Original paper
Transcatheter implantation of atrial septal occluders in adult patients – evaluation of long-term outcome

Introduction

Atrial septal defect (ASD) and patent foramen ovale (PFO) are among the most frequent heart defects found in adult patients. Until the late 1970s surgical correction of the defect was a “gold standard’’ – now percutaneous closure of the defect with so-called “occluders” is used. The first procedure of occluder implantation was performed by King in 1976 [1].

Current guidelines of the European Society of Cardiology on the management of patients with congenital heart diseases published in 2010 qualify patients with ASD or PFO for percutaneous correction of the defect in the following situations: in patients with a significant left-to-right shunt (and with signs of right ventricular volume overload) and with vascular pulmonary resistance (PVR) < 5 mmHg/l/min (Wood units – WU) irrespective of symptoms (class of recommendation IB); if feasible occluder implantation should be a method of choice in patients with ostium secundum ASD (class of recommendation IC). Qualification for the procedure should be considered in all patients with ASD and symptoms of paradoxical embolism (after exclusion of other causes) irrespective of the shunt size (class of recommendation IIaC) and in patients with PVR > 5 mmHg but lower than 2/3 of the systemic vascular resistance (SVR) or when pulmonary artery pressure (PAP) is lower than 2/3 of the SVR (at baseline or after provocation with vasodilatory drugs [nitric oxide preferred] or after targeted treatment of pulmonary hypertension) and when a significant left-to-right shunt defined by pulmonary to systemic flow ratio (Qp/Qs) > 1.5 is present (class of recommendations IIbC) [2].

There are no univocal guidelines solving the clinical problem of qualification for the percutaneous closure of PFO as a secondary prophylaxis in patients after stroke. According to the American Heart Association and the American Stroke Association there are not sufficient data to recommend PFO closure in patients after the first stroke. Closure of the patent foramen ovale may be considered in patients with recurrence of cryptogenic stroke despite optimal treatment (class of recommendations IIbC) [3]. Ongoing multicentre controlled randomized trials (with a medical treatment arm) should help to establish the standard of care in patients with PFO (for example: PC-Trial – Patent foramen ovale and Cryptogenic embolism, RESPECT Clinical Trial – Randomized Evaluation of Recurrent Stroke comparing PFO Closure to Established Current Standard of Care Treatment, CLOSURE 1).

The aim of the study was to assess long-term results of percutaneous closure of ASD and PFO in adult patients including clinical endpoints, echocardiographic parameters and quality of life after the procedure.

Material and methods

The study group comprised 64 patients (45 women, 19 men, mean age 50.5 ±12.7 years) who underwent percutaneous closure of ASD or PFO between 2004 and 2010 in the 2nd Department of Cardiology of the Medical University of Łódź. Patients’ characteristics are presented in table 1. Qualification for the procedure in patients with ASD was performed according to contemporary guidelines. Indications for percutaneous closure of the atrial septal defect included: detection of ostium secundum ASD of > 5 mm diameter with a concomitant haemodynamically significant left-to-right shunt (pulmonary to systemic flow ratio Qp/Qs > 1.5) or detection of ASD with right atrial or right ventricular dilation or coexisting paradoxical embolism [4]. Patent foramen ovale closure was attempted in patients with documented cryptogenic stroke. Recommendations implemented after the procedure are presented in table 2.

The study included assessment of clinical endpoints in long-term observation and the change of echocardiographic parameters in control transthoracic (TTE) or transoesophageal (TEE) echocardiography (fig. 1).

The primary end-point was cardiovascular death or stroke/transient ischaemic attack (TIA). Secondary endpoints were the onset of heart failure symptoms, palpitations, syncope, peripheral or pulmonary embolism after the procedure and the need for cardiovascular interventions. Patients underwent telephone survey including information on the changes in health status and the presence of symptoms after the procedure.

Statistical analysis

Continuous variables were assessed for normality of distribution with the Kolmogorov-Smirnov test. Variables with confirmed normal distribution were presented as mean and standard deviation and variables without confirmed normal distribution were presented as median and interquartile range. Student’s t-test for unpaired samples was used to compare samples with normal distribution with significance level of  = 0.05 and Wilcoxon test was applied for samples without normal distribution with significance level of  = 0.05.

Results

Implantation of the occluder was successful in 64 patients (100% of the studied group): closure of the ostium secundum ASD was performed in 44 patients (mean age 52.8 ±13.3 years, 73% female) and closure of PFO was done in 20 patients (mean age 45.5 ±9.8 years, 65% female) due to either previous cryptogenic stroke or TIA (tab. 3).

Patients with atrial septal defect

In patients with ASD mean time of observation after the procedure was 331 ±345 days. Mean diameter of the implanted occluder was 25 ±7 mm (types: Amplatzer, Atriasept, Occlutech Figulla, Bio-Star, Intrasept, Helex).

