Coronary microvascular dysfunction correlates with the new onset of cardiac allograft vasculopathy in heart transplant patients with normal coronary angiography.

Coronary microvascular dysfunction is emerging as a strong predictor of outcome in heart transplantation (HT). We assessed the validity of microvascular dysfunction, defined by means of a reduced coronary flow reserve (CFR), as a factor associated with new onset epicardial cardiac allograft vasculopathy (CAV) or death. We studied 105 patients at 4 ± 1 years post-HT with a normal coronary angiography (CA). New onset CAV was assessed by CA. CFR was assessed in the left anterior descending (LAD) coronary artery by transthoracic Doppler echocardiography and calculated as the ratio of hyperaemic to basal blood flow velocity. A CFR ≤ 2.5 was considered abnormal. Epicardial CAV onset or death was assessed during a follow-up of 10 years. New onset CAV was diagnosed in 30 patients (28.6%) (Group A), and the CA was normal in the remaining 75 patients (71.4%) (Group B). Group A had reduced CFR compared with group B (2.4 ± 0.6 vs. 3.2 ± 0.7, p < 0.0001). A CFR ≤ 2.5 was independently associated with a higher probability of new onset CAV (p < 0.0001) and a higher probability of death, regardless of CAV onset (p < 0.01). Microvascular dysfunction is independently associated with the onset of epicardial CAV, and associated with a higher risk of death, regardless of CAV onset.

Everolimus prevents coronary microvasculopathy in heart transplant recipients with normal coronary angiograms: an anatomo-functional study.

BACKGROUND: Coronary allograft vasculopathy (CAV) involves both epicardial vessels and coronary microcirculation. Little is known about the effect of everolimus on coronary microvasculopathy in heart transplantation (HT). The aim of our study was to assess the pathological substrate of coronary flow reserve (CFR) impairment in HT patients and the effect of everolimus on microvascular remodeling and CFR. METHODS: We studied 28 HT patients with normal coronary angiograms (25 male, age at HT 54±10 years). Immunosuppressive regimen consisted of cyclosporine and everolimus (10 patients) or mycophenolate mophetil (18 patients). They were evaluated with digital microscopy for morphometric analysis of fibrosis and microvascular remodeling. Coronary flow velocity in the left anterior descending coronary artery was detected using transthoracic Doppler echocardiography at rest and during adenosine infusion. CFR was the ratio of hyperaemic diastolic flow velocity (DFV) to resting DFV. A CFR≤2.5 was considered abnormal and sign of coronary microvascular dysfunction. RESULTS: In patients with CFR≤2.5 the thickness of the tunica media of intramyocardial arterioles was greater than in patients with CFR>2.5 (39±2 vs 17±3 µm; P=.02). Microvascular remodeling was significantly higher in patients with CFR≤2.5 (72.7±2.4 vs 50.4±8.4%; P<.007). Capillary density and fibrosis were comparable between groups (157.2±42.4 vs 175.7±42.4 capillaries/mm2; P=.3; and 6.8±5 vs 8.3±4.9%; P=.4, respectively). The thickness of the tunica media of intramyocardial arterioles was lower in patients whose therapy included everolimus (15±2 vs 32±4 µm, P=.03) and CFR was higher (3.2±0.5 vs 2.8±0.9; P=.03). CONCLUSION: The pathological substrate of reduced CFR in HT patients seems to be a hypertrophic remodeling of coronary arterioles. Everolimus appears to prevent such microvascular remodeling and preserve coronary flow reserve.

Systemic inflammation is related to coronary microvascular dysfunction in obese patients without obstructive coronary disease.

BACKGROUND AND AIMS: Obesity, systemic inflammation and changes in the heart functions are associated with increased cardiovascular risk. This study aimed to investigate coronary microvascular dysfunction as an early marker of atherosclerosis in obese patients without any evidence of cardiovascular disease. METHODS AND RESULTS: 86 obese subjects (aged 44 ± 12 years, body mass index (BMI) 41 ± 8 kg m(-2)), without evidence of heart disease, and 48 lean controls were studied using transthoracic Doppler echocardiography for detecting coronary flow reserve (CFR). A value of CFR ≤ 2.5 was considered abnormal. We measured interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and adiponectin in all patients. Patients with abnormal CFR underwent coronary multislice computed tomography (MSCT) in order to exclude an epicardial stenosis. CFR in obese subjects was lower than in lean subjects (3.2 ± 0.8 vs. 3.7 ± 0.7, p = 0.02) and was abnormal in 27 (31%) obese patients and in one (2%) control (p < 0.0001). All subjects with abnormal CFR showed no coronary stenosis at MSCT. At multivariable analysis, IL-6 and TNF-α were the only determinants of CFR (p < 0.02 and p < 0.02, respectively). At multivariable logistic regression analysis, IL-6 and TNF-α were the only determinants of CFR ≤ 2.5 (p < 0.03 and p < 0.03, respectively). CONCLUSIONS: CFR is often reduced in obese subjects without clinical evidence of heart disease, suggesting a coronary microvascular impairment. This microvascular dysfunction seems to be related to a chronic inflammation mediated by adipocytokines. Our findings may explain the increased cardiovascular risk in obesity, independently of BMI.