Commentary: Transcatheter Aortic Valve Implantation in Patients With Left Ventricular Dysfunction: Worse Outcomes or Greatest Chance for Improvement?

Patients with aortic valve stenosis and depressed left ventricle (LV) function represent a particularly challenging group. Their symptoms might be a manifestation of the LV dysfunction, the aortic stenosis, or both. Commonly, the inability to generate a sufficiently high aortic valve gradient might delay or even obscure the correct diagnosis.¹ When aortic stenosis is suspected, assessment with dobutamine infusion is suggested as a way to measure contractile reserve and indicate the true severity of the aortic stenosis. This will also help indicate whether the patient will benefit from surgical aortic valve replacement (SAVR).^2,3 For example, if LV dysfunction is the cause of the problem and the aortic stenosis is only mild, these patients generally will not benefit from SAVR. Such patients generally do not increase their gradient when challenged with a dobutamine infusion. On the other hand, patients who are able to increase their aortic gradient, and thus have some contractile reserve, often do better with surgery. 

The advent of transcatheter aortic valve replacement (or transcatheter aortic valve implantation [TAVI], as it’s called here), has opened up a new avenue for many patients who previously were deemed higher risk for SAVR.⁴ Aortic stenosis patients with LV dysfunction certainly fall into this category, since one predictor of higher surgical risk is LV dysfunction. With the growth and evolution of TAVI, reports have now begun to appear on its use in patients with underlying LV dysfunction.^5,6 More reports are to be greatly encouraged. Clavel et al, for example, found better LV functional recovery with TAVI in patients with LV dysfunction compared with SAVR.⁵ Yet in the PARTNER trial (cohort A), Elmariah et al reported similar mortality and LV functional recovery between TAVI and SAVR patients. One particularly interesting finding in this PARTNER study report was that failure to improve LV ejection fraction (LVEF) by 30 days was associated with adverse 1-year outcomes after TAVI, but not after SAVR.⁶ Nevertheless, one has to remember that patients with severe LV dysfunction (LVEF <20%) were excluded from the PARTNER trial, and the inclusion criteria required a mean aortic valve gradient of 40 mm Hg or an aortic velocity of 4 m/s. These criteria may have effectively excluded patients with depressed LV function unable to generate a sufficient valve gradient, introducing a selection bias.

In this issue of the Journal, Elhmidi et al from Munich, Germany, report their experience with TAVI in patients with LV dysfunction.⁷ Of the 505 patients studied, 70 patients (14%) had severe LV dysfunction (LVEF ≤35%) and 111 patients (22%) had moderate LV dysfunction (LVEF 35%-50%), while the remainder had normal LV function. The mortality of patients with severe LV dysfunction vs those with normal function was almost double at 6 months (26.9% vs 15%, respectively). Patients in the intermediate category also had higher mortality (22.9%). Yet, in addition to predicting lower survival, severe LV dysfunction was also an independent predictor of LV functional recovery, suggesting that those patients had the most to gain from TAVI. Important limitations in these findings are that there was no examination of a “learning curve” effect, as noted by Clavel et al.⁵ Mortality might be influenced by any such learning curve associated with the procedure. Comparing patients done in the first half of the timeline with the last half might help in that respect. There was also no assessment of patients with LV dysfunction using dobutamine infusion to determine contractile reserve.

Patients with both severe aortic stenosis and severe LV dysfunction therefore present us with a curious dilemma. On the one hand, they may have significantly lower long-term survival rates, yet on the other hand their LV dysfunction may have the best opportunity for greater recovery after the TAVI procedure. Overall, in our opinion, the data presented here support the use of TAVI in patients with moderate and severe LV dysfunction. The glass appears to be half full rather than half empty. The critical question that remains unanswered is: How can we predict those patients who will not have any improvement in LV function and clinical status with TAVI? Reports like this one are encouraging and hopefully will prompt additional studies on this important question. 

References

1. Pibarot P, Dumesnil JG. Low-flow, low-gradient aortic stenosis with normal and depressed left ventricular ejection fraction. J Am Coll Cardiol. 2012;60(19):1845-1853.
2. Nishimura RA, Grantham JA, Connolly HM, Schaff HV, Higano ST, Holmes DR  Jr. Low-output, low-gradient aortic stenosis in patients with depressed left ventricular systolic function: the clinical utility of the dobutamine challenge in the catheterization laboratory. Circulation. 2002;106(7):809-813.
3. ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): developed in collaboration with the Society of Cardiovascular Anesthesiologists: endorsed by the Society for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons. Circulation. 2006;114(5):e84-e231.
4. Osnabrugge RL, Mylotte D, Head SJ, et al. Aortic stenosis in the elderly: disease prevalence and number of candidates for transcatheter aortic valve replacement: a meta-analysis and modeling study. J Am Coll Cardiol. 2013;62(11):1002-1012.
5. Clavel MA, Webb JG, Rodes-Cabau J, et al. Comparison between transcatheter and surgical prosthetic valve implantation in patients with severe aortic stenosis and reduced left ventricular ejection fraction. Circulation. 2010;122(19):1928-1936.
6. Elmariah S, Palacios IF, McAndrew T, et al. Outcomes of transcatheter and surgical aortic valve replacement in high-risk patients with aortic stenosis and left ventricular dysfunction: results from the Placement of Aortic Transcatheter Valves (PARTNER) trial (cohort A). Circ Cardiovasc Interv. 2013;6(6):604-614.
7. Elhmidi Y, Bleiziffer S, Deutsch M-A, et al. Transcatheter aortic valve implantation in patients with LV dysfunction: impact on mortality and predictors of LV function recovery. J Invasive Cardiol. 2014:26(3):132-138.