Complete early closure of the shunt (up to 24 h) was visualized on echocardiography in 28 of the 44 patients with ASD (64%) and in 37 patients (84%) in the long-term observation. A primary clinical endpoint did not occur in any of the patients in long-term follow-up. One of the patients developed atrial fibrillation (AF) about a month after the procedure, which persisted throughout the next control examinations.

In one of the patients (one of the initial cases performed in our centre; large ASD of 34 mm diameter) migration of the occluder into the right ventricle was shown on a TEE examination 3 h after the procedure. The patient was referred for emergency surgical treatment which led to ASD correction with good effect.

Control echocardiographic examinations performed at a mean of 331 days after the procedure showed a significant reduction of right atrial (RA) and right ventricular (RV) dimensions (p < 0.001 and p < 0.0001 respectively) and decrease of Qp/Qs ratio (p = 0.005) (tab. 4).

Patients with patent foramen ovale

Mean time of follow-up after the procedure was 267 ±202 days. Mean diameter of the occluder was 24.6 ±4 mm (types: Amplatzer, Atriasept, Occlutech Figulla, Intrasept, Helex). In the case of PFO there were no signs of shunt observed directly after the procedure in the TEE examination. There were no clinical endpoints in long-term observation in any of the patients. Echocardiographic parameters did not show significant changes at control examinations. In one of the patients the control examination performed one month after the procedure disclosed onset of atrial fibrillation.

Quality of life assessment

The telephone survey was conducted on a group of 48 patients (including 31 patients with ostium secundum atrial septal defect and 17 patients with patent foramen ovale). Symptoms before the procedure (such as syncope, dizziness, peripheral oedema, limitation of exercise tolerance, palpitations, dyspnoea) were present in 26 of the 31 patients with ASD (84%). A marked improvement after percutaneous treatment of the defect was reported by 25 of them, which constitutes 96% of patients with ASD suffering from the described symptoms. The following symptoms were present in a small proportion of patients after the procedure: palpitations (in 13 patients with ASD – 42% and in 5 patients with PFO – 29%) and syncope in 1 patient with PFO (6%).

Discussion

Long-term results of percutaneous ASD and PFO treatment in our centre confirm the efficacy and safety of this method. The greatest benefits of ASD closure are seen in patients with defect correction performed before 25 years of age [2]. Nevertheless, the benefits of occluder implantation for the patients are significant irrespective of their age and include a limitation of: dyspnoea, exercise intolerance, development of pulmonary hypertension and finally right ventricular failure. According to current guidelines percutaneous closure is a preferred method of treatment [2].

Often there is a small residual shunt present directly after the procedure, which has been confirmed by the results from other centres [5]. Nevertheless, the true effectiveness of the procedure should be based on late complete shunt cessation, which was found in 37 out of 44 patients (84%) with ASD at 8 months follow-up. In patients with patent foramen ovale correction of the defect is an efficacious method of secondary prophylaxis of thromboembolic incidents, which is confirmed by the fact that there were no new strokes or transient ischaemic attacks in the studied group [6]. Reports from other centres show a direct procedure efficacy of 86-100% with recurrence of thromboembolic incidents in 0-4.9% of patients in the long-term control examinations [6-8]. There were no recurrent thromboembolic events in the presented group.

The described procedure is safe, which was also reported by other centres [9, 10]. However, in certain situations complications may appear. Quite early after introduction of this method it was suggested that percutaneous treatment of the defect may be complicated by arrhythmia. Hill and collaborators demonstrated the occurrence of supraventricular arrhythmia after the procedure, which justifies the long-term follow-up of patients for possible onset of arrhythmia [11]. Studies performed in one of the Polish centres showed that percutaneous closure of atrial septal defects may lead to onset of tachy- or bradyarrhythmia in around 1.5% of patients (11 of 739 patients who underwent the procedure) [12]. Also in our group the onset of atrial fibrillation was demonstrated in 2 patients (3%). Despite documented safety the procedure may lead to potentially severe complications such as occluder migration which requires surgical intervention [9]. There was one case of occluder migration in the presented group.

In our material as in previous reports it can be noted that percutaneous closure of ASD leads to reduction of heart cavity dimensions, improvement of right and left ventricular function and improvement of haemodynamic parameters. These changes are not only related to the cessation of symptoms but also have a protective effect against the onset of supraventricular arrhythmias [13].

Quality of life of the patients is a significant part of the procedure efficacy assessment. As demonstrated by the studies ASD leads to various symptoms, which was also confirmed by our study: 84% of patients reported clinical symptoms before the correction of the defect (26 of the 31 patients with ASD included in the telephone survey) [14]. As many as 96% of patients (25 of the 31 patients from the survey group) reported cessation or attenuation of symptoms after the procedure. Additionally, patients declared a marked quality of life improvement after the occluder implantation related not only to the cessation of clinical symptoms but also to a significantly lower fear of possible disease complications such as stroke or TIA.

Conclusions

The study showed that the procedure of percutaneous closure of ASD and PFO is safe, effective and well tolerated by the patients.

References

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