Right ventricle reverse remodelling following transcatheter and surgical secundum: Atrial septal defect closure in adults by cardiac magnetic resonance imaging

	Group 1 (Device closure) (n=15)	Group 2 (Surgical closure) (n=15)	P-value
Age (years)	33.73 ± 13.06	35.33 ± 15.18	0.75
Sex			0.65
Female	10 (66.7%)	10 (66.7%)
Male	5 (33.3%)	5 (33.3%)
BMI (Kg/m2)	24.78 ± 2.94	24.44 ± 4.02	0.79
Heart rate (bpm)	92 ± 10.14	93 ± 9.59	0.78

Table 1: Demographic date of studied patients.

In both groups, majority (66.7%) of patients were females and less than 40 years old.

There were insignificant differences between both groups as regard HR, BMI.

Clinical criteria among study groups

Thirteen out of fifteen (86.7%) and Twelve out of Fifteen (80%) patients underwent device and surgical closure, respectively had baseline NYHA class II and the majority of patients in both groups had NYHA class I after closure.

All of the patients did not have diabetes or systemic hypertension.

Assessment of the electrical remodelling parameters

Both groups showed significant reduction in QT dispersion after ASD closure when compared to the baseline values with P-value<0.05, (Table 2). However, there was no difference between both groups, (Table 3).

Table 2: ECG parameters before and after ASD closure in device and surgical group.

Table 3: ECG parameters comparing both groups.

Shunt fraction (QP/QS) by CMR

Shunt fraction assessed by CMR showed insignificant statistical difference between both groups, (Table 4).

Table 4: PAP and shunt fraction (QP/QS) in both groups.

Assessment of the mechanical remodelling by CMR

RV measurements: RVEDV and RVESV showed significant changes from the baseline measurements in both groups after ASD closure. Comparing between both groups showed significant difference between them with more reduction in the transcatheter arm with P-value <0.05, (Table 5). In device closure; RV-function after closure was significantly higher in comparison to surgical closure (P<0.001).

Table 5: Parameters of RV in comparison among two groups.

The RV mass decreased significantly in each group as absolute value from the baseline (P-value 0.001) but it was statistically insignificant different between the two groups (P-value 0.31). Univariate and multivariate logistic regression analyses were performed to identify the potential clinical, ECG and CMR predictors of remodeling. Using univariate logistics regression, TR regurgitant fraction, RA SV, LA SV, LA maximal area and QP/ QS are the predictors of remodeling. While multivariate logistic regression showed that previous predictors were insignificant.

Discussion

We included a total number of 30 adult patients, age, sex and BSA matched patients in a prospective study to compare short term outcome of the RV electrical and mechanical remodelling parameters after transcatheter and surgical ASD closure.

The main purpose of ASD closure is the abortion of shunt with excess right heart volume. With our cohort, ASD surgical closure leading to both electrical remodeling of the same as percutaneous closure with better results for RV mechanical remodeling in device group.

CMR has been shown to be both reliable and reproducible in terms of quantitative RV assessment [15].

In our study there was significant shortening in the QTD after ASD closure as compared to the baseline measurements in both groups. However, there was no significant difference between the two groups.

This agree with Rücklová et al. [16] found significant reduction in the QT dispersion one month after the intervention either transcatheter or surgical closure.

We did not find superiorly of any method of closure on the ventricular electrical remodelling.

Transcatheter ASD closure had led to more reverse remodelling in the indexed RVEDV and RVESV measurements when compared to the surgical arm.

This agreed with Pascotto et al. [17] who reported failure of the surgical ASD closure to completely revert the right ventricular chamber overload, they explained this by either functional changes secondary to the effects of the cardio-pulmonary bypass technique or cardiac geometric alteration resulting from opening of the pericardial sac.

Our results disagree with the study performed by Foo et al. [5] who found no difference between the surgical and device closure groups. This can be explained by the difference of modalities used for analysis of the RV volumes. In our study we used the CMR which is considered as the gold standard for RV volumetric assessment, while Foo et al. used (2D) echocardiography which rely heavily on geometrical assumption [5].

Regarding RV function our study revealed statistically significant improvement in function in device group only, this in disagree with Berger et al. [18] who showed normalization of RVEF early after ASD closure, irrespective of whether this was achieved surgically or by transcatheter closure, which is the only study reported this, the reason for divergent results regarding RV performance after ASD closure is the limited accuracy of two dimensional echocardiography in quantifying RV parameters [19].

RV mass showed statistically significant reduction from baseline parameters. Karen et al. [20] reported reduction of RV mass 6 months post device closure. Schoen et al. [2] showed that regression of RV mass was evident within 12 months but not significantly compared with baseline MRI measurements at 6 months follow up, this due to in their study The moderator band and evident trabeculations were included in the mass and excluded from the RV volume but in our study we included trabeculations and papillary muscles as part of the RV volume will achieve higher reproducibility [21]. No study reported effect of surgery in RV mass post-surgical closure.

Using univariate and multivariate logistic regression analyses, Univariate analysis was in agree with Pascotto et al. [22] who reported a striking correlation between preprocedural cardiac overload and its reduction after shunt disappearance, regardless of the volume overload extent, and partially disagree with Thilén et al. [23] who documented that Sex, age, size of the defect, QP/ QS, RV area prior to closure did not significantly influence the potential to normalize RV area 1 year post-closure.

Conclusion

ASD closure can reverse electrical and mechanical changes in the ventricular myocardium and cause a subsequent reduction in the QT dispersion. As evidenced by CMR, both transcatheter and surgical ASD closure resulted in equivalent degrees of ventricular electrical remodeling and better ventricular mechanical remodeling. ASD percutaneous closure is beneficial not only because it is less costly and invasive than open-heart surgery, but it also improves RV function.

Limitations and Recommendations

A small sample size in our study was used due to financial constraints; patients in our developing countries were unable to pay the cost of CMR, which was performed twice (pre and post closure), and it was not covered by health insurance while I was conducting the study. We require multicenter experience rather than single-center experience.

Rather than studying a single age group, we intend to study several age groups in order to assess the effect of time course on remodeling.

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