Author + information
- Published online October 18, 2017.
- Francesca Raimondi, MD∗ (, )
- Giovanni Donato Aquaro, MD,
- Daniele De Marchi,
- Camilla Sandrini, MD,
- Diala Khraiche, MD,
- Pierluigi Festa, MD,
- Lamia Ait Ali, MD,
- Nathalie Boddaert, MD, PhD and
- Damien Bonnet, MD, PhD
- ↵∗Pediatric Cardiology, Hôpital Necker Enfants Malades, 149, rue de Sèvres, 75015 Paris, France
Coronary artery (CA) obstruction is the most worrying post-operative complication after the arterial switch operation (ASO) for transposition of the great arteries. Although extremely rare, late mortality is predominantly a result of sudden death and myocardial infarction (1–3).
We retrospectively reviewed cardiac magnetic resonance (CMR) of 132 consecutive and asymptomatic patients after ASO, who had no coronary artery stenosis at first systematic screening (Table 1). Seventy-nine had a coronary angiogram, 33 a computed tomography scan, and 20 had both with a mean delay between CMR and screening of 9 ± 5 years. CMR was performed using a 1.5-T scanner (HdxT or MR450 GE Medical Systems, Milwaukee, Wisconsin).
The complete imaging protocol included 3-dimensional respiratory-navigated balanced steady-state free precession sequence, first-pass perfusion before and after dipyridamole injection, unenhanced cine steady-state free precession sequences before and after dipyridamole injection, and late gadolinium enhancement studies. Segmental myocardial first-pass perfusion after dipyridamole stress and at rest were evaluated qualitatively and assessed as normal or as revealing a perfusion abnormality. The semiquantitative evaluation of myocardial perfusion was performed by the analysis of myocardial perfusion first-pass perfusion images as previously described (4). A perfusion reserve index (PRI) was calculated as the ratio of dipyridamole to rest maximal signal intensity-slope. A PRI value <1.5 in 2 contiguous myocardial segments was the perfusion positivity criterion.
Position of coronary arteries was evaluated as previously described (5). Only 1 new lesion could be identified (right coronary ostium stenosis). All 132 patients had qualitative analysis of myocardial perfusion at CMR. No qualitative defect was found.
Fifty-seven patients had a semiquantitative analysis of myocardial perfusion. Of them, 7 patients (12%) had a PRI <1.5 in at least 2 contiguous myocardial segments. In 12 patients, the left CA was reimplanted in clock position between 12 and 1 o’clock. These patients with left CA in clock position 12 to 1 o’clock had more frequent perfusion abnormality than did patients with other sites of reimplantation (7 of 12 vs. 0 of 45; p = 0.0001) and significantly lower PRI in myocardial segments irrigated by left CA myocardial than did patients with other sites of reimplantation (2.0 ± 1.0 vs. 2.7 ± 1.0; p < 0.05). No late gadolinium enhancement was found. No ischemic event was noted during annual follow-up at our institution (mean 3.0 ± 1.7 years).
Long-term outcomes in adults after ASO and risk of CA disease remain to be defined. Late mortality is predominantly a result of sudden death and myocardial infarction, but the limited number of late ischemic events after the ASO raises the question of the necessity to screen patients for CA stenosis after the ASO. First, we confirmed that myocardial perfusion is normal in a majority of patients after ASO. Consequently, sequential follow-up of myocardial perfusion is probably not mandatory once imaging of coronary anatomy shows no stenosis. Hitherto, however, we identified a subgroup of patients with anteriorly reimplanted left CA with a higher probability of perfusion abnormality. This finding is consistent with our previous report on the risk factors for early stenosis of the left coronary artery (5). This anterior position between the 2 great vessels is possibly due to the evolution of the rearrangement of the CA and the great vessels during growth. Indeed, the geometric relationships late after ASO may not be truly reflective of the geometric relationships that surgeons are confronted with in the operating room. Patients with anterior position of the left ostium represent a limited proportion of ASO patients, and this may explain the low prevalence of quantitative perfusion defects in previous series. It remains hypothetical that this subgroup of ASO patients is at higher risk of late cardiovascular events.
Our data confirm that sequential follow-up of coronary perfusion is not necessary in all patients after ASO when no coronary stenosis is found. We suggest that this follow-up has to be done in patients with anteriorly reimplanted left coronary artery. Long-term follow-up of this subgroup of patients is needed to relate this particular post-operative anatomy with potential cardiovascular events.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation
- Pasquali S.K.,
- Hasselblad V.,
- Li J.S.,
- Kong D.F.,
- Sanders S.P.
- Yacoub M.H.,
- Radley-Smith R.