Patterns of Early Coronary Artery Changes in Pediatric Heart Transplant Recipients Detected Using Optical Coherence Tomography.

BACKGROUND: Cardiac allograft vasculopathy, the leading cause of graft failure in pediatric heart transplant recipients, is characterized by diffuse and concentric coronary intimal thickening. Early treatment yields better outcomes. While coronary angiography is the standard for cardiac allograft vasculopathy screening and diagnosis, it only identifies luminal narrowing, which occurs in more severe disease. Coronary optical coherence tomography (OCT) is a high-definition intravascular imaging modality that may offer earlier diagnosis. We used OCT to investigate coronary intimal thickening in pediatric transplant recipients and examined its (1) location (ie, vessel type and location) and (2) nature (ie, characteristics of cross-sectional and longitudinal thickening). METHODS: Sites collected coronary angiography and OCT data from participants (N=258 vessel segments from 73 individuals; median age: 11.5 years [8.4-15.3]; 55% male). Images were collected from the left anterior descending, left circumflex, and right coronary arteries, and location (ie, proximal, middle, and distal) were classified using coronary angiography. RESULTS: OCT identified 32 vessel segments meeting criteria for significant thickening, 88% of which were angiographically silent. Longitudinal thickening was segmental rather than global in 88%, and cross-sectional thickening was 48% eccentric and 52% concentric. Intimal thickening prevalence and severity measures did not consistently differ between coronary artery type (P=1.000) or location (P=0.248) but increased with time since transplant and age at transplant and OCT procedure. CONCLUSIONS: In pediatric transplant recipients, we observed a surprisingly high prevalence of segmental and eccentric intimal thickening. Insights from intravascular imaging suggest these patterns of coronary vascular changes may precede overt cardiac allograft vasculopathy. Identifying early changes may offer opportunity for enhanced surveillance and earlier intervention.

Optical Coherence Tomography for the Early Detection of Coronary Vascular Changes in Children and Adolescents After Cardiac Transplantation: Findings From the International Pediatric OCT Registry.

OBJECTIVES: This study sought to describe the initial findings from the International Pediatric Optical Coherence Tomography (OCT) registry in pediatric heart transplant recipients. BACKGROUND: Cardiac allograft vasculopathy (CAV) is a common cause of late graft failure and mortality in pediatric heart transplant recipients. Early diagnosis may improve outcomes. OCT is a high-resolution intravascular imaging technique that has the potential to identify CAV earlier than angiography. METHODS: OCT and angiography of the coronary arteries were performed in pediatric heart transplant recipients at participating centers. Demographics, clinical data, medications, episodes of rejection, and angiographically confirmed CAV were collected for each case. OCT and angiography images were analyzed in a central core imaging laboratory. Intimal thickness and intima/media cross sectional area (I/M CSA) ratios were calculated for each case. Intimal thickness ≥0.25 mm was defined as abnormal and ≥0.4 mm as severe intima thickening. I/M CSA ratio of ≥1 was defined as abnormal. OCT findings were compared to angiographic findings for each case. RESULTS: Across 3 centers, 110 cases were analyzed from 76 patients. Intimal thickening was present in 26 of 110 cases. Eleven of these cases had severe intima thickening (≥0.4 mm) and notably, angiography results were normal in 8 cases. All 5 cases with a median I/M CSA ratio of ≥2 had normal angiography. The maximal intima thickness was ≥0.25 mm in 24% and ≥0.4 mm in 10% of cases. Median I/M CSA ratio was ≥1 for 80% of cases. I/M CSA ratio was significantly higher in cases with concurrent CAV (p = 0.03). Maximal intima thickness was significantly greater in cases with current or previous rejection (p = 0.01). I/M CSA ratio was significantly lower in patients treated with statins (p = 0.01). OCT findings alone prompted a change to medical management in 17% of cases. CONCLUSIONS: OCT provides important insights into coronary vascular changes not detected by angiography in pediatric transplant recipients. The use of OCT for pediatric heart transplant recipients should be further investigated, given its potential to impact the management of CAV.

Profound myocardial ischemia associated to occlusion of the right coronary artery.

A 75-year-old man with hypertension, hypercholesterolemia and history of coronary artery disease was admitted to the hospital because of sudden loss of consciousness. The patient suffered an acute myocardial infarction seven years before this admission, which was treated with percutaneous transluminal coronary angioplasty and stent implantation in the right coronary artery. The initial electrocardiogram showed a complete atrioventricular block, with narrow ventricular complexes at a rate of 40 bpm. The next electrocardiogram, obtained after the administration of atropine, showed a sinus rhythm at 84 bpm with first-degree atrioventricular block, obvious ST-segment elevation on leads II, III, aVF, V3 to V6, and electrical alternation of the ST-segment. Subsequently, he suffered three episodes of ventricular fibrillation which were successfully defibrillated. The ST-segment elevation improved after sublingual nitroglycerine and the patient underwent urgent coronary angiography, which showed a critical stenosis in the middle part of the right coronary artery with a lot of thrombus material in the site of the previous stent. The rest of the coronary arteries did not reveal significant lesions. Thrombus aspiration and balloon angioplasty were successfully performed without residual stenosis. The ST-elevation alternans is a rare phenomenon which was initially described in the setting of coronary artery spasm. It is believed to be associated to profound myocardial ischemia, particularly in relation with occlusions of the left anterior descending coronary artery, and to the occurrence of malignant ventricular arrhythmia and sudden cardiac death.