Coronary microvascular dysfunction may be related to IGF-1 in acromegalic patients and can be restored by therapy.

BACKGROUND AND AIMS: Acromegaly increases the risk of cardiovascular mortality. Data on the cardiovascular risk in asymptomatic acromegaly are limited. In particular, data on coronary microvascular abnormalities are lacking. We assessed coronary flow reserve (CFR) as a marker of coronary microvascular function in asymptomatic acromegaly. METHODS: We studied 40 acromegalic patients (23 male, age 52 ±â€¯11 years) without clinical evidence of cardiovascular disease, and 40 control subjects matched for age and sex. Coronary flow velocity in the left anterior descending coronary artery was detected by transthoracic Doppler echocardiography, at rest, and during adenosine infusion. CFR was the ratio of hyperaemic to resting diastolic flow velocity. RESULTS: CFR was lower in patients than in controls (2.9 ±â€¯0.8 vs. 3.7 ±â€¯0.6, p < 0.0001) and was abnormal (≤2.5) in 13 patients (32.5%) compared with any control subjects (0%) (p < 0.0001). CFR was inversely related to insulin-like growth factor 1 (IGF-1) levels (r = -0.5, p < 0.004). In patients with CFR≤2.5, IGF-1 was higher (756 [381-898] µg/l versus 246 [186-484] µg/l, p < 0.007) whereas growth hormone (GH) levels were similar (6.3 [2.8-13.7] µg/l versus 5 [2.8-8.9] µg/l, p = 0.8). In multivariable linear regression analysis, IGF-1 was independently associated with CFR (p < 0.0001). In multiple logistic regression analysis, IGF-1 independently increased the probability of CFR≤2.5 (p = 0.009). In four patients with active disease (all with CFR<2.5), treatment with somatostatin analogues normalized CFR. However the other four patients with active disease were not responder. CONCLUSIONS: Acromegalic patients have coronary microvascular dysfunction that may be restored by therapy with somatostatin analogues. IGF-1 independently correlates with the coronary microvascular impairment, suggesting the pivotal role of this hormone in explaining the increased cardiovascular risk in acromegaly.

Coronary microvascular dysfunction due to essential thrombocythemia and policythemia vera: the missing piece in the puzzle of their increased cardiovascular risk?

Myeloproliferative neoplasms are most commonly associated with venous thrombosis. Up to 60% of patients experience a thrombotic event in their lifetimes, including stroke or myocardial infarction. It is unclear whether pathogenetic factors linking essential thrombocythemia (ET) and polycythemia vera (PV) to thrombotic complications do play a role in the risk of coronary artery disease (CAD). We aimed to assess coronary flow reserve (CFR) as a marker of coronary microvascular function in asymptomatic patients with ET and PV. Fifty-two patients with ET (M/F 13/39, age 61 ± 7 years) and 22 patients with PV (M/F 13/9, age 60.4 ± 13 years) without clinical evidence of heart disease, and 50 controls matched for age and gender were studied. None had CAD. All control subjects were asymptomatic with no history of heart disease. CFR in the left anterior descending coronary artery was detected by transthoracic Doppler echocardiography, at rest, and during adenosine infusion. In patients with ET and PV, CFR was lower than in controls (2.9 ± 0.94 and 2.2 ± 0.7 vs. 3.8 ± 0.7, P < 0.004 and P < 0.0001 respectively). The prevalence of CFR ≤ 2.5 was higher in patients with ET (20 cases, 38.5%) and PV (15 cases, 68.2%) compared with controls (4.1%) (P < 0.0001). Severe CFR (CFR < 2) impairment was found in eight patients with ET (15.4%), in nine patients with PV (40.9%), and in none of control subjects. The mutation of JAK2 gene was associated with abnormal CFR. Asymptomatic patients with ET and PV have coronary microvascular dysfunction in the absence of clinical conditions suggesting CAD.

Coronary microvasculopathy in heart transplantation: Consequences and therapeutic implications.

Despite the progress made in the prevention and treatment of rejection of the transplanted heart, cardiac allograft vasculopathy (CAV) remains the main cause of death in late survival transplanted patients. CAV consists of a progressive diffuse intimal hyperplasia and the proliferation of vascular smooth muscle cells, ending in wall thickening of epicardial vessels, intramyocardial arteries (50-20 µm), arterioles (20-10 µm), and capillaries (< 10 µm). The etiology of CAV remains unclear; both immunologic and non-immunologic mechanisms contribute to endothelial damage with a sustained inflammatory response. The immunological factors involved are Human Leukocyte Antigen compatibility between donor and recipient, alloreactive T cells and the humoral immune system. The non-immunological factors are older donor age, ischemia-reperfusion time, hyperlipidemia and CMV infections. Diagnostic techniques that are able to assess microvascular function are lacking. Intravascular ultrasound and fractional flow reserve, when performed during coronary angiography, are able to detect epicardial coronary artery disease but are not sensitive enough to assess microvascular changes. Some authors have proposed an index of microcirculatory resistance during maximal hyperemia, which is calculated by dividing pressure by flow (distal pressure multiplied by the hyperemic mean transit time). Non-invasive methods to assess coronary physiology are stress echocardiography, coronary flow reserve by transthoracic Doppler echocardiography, single photon emission computed tomography, and perfusion cardiac magnetic resonance. In this review, we intend to analyze the mechanisms, consequences and therapeutic implications of microvascular dysfunction, including an extended citation of relevant literature data.