**4. Discussion and conclusions**

Postoperative mortality and valve related complications received much attention in most patients series. Recently, other cardiac complications such as heart failure, conduction defects and atrial fibrillation were also scrutinized. Univariate analysis as screening and subsequent multivariate analysis as identification of risk factors for each event could be helpful patient selection and, more importantly, improve postoperative results if these risk factors are liable for alteration.

Mortality and congestive heart failure, which was identified as the most lethal cardiac complication, were clearly patient related. One might expect a reduction in these events if patients are referred early, once aortic valve degeneration has become symptomatic. This could avoid the appearance of a major risk factor, i.e. the need for urgent valve replacement. This is the clear consequence of a protracted pressure overload on the left ventricle by the diseased aortic valve and the ultimate marker for advanced heart valve disease.

Thromboembolism and bleeding are typically considered as valve related events. The former, however, could also be related to patient factors, while the latter could also be

The 30 Day Complication Rate After Aortic Valve

this difference was not significant (97).

Dis 2006;15:43-48

condition.

**5. References** 

2720.

Replacement with a Pericardial Valve in a Mainly Geriatric Population 119

for conventional AVR, TAVI was compared to balloon valvotomy through a randomized controlled (PARTNER) trial. Mortality (30-day and one-year) from any cause and repeat hospitalization as well as occurrence of cardiac symptoms (higher NYHA functional class) were significantly reduced after TAVI. Major strokes, bleeding events and major vascular events occurred more often, however. Balloon valvotomy did not alter the course of aortic valve disease. Paravalvular leaks after TAVI were usually mild and did not worsen after one year. Postprocedural stroke was troublesome, but might be reduced by developing smaller delivering devices. These results cannot be extrapolated to patients in whom conventional AVR is an option (7). The trans-apical approach for TAVI is a feasible alternative in high risk elderly patients with symptomatic aortic valve disease and peripheral artery disease. There is no need for sternotomy or extracorporeal circulation. No post-procedural stroke was observed, probably due to the avoidance of an atheromatous aortic arch. Presence of preoperative respiratory dysfunction proved to be a risk. The procedural success rate was high. Compared to a control group of patients who underwent conventional AVR (by propensity score analysis), 30-day and one-year survival superior for trans-apical TAVI, but

To document the superiority of either of these minimal approaches, RCT on sufficiently large scale are needed. For ministernotomy and minithoracotomy, these are feasible, but still lacking. For TAVI, it is currently unethical for patients to subject patients to the still unknown long-term results of TAVI if these are deemed fit for conventional AVR. Conventional AVR still can be considered as the standard therapy for degenerative aortic valve disease, with very predictable results, even in the elderly and patients with co-morbid

[1] Somers P, Knaapen M, Kockx M, Van Cauwelaert P, Bortier H, Mistiaen W. Histological

[2] Somers P, Knaapen MWM, Mistiaen W. Histolopathology of calcific aortic valve

[3] Mistiaen W, Somers P, Knaapen MWM, Kockx MM. Autophagy as Mechanism for Cell

[4] Mistiaen W, Knaapen M. Evaluation of cell death markers in severe calcified aortic

[6] Iung B, Cacier A, Baron G, Messika-Zitoun D, Delahaye F, Tornos P, Gohlke C, Boersma

[7] Leon MB, Smith CR, Mack M, et al for the PARTNTER trial investigators. Transcatheter

[8] Hickey E, Langley SM, Allemby-Smith O, Livesey SA, Monro JL. Subcoronary allograft

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valves. Methods In Enzymology 2009, 453:365-378. [5] Carabello BA, Paulus WJ. Aortic stenosis. Lancet 2009; 373: 956–66.

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Aortic-Valve Implantation for Aortic Stenosis in Patients Who Cannot Undergo

aortic valve replacement: parametric risk-hazard outcome analysis to a minimum

related to the procedure. Both events could have a significance as risk factor for long-term recurrence.

Occurrence of early postoperative conduction defects and of atrial fibrillation could also be considered as markers of advanced valvular heart disease, since some of their risk factors might be the result of protracted pressure overload on the left ventricle. Hence, these events could be seen as patient related.

