Transcatheter aortic valve replacement (TAVR) has rapidly emerged as a viable alternative for the treatment of severe symptomatic valvular aortic stenosis (AS). Almost 100,000 patients of AS have benefited from this technique. Symptomatic severe AS is a killer that needs prompt surgical intervention. The PARTNER trials established the superiority of TAVR over medical management in inoperable cases, and equivalence with surgical valve replacement in high-risk patients of AS. The UK Registry of 870 patients with mean age of 82 years now provides long- term data on efficacy of TAVR from 25 centers spread out in England and Wales.
The minimal time from TAVR to census was 4.1 years and maximal follow-up was 7 years. Significant coronary artery disease was defined as >50% stenosis affecting more than 1 major epicardial coronary artery; the median Euro SCORE was 18.5; a Core Valve was deployed in 53% patients while the remainder received the SAPIEN valve. Femoral access was used in 90% of cases with Core Valve and in about half of the patients selected for SAPIEN valve. Half of the patients studied were males and aortic valve peak gradient was 81mm Hg on an average. Around 16% patients needed permanent pacing by 30 days.
Independent predictors of mortality at 3 years were renal dysfunction, atrial fibrillation, chronic obstructive pulmonary disease, and Euro SCORE >18.5. Predictors of mortality at 5 years remained the same but there was addition of left ventricle ejection fraction less than 35% and age.
Diabetes, sex, previous cardiac surgery, peripheral vascular disease, peak aortic valve gradient and NYHA functional class were not independent predictors of mortality at 3 or 5 years. Access route or device type did not significantly affect mortality. Moderate or severe aortic regurgitation, permanent pacing or vascular complications also did not predict mortality.
Periprocedural stroke proved to be an independent predictor of mortality at 3 and 5 years.
Survival after TAVR in patients with severe AS at 3 years was 61% and 45% at follow-up of 5 years. The results are reflecting refinement in techniques and device; there was 66% survival at 2 years in PARTNER A trial and only 46% survival at 3 years in the PARTNER B trial.
The TAVR UK Registry did not notice difference in mortality treated at 3 or 5 years treated with Core Valve or SAPIEN devices. The Registry concluded that long term outcomes after TAVR are favorable with 3- and 5-year survival rates of 61% and 45% respectively.
The UK Registry is a far cry from the first case reported more than a decade ago in Circulation by Alain Cribier et al in 2002. The first human implantation was performed in a 57 years old man suffering from severe calcific AS accompanied by cardiogenic shock and an ejection fraction of 14%. The patient had bilateral pleural effusion, pulmonary edema, oliguria and systolic blood pressure of 80 mm Hg. The mean valve gradient was 30 mm Hg and valve area was 0.6 cm square. The patient had severe peripheral vascular disease with failing aorto-femoral grafts to both legs. Percutaneous balloon aortic valvuloplasty with a 20 mm balloon as tried with no enduring results.
A prototype percutaneous aortic valve device was deployed successfully using antegrade transseptal approach from the right femoral vein. The percutaneous biologic heart valve (made from bovine pericardium) was crimped over a 3 cm long and 23 mm diameter balloon catheter. The device was passed across the atrial septum and with valvular calcification used as a marker positioned at the diseased aortic valve.
Transesophageal echocardiography performed immediately post procedure demonstrated optimal device function with mean gradient of 9 mm Hg and valve area of 1.6 cm square by planimetry in cross section view. There was dramatic clinical improvement in the patient’s condition in the next 48 hours but he suffered several non-cardiac complications subsequently; pulmonary embolism necessitating intravenous thrombolysis, septicemia on day 10, worsening ischemia of the right leg requiring amputation, infection at amputation and finally death 17 weeks after the aortic device implantation. There was no autopsy done.
It was hoped that with further device modification and corroborative clinical studies, catheter based treatment of severe AS would become a “versatile therapeutic alternative.” It most certainly has.