This study which is longitudinal observation study was approved by our institutional and local review board, and written informed consent was obtained from all of the patients enrolled in this study. Thirty consecutive patients were included with isolated secundum ASD, 15 patients underwent successful transcatheter ASD device closure and 15 had surgical closure. All patients were subjected to full history, proper physical examination, 12 leads ECG and CMR before the ASD closure, and 3 months later.
Patients with secundum ASD and left to right shunt, sinus rhythm with increased RV volume load (QP/QS ratio > 1.5 and/or RV dilation) were included. Patients with secundum ASD and associated coronary artery disease or other congenital heart disease were excluded. Patients with pulmonary arterial hypertension and pulmonary vascular resistance (PVR) > 5 woods units (this according to the ESC guidelines of GUCH 2010 which considered ASD closure if PVR ≥ 5 as class IIB indication for closure which was also stated in the ESC guidelines 2020 as class III in PVR > 5 despite targeted PAH treatment) and partial anomalous pulmonary venous return were also excluded.
All patients were presented in the joint cardio-surgical meeting with the cardiology and cardiothoracic surgery. Patients with evidence of elevated pulmonary artery pressure or patients for whom non-invasive assessment of the pulmonary artery pressure was impossible or inconclusive underwent an invasive haemodynamic study as well as assessment of the pulmonary artery pressure and pulmonary vascular resistance. So, not all the surgical study cohorts underwent invasive pulmonary artery pressure evaluation. All patients who underwent transcatheter closure had assessment of the pulmonary vascular resistance.
A custom-made sheet was made for all the patients, 12 leads surface ECG as well as CMR assessment were obtained preclosure and 3 months after closure of the ASD.
Electrocardiographic study
ECG machine used was electrocardiograph ECG-2250-Nihon Kohden.
A 12-leads ECG was recorded at a speed of 50 mm/s and an amplitude of 1 mV/cm before and 3 months after ASD closure for evaluation of the following electrical parameters:
P wave duration is defined as the distance between the junction of baseline with the point of the earliest and point of latest P wave activity. The longest P wave duration was noted as P wave maximum (P max) and the shortest duration as P wave minimum (P min) in any of the 12 ECG leads (Fig. 1) [6].
P wave dispersion (Pd) is defined as the difference between the maximum and the minimum P-wave duration recorded [6]. We selected P wave duration and P wave dispersion as they are strong surrogates for prediction of atrial arrythmia.
QRS duration is defined as the widest QRS complex duration in any lead as measured from the first deflection to the last deflection crossing the isoelectric line (Fig. 2) [7].
QTc interval is defined as the interval between the beginning of the QRS complex and the end of the T wave and corrected for patients’ heart rate using Bazett formula (Fig. 3) [8].
QT dispersion (QTD) is defined as the difference between the longest (QTc max) and the shortest (QTc min) QTc intervals within a 12-leads ECG [8].
Echocardiography either transthoracic (TTE) or transoesophageal (TEE)
TTE was used to asses mean pulmonary artery pressure (MPAP) from the peak PR Doppler signal using the following formula: MPAP = 4( PR peak velocity)2 + RAP [9]. TEE was used to assess ASD size and its rims, and exclude anomalous pulmonary venous drainage.
Cardiac magnetic resonance assessment
All CMR studies were performed with subjects in the supine head first position. Using a 1.5 Tesla MRI scanner (Ingenia Philips) using a surface cardiac coil and cardiac imaging software. Scanning was performed with ECG gating during end-expiratory breath-holding phase. Steady-State Precession (SSFP) ECG gated sequences were obtained retrospectively (Image matrix 256 × 150, field of view 380 mm, repetition time 52.05 ms, echo time 1.74 ms, and flip angle 70°) [10].
MRI was used to assess ASD size, rims and shunt fraction (QP\QS). For the ventricular image set, the stack of cine SSFP images were acquired in the short axis view from the level of the mitral valve to the left ventricular apex with 8 to 12 slice thickness, and measurements were indexed to the patient’s body surface area (BSA) [11]. Analysis of the RV was performed on per slice basis by manual contouring of the endocardial and epicardial borders. Volumes were calculated based on the Simpson’s method [12]. We included the trabeculations and papillary muscles as part of the RV volume [13]
RA maximum volume was measured using the biplane area method technique in 4 and 2 chamber views [14]. The maximal RA volume was traced during ventricular systole and was defined as last cine image before opening of the tricuspid valve [14]. The RA appendage was included in the RA volume while the inferior and superior vena cava were excluded [14].
ASD closure
Percutaneous transcatheter ASD closure was performed when the anatomical characteristics and rims were adequate under general anesthesia with fluoroscopic and TEE guidance. Heparin (100 IU/kg) was given in every case. To avoid over sizing, a 24- or 34-mm sizing balloon (AGA Medical Corp.) was used to measure the diameter of the defect, and the stop-flow method balloon sizing was done with stop flow echo technique and fluoroscopic measurement was used for measurement in every patient. We did two cases through LUPV deployment technique and one through RUPV deployment technique. Balloon-assisted method (BAT) was done in one patient with absent aortic rim and with the help of a contralateral venous sheath.
The procedure was done using Amplatzer septal occluder (ASO) device, its sizes were 24 ± 6.6 mm ranging from 11 to 38 mm.
Surgical closure was done for patients with defects that were not suitable for transcatheter closure (with inadequate rims) by means of patch technique.
Statistical analysis
Data was collected and analysed using SPSS (Statistical Package for Social Science, version 25, IBM, and Armonk, NY). Numerical data was expressed in the form of mean ± SD, while categorical data was expressed in the form of frequency and percentage.
Categorical data of different groups was compared by chi-square test while numerical data of both groups was compared by Mann-Whitney U test. Baseline and follow up data of the same group was compared by Wilcoxon signed-rank test. Percentage of change between baseline and follow-up data was calculated by the following equation; percentage of change = ((follow up-baseline data)/baseline data)) × 100.
Level of confidence was kept at 95% and hence, P value was considered to be significant if < 0.05.