Non-cardiac complications could clearly be related to co-morbid conditions. These, however are not always liable to alterations. Hence, the peri- and postoperative care should be tailored for each patient. It has also become obvious that age over 80 is not a formal contraindication for AVR. Nevertheless, elderly usually have considerable co-morbidity. The EUROscore, which was developed for CABG patients overestimates the risk for hospital mortality considerably. Low ejection fraction, chronic pulmonary obstructive disease and peripheral artery disease have been identified as predictors, although (84). Pulmonary function after median sternotomy is reduced in a substantial way, probably by several mechanisms such as chest wall restriction, decreased movement of the diaphragm and impairment of diffusion across the alveolar membrane (85).

It seemed worthwhile, therefore, to explore some alternative techniques in valve surgery which could reduce the postoperative risk. These could be 1) minimal surgical access, 2) minimal extracorporeal circulation and 3) transcatheter aortic valve implantation.

The first alternative, minimal surgical access by ministernotomy (85-88) and anterolateral minithoracotomy (89-91) could expose the surgical field adequately. Possible indications could be obesity, chronic obstructive pulmonary disease (86) and previous chest irratiation or CABG with patent left internal mammary artery (91).

Some advantages have been described such as an economic benefit, improved cosmetic result, decrease in postoperative morbidity, length of stay, pain, blood loss and transfusion (86-90,92). Cross clamping time had increased, however (88). Two randomized trials have appeared, which compared minimal and conventional AVR. The first one, was very small and included 20 patients for every group (88). The second one excluded patients with obesity and pulmonary disease (85), in spite of previously mentioned indications (86). Pain and blood loss were less, but there was no less need for transfusion. No other benefits such as a decrease in renal or pulmonary complications or differences in postoperative pulmonary functions could be documented (85,88,93). Results in high risk patients were considered as excellent in a recent review, but randomized controlled trials comparing minimal with conventional AVR are needed (94).

The second approach involves the changes in extracorporeal circulation devices. The use of an extracorporeal circulation during AVR has the risks of hemodilution and of an inflammatory response, which could be reduced by an minimal extracorporeal circulation or MECC. This MECC is a closed system with a centrifugal pump, an oxygenator without a venous and cardiotomy reservoir. The patient functions as the venous reservoir (95). This reduces the contact of blood with artificial surfaces and with air. The risk for hemolysis and the need for blood transfusions also decreases (96). With MECC, there is less increase in Creactive protein, troponin I level, and better preservation of platelets and renal function. Stroke and cerebral injury were also less. The improved biocompatibility of MECC is of special advantage in high risk patients (age over 65, renal and pulmonary dysfunction). The use of a minimal ECC involves a learning curve, however (82).

More recently, TAVI or transcatheter aortic valve implantation, either through an artery or through the cardiac apex has been developed as third alternative. In patients deemed unfit for conventional AVR, TAVI was compared to balloon valvotomy through a randomized controlled (PARTNER) trial. Mortality (30-day and one-year) from any cause and repeat hospitalization as well as occurrence of cardiac symptoms (higher NYHA functional class) were significantly reduced after TAVI. Major strokes, bleeding events and major vascular events occurred more often, however. Balloon valvotomy did not alter the course of aortic valve disease. Paravalvular leaks after TAVI were usually mild and did not worsen after one year. Postprocedural stroke was troublesome, but might be reduced by developing smaller delivering devices. These results cannot be extrapolated to patients in whom conventional AVR is an option (7). The trans-apical approach for TAVI is a feasible alternative in high risk elderly patients with symptomatic aortic valve disease and peripheral artery disease. There is no need for sternotomy or extracorporeal circulation. No post-procedural stroke was observed, probably due to the avoidance of an atheromatous aortic arch. Presence of preoperative respiratory dysfunction proved to be a risk. The procedural success rate was high. Compared to a control group of patients who underwent conventional AVR (by propensity score analysis), 30-day and one-year survival superior for trans-apical TAVI, but this difference was not significant (97).

To document the superiority of either of these minimal approaches, RCT on sufficiently large scale are needed. For ministernotomy and minithoracotomy, these are feasible, but still lacking. For TAVI, it is currently unethical for patients to subject patients to the still unknown long-term results of TAVI if these are deemed fit for conventional AVR. Conventional AVR still can be considered as the standard therapy for degenerative aortic valve disease, with very predictable results, even in the elderly and patients with co-morbid condition.
