Regarding the total cohort, our patient population is comparable to that of many other publications concerning age, comorbidities and logistic EuroScore [3, 11‐18]. However, in contrast to other studies, logistic EuroScore and most other baseline parameters did not differ significantly between transapical and transfemoral patients. We attribute this fact to our previously described treatment strategy allocating a significant proportion of higher risk patients to the transfemoral approach to avoid general anaesthesia.

Procedural safety and outcome of TAVI at our institution are not inferior to that of other documented series [3, 11‐19]. Procedural success was very high (96.7%). The 30-day mortality (as-treated analyses) of 8.9% was well in line with the one observed in other series ranging from 5.2 [3] to 12.4% [18]. However, we could not demonstrate a significant difference in 30-day mortality between transapical and transfemoral procedures (12.4 vs. 4.8%, P = 0.08). Comparing exclusively Edwards implantations in TA and TF approaches, no statistical significant difference could be observed either (12.4 vs. 5.1%, P = 0.13). In addition, we saw no significant effect of the learning curve: 30-day mortality did not differ between the first and the second half of implantations in all procedures combined (P = 0.6), in transfemoral approaches (P = 1.0) or in transapical approaches (P = 0.6).

The correlation between postprocedural worsening of renal function and morbidity as well as mortality is well documented. We observed a high incidence of stage 3 AKI (16%), and in 15% renal replacement therapy was required. Of note, the incidence of both events was significantly higher after transapical procedures (25 vs. 6% and 22 vs. 5%, P = 0.001) in spite of comparable baseline serum creatinine levels. Regarding exclusively TA patients, persons with AKI stage III had significantly lower minimum haemoglobin values after TAVI and received significantly more red blood cell transfusions than individuals with lower AKI stages. For example, in patients without AKI (n = 22) haemoglobin fell to a minimum of 9.3 ± 1.1 g/dl and 0.3 ± 0.7 RBC units were administered, whereas in stage-III AKI patients (n = 24) minimum haemoglobin was 8.2 ± 1.0 g/dl (P = 0.0004) and 3.0 ± 2.9 RBC units were given (P < 0.0001). These findings suggest that severity of AKI in transapical procedures depends on the extent of post-operative anaemia. A similar significant correlation was not present in TF patients. It can be hypothesized that the combination of peripheral vascular disease (which was significantly more frequent in TA patients) and severe anaemia might be responsible for the higher extent of renal damage after TA TAVI.

Access complications are a major drawback of TAVI procedures, with consequent cases of death in several studies. In our cohort, we experienced major vascular complications in 24% of transfemoral procedures. However, only one death occurred due to vascular damage (thoracic aortic dissection), indicating that the team was well prepared to manage these potentially life-threatening events. Other publications using VARC or comparable definitions reported major vascular complications in 16.4 [14] and 16.2% [15] of TF patients, respectively. After the performance of the first 30 cases of overall 59 transfemoral implantations of Edwards devices in our department, the introduction of the smaller Novaflex catheter as well as growing experience led to a significant decrease of major vascular complications following these procedures (from 37 to 14%, P = 0.04).

The significantly higher rate of new-onset left bundle branch block and pacemaker implantations after CoreValve procedures has been consistently documented in many previous studies and is attributed to the deeper intraventricular insertion of this device. However, the indication for postprocedural pacemaker implantations was overall relatively low in our patients (5% in the whole cohort, 17% for CoreValve) compared to other publications reporting rates between 3.8% (exclusively Edwards prosthesis implanted) [3] and 39.3% (84% CoreValve devices implanted) [18].

We reported a 12-month survival of 72% in our cohort, which compares favourably to data from other series [3, 11, 13, 15, 20] ranging between 69 [15] and 78% [13]. Recently, a 1-year survival of 76.5% was reported for a great patient cohort (n = 1506) in the SOURCE Registry [17]. Of note, we observed no difference in 1-year survival proportions between TA and TF patients (72 vs. 71%, P = 0.9).

To date, information on further hospitalizations and incidence of MACCE during follow-up in patients after TAVI is still limited. In our study, we reported a 1-year event-free survival of 53% in the whole group which compares favourably to the findings of Leon et al. (42.5% of their patients had reached the composite end point of death from any cause or repeat hospitalization at 1 year) [15]. However, event-free-survival in these elderly patients with significant comorbidities is relatively poor. In our patients, persisting congestive heart failure was the leading reason for further hospitalization (16%), and a frequent cause of death during follow-up (3%). Dysfunction of the prosthetic valve (major paravalvular leak) was present in two TF patients necessitating reinterventions, but could be excluded in the majority of cases. In these patients, cardiac decompensation was attributed either to ischaemic heart disease, severe mitral regurgitation or severe diastolic dysfunction due to persisting left ventricular hypertrophy. In summary, follow-up morbidity seems to be substantially determined by cardiac comorbidities.

