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- Interventional cardiology and endovascular procedures
- Transcatheter valve interventions
- Aortic stenosis
- Heart failure
‘Whosoever wishes to know about the world must learn about it in its particular details.’ —Heraklietos of Ephesos
Transcatheter aortic valve implantation (TAVI) is endorsed in both the European and North American guidelines as the treatment of choice for symptomatic severe aortic stenosis in patients considered unsuitable for surgical aortic valve replacement.1 2 Neither of these documents places an upper limit of risk precluding TAVI, although patients should have an expected post-TAVI survival of at least 1 year. In patients with acutely decompensated severe aortic stenosis where the longer-term prognosis is poor or unclear, balloon aortic valvuloplasty (BAV) may be considered either as a palliative procedure or as a potential bridge to definitive therapy. The terms used to define this subset of patients are necessarily vague, as they attempt to encompass a diverse population and avoid being overly prescriptive. A number of case series and registry studies have been published describing clinical outcomes in very high-risk or acutely decompensated patients undergoing BAV as a bridge to valve replacement,3 TAVI in cardiogenic shock4 5 and emergency surgical aortic valve replacement.6 While informative, these data are limited by the bias inherent to non-randomised, observational studies and lack of an appropriate comparator. Thus, the optimal strategy for the management of severe aortic stenosis in patients with cardiogenic shock remains unclear.
In an effort to address this, Bongiovanni et al have provided a worthwhile description of clinical outcomes following emergency percutaneous treatment of severe aortic stenosis with either TAVI or aortic valvuloplasty.7 The authors performed a retrospective, observational study across five German hospitals and examined clinical outcomes for 141 patients undergoing percutaneous treatment for severe, symptomatic aortic stenosis in the setting of severely decompensated heart failure or cardiogenic shock. Twenty-three patients received emergency TAVI and 118 underwent BAV with follow-up out to 30 days.
This was clearly a high-risk cohort; all patients had clinically decompensated heart failure (pulmonary oedema or cardiogenic shock) and mean logistic EuroSCOREs were in excess of 35%. This extreme risk was reflected in the correspondingly high death rate following either procedure, several times greater than that reported in randomised trials8 and even many clinical registries.4 9 While acknowledging a lack of statistical significance, the authors highlight the numerically greater mortality in the BAV group and imply this as evidence to support the use of emergency TAVI. In truth, definitive conclusions that can be drawn are limited, but there is scope for speculation based on a closer inspection of the study design and outcomes.
First, it is important to highlight the potential selection bias, both explicit and occult, reflected in important differences in the baseline characteristics of the treatment groups. Those individuals undergoing aortic valvuloplasty were older, more likely to be female and to have a history of myocardial infarction. Although similar between cohorts, the logistic EuroSCORE is recognised to demonstrate poor calibration with observed mortality and was never intended for application in this context.10 Additional unrecorded variables, such as femoral arterial dimensions, are likely to have impacted on the technical feasibility of transfemoral TAVI and prognosis, may have influenced treatment pathway decision-making.
Second, although neither treatment demonstrated clear outcome superiority, there were notable differences in procedural risks with an increase in major vascular complications and stroke following TAVI, partly offset by a reduced incidence of significant aortic regurgitation. Reassuringly, the more invasive nature of TAVI giving rise to these complications was not associated with early hazard of death as a direct consequence of the procedure.
Third, only short-term outcome data are presented. As a result, one might be tempted to conclude that emergency BAV is associated with a lower rate of major procedural complications, a fourfold reduction in the number of required TAVI procedures required and no difference in mortality at 30 days when compared with emergency TAVI. However, this reductionist conclusion ignores the potential longer-term gains of an emergency TAVI strategy, as well as the cumulative risk associated with multiple sequential procedures.
Finally, only a third of patients who survived more than 30 days following the initial BAV subsequently underwent elective TAVI. It is unclear how this subpopulation was selected and what happened to the remainder. Without this information, it is difficult to draw any meaningful conclusions around the added value of a provisional TAVI strategy.
So how might one interpret the findings of Bongiovanni et al? Randomised clinical trials have clearly demonstrated that the long-term results following elective TAVI are superior to that achieved with BAV.8 The findings of Bongiovanni et al 7 suggest that in expert hands, emergency TAVI for the treatment of severe aortic stenosis in patients with decompensated heart failure is feasible and associated with acceptable short-term clinical outcomes. Whether emergency TAVI in this setting is superior to a strategy of emergency BAV followed by provisional TAVI, and the impact on longer-term outcomes, remains to be determined. The authors suggest, in the accepted manner, that this uncertainty is best addressed in a randomised controlled trial. In truth, however, such a trial would be extremely challenging to conduct and may struggle to provide definitive answers for such a complex and heterogeneous population.
In the absence of incontrovertible evidence, how should we treat patients with severe aortic stenosis in the setting of decompensated heart failure refractory to pharmacological treatment? Central to this decision making is the multidisciplinary Heart Team through a careful and thorough assessment to evaluate whether aortic stenosis is the principal cause of decompensation, comorbid status, technical factors and prognosis. Given the existing evidence base, it is difficult to argue in favour of a default strategy of emergency TAVI in these patients. The data presented by Bongiovanni et al suggest that, where technically feasible, in carefully selected patients with minimal comorbidity and an otherwise favourable prognosis, a strategy of up-front emergency TAVI may be considered. For the majority of patients, however, BAV affords the opportunity to palliate symptoms, assess treatment response and clarify comorbid status and prognosis.
In this age of treatment algorithms and rigid guidelines, it is refreshing to highlight the value of clinical judgement gained through corporate experience. The contribution by Bongiovanni et al 7 adds to this experience while highlighting the importance of taking time to examine the details.
Contributors PDA and NC drafted the manuscript and approved the final version for publication.
Funding PDA has received support from the New Zealand Heart Foundation. NC holds an NHS Scotland Career Researcher Award.
Competing interests None declared.
Provenance and peer review Commissioned; internally peer reviewed.
Data sharing statement The authors have no data to share for this editorial.
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