The introduction of transcatheter aortic valve implantation (TAVI) as a treatment for severe aortic stenosis has generated a great deal of interest amongst both cardiologists and cardiac surgeons worldwide. In the UK the number of TAVI procedures has grown steadily each year, rising from 66 in 2007 to 538 in 2009. UK registry data demonstrates an overall survival of 93.1% at one month and 78.9% at one year. Data from this registry suggests that indicators of reduced survival to be poor LV function, non-femoral access, post-procedure aortic regurgitation and logistic Euroscore of >40 ¹

As a procedure currently used to treat patients with prohibitive operative risk it is not surprising to find that the one year mortality in the UK database was of the order of 20%. The PARTNER trial reports a one year mortality similar to this (24.2% v 26.8% in transcatheter versus surgical replacement². This has prompted great interest in the literature in attempt to identify factors associated with increased procedural and long-term risk in this high risk cohort.

One recent publication, from the Thoraxcenter, (a large, high-volume TAVI centre) reports on the effect of baseline anaemia on the outcome after Corevalve TAVI³. One hundred and eighteen consecutive patients were studied from registry data collected in a prospective manner, and the analyses are post-hoc. Data is reported at one month and one year post procedure. Anaemia was defined as per WHO criteria as <13 g/dl in males, and <12g/dl in females. A large proportion of patients were noted to be anaemic at baseline (49%).

The post-procedure antiplatelet regimen included aspirin and clopidogrel for 3-6 months, and for those with an indication for coumarins, triple therapy for one month, after which aspirin was discontinued.

Baseline data:

 

The groups were well matched, with no significant differences in baseline characteristics with the exception of the haemoglobin level.

The procedural data was also presented as changes occurring within 24 hours of the procedure:

 

Interestingly, even though the patients with baseline anaemia had a lesser drop in haemoglobin level, they received more blood transfusions than their counterparts who were not anaemic at baseline.

The clinical outcomes of the patients demonstrate that there were no differences in overt bleeding between the groups, but that there was a significant difference in the one year mortality rate:

 

Data for seventy- four patients was available at one year.

Baseline anaemia was noted, as was acute kidney injury, to be an independent predictor of late mortality in patients undergoing TAVI.

 

TAVI candidates are by definition high risk, and this is reflected in the high proportion of anaemic patients in this cohort. The patients presented in this paper are reported to have been fully worked up, and the majority had multi-factorial anaemia.

The causes of death were also presented, and a non-cardiac cause of death after 30 days was higher in the anaemic group. Kaplan- Meier curve demonstrates that the mortality curve for anaemic v non- anaemic separates from around 6 months, and appears to continue to diverge as time progresses.

The authors conclude that baseline anaemia is an independent predictor of mortality at one year post TAVI.

They encourage particular emphasis on care and prevention of blood loss and access site complications during TAVI.

The long term outcomes of large national and international registries are awaited with great interest.

 

Reference List

 

  (1)   Ludman PF. The United Kingdom transcatheter aortic valve registry - outcomes to December 2009 and update. Heart 2011;97(Suppl 1):A91.

  (2)   Smith CR, Leon MB, Mack MJ et al. Transcatheter versus Surgical Aortic-Valve Replacement in High-Risk Patients. New England Journal of Medicine 2011;364(23):2187-2198.

  (3)   Van Mieghem NM, Nuis R-J, Tzikas A et al. Prevalence and prognostic implications of baseline anaemia in patients undergoing transcatheter aortic valve implantation. Eurointervention 7, 184-191. 2011.