Sumario Vol.43 - Nº 3 Julio-Septiembre 2014 Imprimir sólo la columna central

Single-Center Prospective Registry
of Valvular Transcatheter Aortic Replacement

Esteban Quarchioni, Matías Esquivel, Luis Gerardo, Alberto Licheri

Servicio de Cardiología Sanatorio de Diagnóstico y Tratamiento.
(3000) Santa Fe, Argentina.
E-mail
 
Recibido 05-MAR-14 – ACEPTADO después de revisión 20-JUNIO-2014.
The authors declare not having conflicts of interest
 
Rev Fed Arg Cardiol. 2014; 43(3): 125-129
ABSTRACT

Percutaneous or transcatheter aortic valve implantation (TAVI) is an alternative to surgical aortic valve replacement in patients with symptomatic severe aortic stenosis who are not candidates for open-heart surgery. We report the prospective registry of consecutive patients undergoing TAVIwith Medtronic CoreValve self-expanding valve at a single center, “Instituto Médico de Diagnóstico y Tratamiento de Santa Fe”, Argentina.
Key words: Aortic valve stenosis.Valve prosthesis.Aortic valve replacement.

 

INTRODUCTION
Severe aortic stenosis is the most frequent valve pathology in an elderly population. It increases its prevalence through the years, being 2.5% at 75 years old, and reaching 8.1% at 85 [1]. In symptomatic patients the prognosis is poor with a conservative treatment, so cardiac surgery is the treatment of choice. By surgical valve replacement it is possible to relieve symptoms and extend survival in most cases [2]. However, these elderly patients frequently present associated co-morbidities that increase surgical risk and post-operative morbidity, so up to a third of the candidates to surgical aortic valve replacement are rejected [3]. Implantable aortic valve prostheses by percutaneous access that have recently emerged constitute a therapeutic alternative for patients with symptomatic severe aortic stenosis and high surgical risk [4].

Security and efficacy reaches a greater rate of success at 90% and a mortality at 30 days of the procedure of less than 10% in most series, in spite of a very high risk profile in patients included in these registries [5-6].

 

MATERIAL AND METHODS
Between February 2011 and December 2013 a prospective study was conducted of consecutive patients who underwent TAVI in a single center, the Sanatorio Médico de Diagnóstico y Tratamiento de Santa Fe – Argentina. Twenty four patients with severe aortic stenosis were included, all symptomatic, with a valvular area <1 cm2 and an aortic ring diameter between 21 mm and 27 mm, ascending aorta at the level of the sinotubular junction between 40 mm and 43 mm of diameter, and with a high surgical risk defined by an interdisciplinary group of clinical cardiologists, cardiovascular surgeons, and hemodynamist, using the logistic EuroSCORE >15. Supplementary studies made before the procedure were: coronary angiography, thoracic-abdominal aortogram and distal aortography, transthoracic and/or transesophageal echo, and multidetector 64-slice computed axial tomography.

Device: The device used (CoreValveReValving System) has three elements: a) porcine pericardial tricuspid aortic valve set on a self-expanding nitinol stent; the lower portion of the valve (at the level of aortic ring) exerts a great radial force, allowing the prosthesis to fix; the middle part (at the level of the coronary arterial ostia) keeps the valve geometry and coronary flow, exerting a resistance that prevents the valve from being deformed; the upper end (at the level of the ascending aorta) has less radial force, fulfilling the function of positioning the device;b) 18-French (Fr) drug-eluting stent; c) load device.

Procedure: Valvular implant was carried out, in all cases, in the hemodynamic lab. The patients were medicated before the procedure with 100 mg of aspirin and 75 mg of clopidogrel. During the implantation procedure, heparin sodium was administered adjusted to weight (80-100 U/kg). General anesthesia was administered, antibiotic prophylaxis with cefalotin, or with vancomycin in case of allergy to beta-lactam antibiotics. Vascular access was made by surgical exposition of the femoral artery in all cases, through which the valve prosthesis transporter catheter was introduced. Puncture was made contralaterally under fluoroscopy; and with angiographic controls, the catheter implantation of temporary pacemaker (6 Fr) was conducted at the tip of the right ventricle. Next, the device was placed and released in a retrograde manner, being guided with fluoroscopy and aortography. After the implantation, the gradient between the left ventricle and the aorta was measured, and the presence of residual aortic insufficiency was assessed; when this was an angiographic degree >2, post-dilatation with balloon was performed. The procedure was completed by surgical closure of the femoral artery. The patients remained admitted with continuing monitoring in the coronary unit under the responsibility of the service of cardiovascular surgery recovery, and then in intermediate care unit, where the transitory pacemaker was withdrawn. The patients that during this period presented atrioventricular block (complete or of 2nd degree), were implanted a permanent pacemaker. Aspirin was maintained indefinitely when there were no contraindications; clopidogrel was indicated for 6 months.

Follow-up: After discharge, a full clinical and echocardiographic testing was scheduled systematically, at 30 days and later, at 3 and 6 months.

