Repaired CoA patients demonstrate an increased susceptibility for cardiovascular morbidity and mortality at long-term follow-up [
9,
10,
25‐
27]. Residual aortic obstruction in CoA patients is associated with adverse ventricular–arterial coupling related to increased LV afterload [
10]. Whether a similar cascade is also present in well-repaired CoA patients is unknown. The present study quantifies myocardial deformation in CoA patients long-term after surgical or BA repair without residual stenosis. This study adds the following to our understanding of cardiovascular health in well-repaired CoA patients long-term after repair:
Global Cardiac Function
Global LV function was preserved in our cohort of well-repaired CoA patients at long-term follow-up as previously described, expressed by normal LVEF [
4,
9,
12,
26]. Our CoA cohort also demonstrated normal LV mass and LV dimensions, suggesting that no significant LV remodeling related to potentially increased LV afterload is present in well-repaired CoA patients, which is consistent with other CMR and echocardiographic reports [
9,
10,
26]. In contrast, several echocardiographic studies showed increased LV mass after CoA repair, although these studies included CoA patients treated at significantly older age or with a longer follow-up duration (> 20 years) [
4,
11,
25]. Increased LV mass is thought to be the result of increased afterload and has been related to residual aortic stenosis at the site of previous repair [
26]. Our study demonstrates that repaired CoA patients without residual stenosis not only have preserved LV systolic function by LVEF, but also normal myocardial mass.
Left Ventricular Myocardial Deformation
Myocardial deformation was preserved in our CoA patients when compared to healthy controls, in agreement with previous echocardiography and CMR-FT reports indicating preserved longitudinal and circumferential strain in CoA patients with preserved global LV systolic function and normal LV mass [
9,
11]. Jashari et al. found reduced LV global longitudinal strain and strain rate prior to surgical CoA repair, with a further decrease shortly after intervention [
28]. Interestingly, progressive normalization of strain was observed over 2 years after satisfactory repair, resulting in near-normal LV longitudinal strain values [
28]. Kowalski et al. also showed normal global LV function and LV longitudinal strain in CoA patients by 2D echocardiographic deformation 10 years after surgical repair, suggesting a full recovery of the myocardium at long-term follow-up [
11]. In contrast, a recent CMR-FT study by Shang et al. showed impaired longitudinal deformation in CoA patients treated in the neonatal period [
10]. This study included well-repaired CoA patients treated with surgery, BA, or stent placement at an early age (before 3 months of age) [
10]. In the current study, patients treated before 3 months of age were excluded, as most patients treated at this young age suffer from a more severe coarctation, requiring immediate correction. Abnormal longitudinal deformation was explained by Shang et al. by increased arterial stiffness and altered ventriculo–arterial coupling [
10]. The pulse wave velocity in the proximal aorta was increased with increased aortic stiffness, resulting in an early return of the reflected wave, imposing increased afterload and impaired LV relaxation [
10].
Surprisingly, our CoA patients demonstrated increased systolic global longitudinal strain rate when compared to our control group. Systolic strain rate has been identified as a strong indicator for LV contractility. Increased contractile performance has been described in CoA patients after repair, as CoA patients experience increased afterload which may lead to myocardial remodeling and LV hypertrophy to maintain normal LV wall stress levels [
29]. Kimball et al. suggested that repair of coarctation may relieve the increased afterload, but myocardial hypertrophy may partially persist which results in a hypercontractile myocardial state after repair. In addition, GLS demonstrated a trend towards lower GLS in controls, which may reflect the same phenomenon of a hypercontractile state in the CoA patient group.
Conflicting data on myocardial deformation after CoA repair may be explained by differences in age at the time of repair, associated severity of CoA, and duration of follow-up between studies. The myocardial response to increased pressure load is age-dependent as the myocardium has the ability to regenerate and increase vascularity in children, thereby restoring pressure-induced remodeling with preservation of coronary blood flow and reduction of development of myocardial fibrosis [
12,
30]. Delayed repair of CoA may induce a maladaptive response of the LV, resulting in adverse outcome later in life [
12]. Age at the time of repair has therefore been identified as a predictor for impaired longitudinal strain [
31]. In addition, the set point of the renin–angiotensin–aldosterone system is defined in neonatal life [
32]. Delayed CoA repair may therefore lead to more abnormal development of the renin–angiotensin–aldosterone system, which may in turn lead to hypertension and concomitant increased LV afterload [
33,
34]. This study showed a significant correlation between age at time of repair and LV mass. However, we found no influence of age at time of repair on longitudinal strain in patients with mild-to-moderate CoA treated at a mean age of 5.9 years. Preserved longitudinal strain might suggest limited effects of adverse arterial–ventricular coupling in this patient group long-term after successful CoA repair. However, as assessment of aortic vascular function was not performed in this study, we can not assess the influence of arterial stiffness.
Jashari et al. reported more impaired longitudinal strain in CoA patients with LV hypertrophy, as confirmed by other studies [
9,
27,
28,
31]. The myofiber orientation changes throughout the myocardium, with a predominantly longitudinal orientation in the endomyocardium [
10,
27]. The endomyocardial fibers are most sensitive to pressure load-induced fibrosis [
27]. Therefore, longitudinal strain is primarily affected in patients with pressure load-induced LV hypertrophy and LV myocardial dysfunction [
27]. Well-repaired CoA patients in our cohort showed normal LV mass—hence the absence of compensatory LV hypertrophy—which may explain the preserved LV deformation indices. Our findings of preserved myocardial deformation after coarctation repair in the absence of LV hypertrophy are in line with a previous report of Kutty et al. [
9], who demonstrated reduced longitudinal LV strain in CoA patients with increased LV mass and preserved longitudinal strain in patients with normal LV mass by use of CMR-FT [
9]. In contrast to the study by Kutty et al. our current study also assessed the influence of hypertension on myocardial deformation. Our results demonstrate preserved myocardial deformation even in hypertensive patients in absence of LV hypertrophy, which might suggest that LV myocardial dysfunction occurs at a later stage in the cascade of arterial–ventricular coupling.
No difference in myocardial deformation was observed between CoA patients after BA and surgery in our study. Patients after surgery had slightly lower LVEF compared to BA patients, possibly due to the older age of the surgical patients. Similar results have been described by Chui et al. who showed a minor—non-significant—difference in LVEF between both treatment groups [
35].
Hypertension
Hypertension is a well-described long-term complication of CoA [
3,
22,
36]. Hypertension is associated with an increased afterload, LV hypertrophy, and myocardial fibrosis [
27]. Despite a high prevalence of hypertension in our patient group, LV mass and LV dimensions were preserved in our CoA patients. Hypertension did not affect global LV function or myocardial deformation in our cohort, suggesting that hypertension does not significantly affect cardiac function of well-repaired CoA patients at this point in follow-up. In fact, hypertensive CoA patients seemed to have slightly increased strain compared to controls. This difference is most likely not clinically relevant, as both strain values fall within normal range [
17]. Left ventricular remodeling and hypertrophy with impaired LV deformation have been described in hypertensive patients [
37‐
41]. In contrast to our current findings, Shang et al. reported increased LV mass and decreased myocardial deformation in hypertensive CoA patients compared to healthy controls. However, in accordance to our results, LV mass and myocardial deformation did not differ significantly between normotensive and hypertensive CoA patients [
10]. Indeed, increased systolic blood pressure has been associated with concentric hypertrophy (increased LV mass combined with increased relative wall thickness) [
42]. However, development of myocardial concentric hypertrophy is a gradual progressive process, which is usually preceded by concentric remodeling in which the relative wall thickness is increased, but LV mass is preserved [
42].