Questions to Address

Preview

Summary

Questions to Address 

There are three scenarios to consider. Firstly, the ethical question of what are your institutional results with AVR and TAVR? Secondly, what are your physician and hospital alignments? Thirdly, is the moral question for greater society of what should we pay for and should healthcare be ‘rationed’ for the moderate-risk and high-risk elderly?

Results 
What are your results? This question should be relatively easy to answer yet it surprises me when we are asked to review cardiovascular programmes how scanty the data can be. Nevertheless, both institutional outcomes and individual surgeon’s outcomes should be known based on the Society of Thoracic Surgeons (STS) data or collection of state data such as in New York, Pennsylvania or Massachusetts. In a broader US context, for July 2011 to June 2012,92,514 aortic valves were sold at a cost of US$472 million, and in 2010 on average a cardiac surgeon did eight AVRs and an institution 21.^1,2 To illustrate the point, at the Cleveland Clinic in the year 2011 we did 479 isolated AVRs (we do in total about 1,500 AVRs combined with other procedures), including reoperations, emergencies and endocarditis with a predicted STS mortality score of 3.48 %, but observed mortality was in fact 0.60 % and stroke 1.50 %.³ For 2012 we did 539 patients, STS predicted death was 3.96 %, actual deaths 0.40 % and stroke 1.10 %. From 2001 to December 2007 (before potential influence of TAVR) it was only after the age of 80 years that mortality increased for reoperations to 5.6 %. However, based on careful patient selection no patient operated on over the age of 90 years died during that period. For root sparing procedures, including aortic dissections, it was 1.4 % (n=418) and for minimally invasive approaches for AVR 0.5 % (n=1,572, stroke 0.8 %). For patients <70 years old and primary operations (n=720) it was 0.28 %. Thus, because our operative results are so good this would be a considerable equipoise challenge to perform a prospective randomised study for the use of TAVR in our population. Certainly, for enrolment in the PARTNER 2A trial, this raised an ethical question of equipoise until we analysed our data in December 2012. For 257 transfemoral TAVRs there were 11 conversions (five to transapical [TA], two open AVR for ruptured roots, 4.2 %), one death (0.4 %) and two strokes (0.8 %). Up to May 2013 for 150 TA patients there were five deaths (3.3 %) and one death out of 85 patients since January 2011 (1.2 %). This compares favourably to the PARTNER A results.⁴ Hence, based on the data, we had the equipoise to enrol in the PARTNER 2A trial in which moderate-risk patients were required to have a STS score of 4–8 %, although later the upper limit was removed at the Food and Drug Administration’s (FDA) request. Nevertheless, this is a trial of moderate-risk and also high-risk patients with a new device (Sapien XT) that will help inform patient selection for AVR versus TAVR. Whether the lessons learnt from the PARTNER A trial will apply to the moderate-risk patients, such as the finding that transfemoral (TF) is better for high-risk patients with significant co-morbid disease, at the cost of 4.6 % stroke or TIA versus 1.4 % for open AVR (p=0.04), and that AVR or TA is better for more complex cardiovascular cases (like reoperations [p<0.05] or with males [p<0.05]) remains to be seen.⁵

The STS score has proven to be very accurate for prediction of deaths for the mature and technological plateaued procedure of AVR, even for STS >10 % but with wider confidence limits and receiver operating characteristic (ROC) curve c-statistics of better than 0.8.⁶ However, our attempts at finding a reliable ROC score for TAVR has not been as effective (c-statistic <0.6).⁷ Why should this be? AVR has become a mature technology for which random unpredicted events are rare, such as coronary occlusion (a good surgeon should mostly prevent this) or aortic dissection, and hence patient-related factors can be used in a predictive formula with greater reliability. For TAVR, as with other new innovative and disruptive technologies there are greater risks of both unpredictable and frequent random events. These include: failure to place the valve accurately, sizing problems, conversions, valve embolization, root rupture, ventricular perforation, aortic dissection, vascular access injury, ventricular tears, pacing wire perforations, heart block, entrapped wires or catheters, severe mitral valve regurgitation, severe perivalvular leaks, etc.^4,8 In the PARTNER A trial, 9.5 % had a failure of successful TAVR insertion based on Valve Academic Research Consortium (VARC) definitions and 10.5 % had severe or moderate perivalvular leak, also a failure by VARC; thus in total, approximately 20 % had a failed procedure. Indeed, there is some evidence that if all complications related to a TAVR procedure are combined and because transapical TAVR is associated with less bleeding and less perivalvular severe leaks, the transfemoral approach has an overall greater risk of complications for all comers. Thus, based on current known outcomes, until TAVR further matures, TAVR in moderate-risk patients should be used with caution but would depend on institutional experience and AVR outcomes.