Explanations
Success of the procedure: Proper and normally functioning implantation of the prosthesis (assessed by angiography and echocardiogram), in absence of mortality during the procedure.
Vascular complications: Aortic dissection, iliac or femoral artery rupture, bleeding that required surgery and/or transfusion of 3 or more units of red blood cells.
Nephrotoxicity: because of contrast medium. Increase in serum creatinine greater than 0.5 mg/dL or greater than 25% of the previous value, 3 days after the procedure and in absence of another cause that would explain the deterioration of renal function.
Duration of the procedure: time elapsed from the admittance of the patient into the hemodynamic lab until the discharge from it.
In-hospital mortality and at one month: death by any cause occurring in the hospital or during the month after the procedure.
Mortality since the first month: death by any cause occurring since the first month of the procedure.
Total mortality: the addition of both mortalities.

Statistical analysis
The data are expressed by mean±standard deviation in the case of continuous variables, and as percentage (number) in the categorical variables.

 

RESULTS
In the study, 24 patients were included (12 men and 12 women) with average age of 83 +/- 4 years. In Tables 1 and 2 the basal characteristics and history of the population are described. All the patients presented symptomatic severe aortic valve stenosis, with dyspneabeing the most frequent symptom in FC III-IV, 66.6% (16 patients), followed by angor and syncope (Figure 1). The maximum transaortic gradient was 84±18 mmHg, and the average is 51±13 mmHg (estimated by Doppler echo). The surgical risk evaluated with the logistic EuroSCORE, was 17.8% (Table 3). In all cases, the valvular access used was the right femoral artery. In 29.1% (7 patients) of the cases, valvuloplasty was made before the implant, selecting the valve structures with a greater calcium content, and in 20.8% (5 patients) post-dilatation was made to optimize the implant of the prosthesis. In 62.5% (15 cases) a number 26 valve was implanted, and in 37.5% (9 cases) a 29 valve.

Table 1. Basal characteristics of the population
n %
  Age 83
  Male 12 50
  Female 12 50
  Hypertension 24 100
  Diabetes Mellitus 4 16,6
  Angina 4 16,6
  Dyspnea 23 95,8
  Syncope 5 20,8
  Acute pulmonary edema<1 year 9 37,5
  FC III-IV NYHA 9 37,5

 

Table 2. History of the population

n

%

  Coronary angioplasty 4 16.6
  Acute myocardial infarction 4 16.6
  CABG 0 0
  Peripheral vascular disease 6 25
  COPD 6 25
  Stroke 0 0
  Heart failure 15 62.5
  Renal failure 3 12.5
  Chronic atrial fibrillation 4 16.6
  Previous pacemaker 5 20.8
  Valvuloplasty 2 8,3
  Parkinson 1 4.1
  Porcelain aorta 1 4.1

 

Figure 1. Clinical symptoms of aortic stenosis before the procedure

 

Table 3. Age and Euroscore

Patients

Euroscore

Age

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
%
24.19
15.78
18.97
15.55
14.64
1.,6
10
21
32.1
14.75
15.65
16
17
17.9
22
18
15.6
19.29
19.2
16
17
16
15.6
24.6
17.80916667
79
88
87
88
82
82
85
81
79
85
91
84
74
85
81
84
86
81
81
80
82
82
82
83
83

The procedure was successful in all cases; no patients died during it. The surgical closure of the femoral vascular access was efficient in 100% of the cases. The duration of the procedure was 37±23 minutes. The echocardiographic measures before and after the implant show that the maximum transvalvular gradient decreased notoriously from 86.4±18 mmHg (Figure 2). These echocardiographic parameters persisted with no significant modification in the control at 6 months. Pulmonary hypertension decreased from 38.3±13 to 31.2±9 mmHg, and left ventricular systolic function improved from 58%±7 to 60%±13. The associated complications with the procedure are shown in (Figure 3). The most frequent ones were the appearance of complete atrioventricular block that required the implantation of permanent pacemaker (AVB-PM) in 33% (8 patients) of the cases; it should be highlighted that five out of eight patients that showed AVB, previously had complete CRBBB behaving as a predictor pattern. The presence of anemia with the need of more than 2 transfusions was of 20.8% (5 patients), secondary to bleeding during the procedure with no major complications. 12.5% (3 cases) were recorded of renal failure; 2 of the patients required dialysis and died at the third and fourth day of admittance respectively; in the other case hemofiltration was not necessary and there was a good evolution. Heart failure was 12.5% (3 patients) secondary to moderate to severe residual aortic insufficiency; in one of the cases a waiting management was followed; this patient presented severe acute aortic insufficiency with pulmonary edema, and required hemodynamic support for 48 h, and subsequently presented a good evolution in clinical controls, with mild to moderate residual aortic insufficiency by echocardiography. The remaining case had a difficult evolution, with heart failure persisting, to finally die at the 4th month. One case of ischemic stroke (5.8%) was recorded with recovery ad integrum, with no sequelae in the control at 6 months. There were no tamponades, acute myocardial infarction, valve migration, or complications in vascular accesses.

Figure 2. Pre and post-TAVI maximum transvalvular gradients,
and controls at a month and at 6 months

 

Figure 3. Post-TAVI complications

The time of average hospitalization was 6.8 days (coronary unit 3.8 days; ICU 2.7 days). The functional class improved in 83.3% (20 patients) of the cases, going from FC III-IV to FC I-II at discharge, maintaining this FC at 30, 90 and 180 days.