We further stratified all-cause mortality as well as event-free survival by preoperative logistic EuroScore (with cut-offs basing on recommended indications for TAVI [4, 5]) creating three subgroups of patients: EuroScore >40% (n = 28), 20–40% (n = 89), and <20%. In the latter group, very advanced age (>80 years) represented the principal reason for the heart team’s preference of TAVI over conventional surgery (n = 48). To define a consistent subgroup, the remaining 15 patients with EuroScore <20% (including 4 deaths) were not included in the following analysis because of very heterogeneous comorbidities justifying their treatment with TAVI. However, their inclusion would not have changed the statistical result. Figure 2c demonstrates the survival curves of the three defined subgroups which differed significantly (P = 0.009). One-year survival proportions were 62% in patients with a preoperative logistic EuroScore of >40% (observed median survival of 409 days), 71% in patients with EuroScore 20–40%, and 80% in octogenarians with EuroScore <20%. Regarding event-free survival as an indicator for morbidity, we obtained similar even though not statistically significant results (P = 0.1). Patients with a logistic EuroScore >40% had a 1-year event-free survival of 46%, in contrast to 52% in the second and 62% in the third group (Fig. 3c). Observed median event-free survival was 315, 442 and 710 days in the previously defined subgroups.

In conclusion, the stratification by preoperative logistic EuroScore (which is commonly used as a tool to predict 30-day mortality) allowed a convincing 1-year survival prognosis in our cohort, whereas the stratification by approach did not. Our results are suggesting that mortality and event-free survival do not primarily depend on the type of approach, but rather on the incidence of comorbidities.

In Europe, the logistic EuroScore has been widely accepted by cardiologists and cardiac surgeons as a “gold standard” [21] to aquire a general idea of peri-operative risk. In recent years it has become evident that it overestimates in-hospital mortality and that its discriminatory ability in patients undergoing aortic valve surgery is worse than in patients with isolated coronary surgery [22, 23]. Therefore, Dewey et al. [24] suggested the Society of Thoracic Surgeons (STS) Score as the most reliable single risk scoring model for both peri-operative mortality and long-term survival after isolated AVR in extremely high-risk patients. However, the STS score is much more sophisticated than the logistic EuroScore complicating its routine use in daily clinical practice. Furthermore, Leontyev et al. [25] found that stratification of octogenarians undergoing surgical AVR by logistic EuroScore revealed no significant differences in peri-operative outcomes, but proved good at differentiating survival during medium-term follow-up. The utility of both surgical prediction scores in the context of TAVI is frequently questioned. However, in our opinion the strength of scoring systems is to provide some kind of risk stratification for different patient cohorts (regardless of the calculated absolute value), whereas they are unsuitable for the prediction of an individual patient’s risk and cannot replace clinical judgement as the crucial factor of medical decision-making.

But does the performance of TAVI procedures in otherwise relatively healthy octogenarians fulfil the condition of “off-label-use”? Other TAVI series included up to 60% of patients with a logistic EuroScore <20% [18], and our own cohort compares favourably to the Source Registry [16] which consists to one-third of such patients. According to current apprehensions, the rapid spread of the TAVI technique carries the danger of withdrawing good surgical candidates from conventional aortic valve replacement. However, in our opinion this reproach would not be appropriate concerning our cohort of octogenarians characterized by a mean age of 84 ± 3 years and a mean logistic EuroScore of 14 ± 3%. As we learned from the study of Iung et al. [2], surgery is denied in at least one-third of elderly patients with symptomatic AS, and “advanced age” represents the main reason for denial of surgery. Opponents of TAVI could argue that conventional AVR is feasible in octogenarians. Previously reported in-hospital mortality rates [26‐28] ranged between 4.5 [28] and 9% [27] in selected octogenarians (logistic EuroScore not reported). Lately, the results of the PARTNER trial [3] demonstrated a mortality rate of 6.5% after surgical AVR in patients randomized for either TAVI or surgery. However, in our own specific patient cohort, in-hospital mortality was 2% with just one case of death. In addition, in this elderly population not only mortality but also morbidity after surgery is an important consideration. Ben-Dor et al. [29] reported a significant reduction of quality of life in one-fifth of elderly patients after surgical AVR, and some even lost their independence. Furthermore, prolonged hospital stays (>14 days) following this intervention were reported in up to 50% of elderly patients [26]. Finally, concerns of device durability do not have a high priority in octogenarians, and Gurvitch et al. [11] already demonstrated the absence of relevant device deterioration in a period up to 3 years.

According to our data, octogenarians with logistic EuroScore <20% seem to be acceptable candidates for TAVI procedures with good mid-term survival and reasonably low morbidity. In contrast, patients with logistic EuroScore >40% do poorly and survive on average little more than 1 year, suggesting that indication for TAVI and risk-to-benefit ratio should be validated carefully in each single case.