Ten-year data from the NOTION trial—the longest-running clinical trial to date to compare outcomes among low-risk patients randomised to undergo either transcatheter aortic valve implantation (TAVI) or surgical valve replacement (SAVR) for aortic stenosis—have shown that patients undergoing TAVI had a similar risk of all-cause mortality, stroke and myocardial infarction (MI) as those treated surgically.
These long-term data were reported by Troels Hojsgaard Jorgensen (Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark) at the European Society of Cardiology (ESC) congress (25–28 August, Amsterdam, The Netherlands), where he also told delegates that there was a higher risk of severe structural valve deterioration after SAVR, but a similar risk of bioprosthetic valve failure with the two approaches.
The performance of transcatheter technologies in the longer term is an important current area of focus as the procedure is increasingly moving toward a younger and lower risk patient population who are expected to live longer, and Jorgensen commented that there is still “much unknown” about the long-term clinical outcomes after TAVI.
“Over the past one and a half decades, numerous randomised clinical trials have been performed ensuring that TAVI is both safe and efficient across all the surgical risk strata,” Jorgensen commented in his presentation. “This means that TAVI has moved from being indicated initially in patients with prohibitive or high surgical risk to currently being indicated for patients above 75 years of age, or having a high surgical risk, and is considered equal to surgical aortic valve replacement in patients with an intermediate surgical risk.”
Initial trials looked exclusively at extreme- or high-risk patients, typically at an advanced age, meaning that there has historically been a lack of long-term follow-up data in this area. Trials in intermediate and low-risk patient groups offer the possibility to shed greater light on this issue, but to date the best available data spans eight years, with most current trials still far behind this timepoint. The NOTION trial is one of the frontrunners in addressing the question of long-term performance in a low-risk, all-comers population, and is the first to report at a 10-year milestone.
Conducted at centres in Denmark and Sweden, the trial enrolled patients between 2009–2013 who were suitable for both TAVI and surgical valve replacement. Patients were required to be 70 years or older for inclusion in the trial. Those undergoing TAVI received the first-generation, self-expanding Corevalve (Medtronic) prosthesis, and patients undergoing SAVR received any surgical bioprosthesis at the discretion of the surgeon.
The study had a composite primary endpoint of all-cause mortality, stroke or myocardial infarction after one year. In total 280 patients, with a mean age of 79 years, were randomised to receive TAVI or surgical intervention, with 139 ending up with a transcatheter valve, and 135 a surgical valve. Jorgensen commented that up to 50% of the patient population remained alive after eight years, with only three patients lost to follow-up.
Outlining the results on clinical outcomes, Jorgensen reported that in terms of all-cause mortality there was no difference between the two groups, with a rate of 64% recorded in the SAVR arm at 10 years, compared to 62.7% in the TAVI group, while the composite rate of all-cause mortality, stroke and MI stood at 65.5% for both groups.
Looking at complications individually, investigators saw comparable rates of cardiovascular death, stroke, transient ischaemic attack, and MI between the two groups, though, unsurprisingly according to Jorgensen, there were more patients in the surgical arm with new-onset atrial fibrillation (AF), and more patients in the TAVI arm needing a permanent pacemaker after the procedure.
NOTION also sought to shed light on the question of valve durability, with investigators assessing this according to both bioprosthetic valve dysfunction, comprising of structural valve deterioration, non-structural valve deterioration, and bioprosthetic valve thrombosis or endocarditis, as well as bioprosthetic valve failure, which is made up of valve-related death, aortic valve reintervention, and severe haemodynamic structural valve dysfunction.
Structural valve deterioration was considered to be present if the patient had a transprosthetic mean gradient ≥20mmHg, an increase of 10mmHg from three months, or more than mild intraprosthetic aortic regurgitation. Jorgensen reported that the NOTION investigators found the risk of structural valve deterioration was increased in patients with a surgical bioprosthesis at 37.7%, when compared to patients with a transcatheter heart valve, whose risk was around 20.2%.
The investigators also assessed valve deterioration against a modified definition closer to that of the Valve Academic Research Consortium (VARC) 3 criteria, requiring both a high gradient alongside an increase of the gradient of at least 10mmHg or the development of more than mild intra-prosthetic aortic regurgitation, which yielded structural valve deterioration rates of 21.6% for SAVR and 15.3% for TAVI respectively.
Detailing findings on the composite risk of bioprosthetic valve dysfunction, which Jorgensen described as “perhaps the most important risk factor if you look at it as a patient”, as it comprises the risk of valve related death, the need for aortic valve reintervention, or the development of severe structural valve deterioration, there was a failure rate of 15.1% in the surgical arm, compared to 10.8% in the transcatheter arm, with no significant differences between the two groups overall, or for any of the individual endpoints apart from severe structural valve deterioration.