Mortality during the procedure was 0% (no patient); in-hospital mortality: 8.3% (2 patients), both cases by renal failure; mortality since the first month: 12.5% (3 patients), one case by heart failure, another by bronchopneumopathy, and the third one by unrelated pathology.

 

DISCUSSION
The results of this registry show that the percutaneous aortic valve, CoreValve®, implantation in patients with severe aortic stenosis and high surgical risk, is feasible. The efficacy of this technique is high, as shown by the echocardiographic analysis made after the implant. Aortic transvalvular gradients decreased in a remarkable way, parameters that maintained at 6 months. In spite of these encouraging results, there are acute complications derived from the procedure. Next we will analyze their causes and the ways to prevent them.

The implantation rate of permanent pacemakers in our series was 33.3%, similar to that observed in the last series published for this type of prosthesis. We should highlight that 20.8% (5 patients) already had a permanent pacemaker implanted before the procedure, for reasons not related to TAVI; otherwise, our incidence of such complication would certainly have been greater. The general reason for the appearance of complete atrioventricular block is due to the low implant of the valve, the impaction of which causes inflammation of the left ventricular outflow tract at the level of the His bundle. Currently, the ways to prevent this disorder are being studied, since their incidence is higher than that observed with the Edwards Sapiens valve (5%) [8] or with the aortic valve replacement surgery (3-5%) [9].

The vascular complications related to the puncture site or with surgical exposition were remarkably lower than those in the large trials that is around 22% of the cases, and are accompanied by a high morbi-mortality. It is worth mentioning that in our series we do not have the PROSTAR® percutaneous closure system available because of its high cost and vascular access is by surgical exposition.

The frequency of post-TAVI renal failure was 12.5% (3 patients), similar to the results from large trials; it is worth mentioning that the patients previously presented mild renal function involvement. Two of the cases required hemodialysis, being the causes of the deaths occurred in our series; this acute renal impairment increases four times the mortality in the post-implant period [10].

One case was recorded (4.1%) of ischemic stroke, a similar rate to that in current publications that are around 3 to 4%; although we should clarify that in our area we do not have diffusion filters available.

Moderate to severe residual aortic failure was 12.5% (3 patients), similar to that reported in the large trials (from 5 to 15%). One of the causes of this complication is the use of a valve with smaller dimensions; to prevent this, it is suggested to use the images in a short axis in 64-slice CAT, which allows taking the axis with a greater diameter of the aortic ring to select the proper size of the prosthesis [7]. Another cause is under-expansion, frequent in valves of high calcium content, so a waiting management could be followed in certain cases due to the self-expandable feature of the stent contained in the valve, although currently it is suggested to post-dilate with larger balloons. If it is due to an inappropriate positioning, the prosthesis can be pulled using a lasso, or a second prosthesis could be placed; both procedures are quite difficult. Moderate to severe regurgitation increases the mortality at 30 days (4.7% to 19.0%), and mortality at one year (22.1% to 61.9%) [11]. In our registry, 2 patients presented a good clinico-echocardiographic evolution; the remaining case had a difficult evolution, with heart failure persisting, and the patient dying in the fourth month.

The in-hospital mortality observed in this study was 8.3% and since the first month, 12.5%, significantly lower than that expected according to the EuroSCORE algorithm.

 

CONCLUSIONS
TAVI represents one of the greatest advancements in cardiology in recent years, and it is a feasible alternative for patients with severe aortic valvulopathy that are not surgical candidates, due to perioperative risk; with results and acceptable complication rates, in spite of being a new technique with first-generation valves, and applied to patients in high risk. Even so, we should expect the results in a long term, on the potential complications and durability of the valves before applying this treatment to younger patients and/or patients with less risk.

Limitations of the study
The significant limitations in the present study are that it is a single-center registry, in which the results of the implant of a given valve, the CoreValve® aortic valve, were analyzed in a small number of patients and with a short period of follow-up, besides not having a control group.

 

REFERENCES

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  2. ACC/AHA Guidelines for the management of patients with valvular heart disease. A report of the American Heart Association Task Force on Practice Guidelines (Committee on management of patients with valvular heart disease). J Am CollCardiol2006 48: e1-e148.
  3. Braunwald E.Valvular HeartDisease. Chapter 13. In HeartDisease. A Text Book of Medicine Cardiovascular Medicine. Braunwald E, Zipes D, Libby P. W.B. Saunders Company. 6thEd. 2001. Philadelphia, Pennsylvania. USA.
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  9. Erdogan HB, Kayalar N, Ardal H, et al: Risk factors forrequirement of permanent pacemaker implantation afteraortic valve replacement. J Card Surg2006; 21 (3): 211-5.
  10. Aregger F, Wenaweser P, Hellige GJ, et al: Risk of acutekidney injury in patients with severe aortic valve stenosisundergoing transcatheter valve replacement. Nephrol Dial Transplant 2009; 24 (7): 2175-9.
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Publication: September 2014



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