac surgical units in England.PatientsThe first 20 patients, aged 16–58 years with aortic root diameters of 40–54 mm, having external support surgery were compared with 20 patients, aged 18–63 years and aortic root diameters of 38–58 mm, who had conventional aortic root replacement, between May 2004 and December 2009.InterventionsA pliant external mesh sleeve, customised by computer-aided design, encloses the whole of the ascending aorta. The comparator group had conventional aortic root replacement, 16 valve-sparing and four with composite valved grafts.Main outcome measuresDuration of cardiopulmonary bypass (CPB), myocardial ischaemic time, blood loss and transfusion of blood, platelets and clotting factors.ResultsComparing total root replacement and customised aortic root support surgery: CPB (median (range)) was 134 (52–316) versus 0 (0–20) min; myocardial ischaemia 114 (41–250) versus 0 (0–0) min; 4 h blood loss was 218 (85–735) versus 50 (25–400) ml; and 9/18 had blood transfusion, 9/18 platelets and 12/18 fresh frozen plasma after root replacement versus 1/20, 0/20 and 0/20, respectively, for the novel surgery.ConclusionsAvoidance or large reductions in CPB, myocardial ischaemia and blood product usage were achieved with the novel surgery. These data are of use in decision analysis and health economic evaluation and are available early in evaluation before randomised trial data are available.

Personalised external aortic root support (PEARS) in Marfan syndrome: analysis of 1–9 year outcomes by intention-to-treat in a cohort of the first 30 consecutive patients to receive a novel tissue and valve-conserving procedure, compared with the published results of aortic root replacement

“…Analysis of periprocedural variables, compared with similar patients having root replacement surgery, confirmed that the anticipated advantages were achieved, cardiopulmonary bypass is not necessary, cardiac and circulatory arrest are completely avoided, and that blood product usage, operative time and hospital stay are commensurately reduced. 6 …”

“… 2 The computer aided design (CAD), manufacturing method and surgical technique have all remained consistent without the iterative development which has characterised the evolution of both TRR and VSRR. 3 After proof of principle 4 and prospective evaluation in the first 20 patients, 5 6 the technique has undergone Health Technology Appraisal by the British National Institute for Health and Care Excellence (NICE). 7 …”

Personalized external aortic root support: a review of the current status

“…5). There being no randomized patients, this analysis of perioperative burden of care required an innovative study design including statistical minimization to achieve the best possible comparative analysis [20]. In this analysis of the first 20 PEARS patients, compared with matched patients having root replacement, operation time was half, blood loss a quarter and transfusion and cardiopulmonary bypass were largely avoided.…”

Personalised External Aortic Root Support (PEARS) Compared with Alternatives for People with Life-Threatening Genetically Determined Aneurysms of the Aortic Root

“…There have been no aortic or valve related events ( Table 2 ). The PEARS operation is non-ablative, burns no bridges, and is a lesser biological insult than root replacement [ 38 ]. In two patients it has enabled a pregnancy [ 39 ].…”