Current advances in the understanding of coronary vasospasm

Downregulated caveolin-1 expression serves a potential role in coronary artery spasm by inducing nitric oxide production in vitro

The present study aimed to investigate the effects of downregulated caveolin-1 (Cav-1) expression on nitric oxide (NO) production in lipopolysaccharide (LPS)-damaged primary human umbilical vein endothelial cells (HUVECs) in a model of coronary artery spasm (CAS) microenvironment induced by acetylcholine (ACh) treatment. Small interfering RNA (siRNA)-mediated Cav-1 downregulation in HUVECs was confirmed by western blotting. The cell viability and superoxide dismutase (SOD) inhibition in HUVECs incubated with LPS (0, 10, 25, 50, 75 and 100 µg/ml) were measured by cell counting kit-8 assay and a SOD kit, respectively. Intracellular Ca2+ [(Ca2+)i] in Fluo4-acetoxymethyl ester-loaded cells was detected by fluorescence microscopy. NO levels in the cell culture supernatants were measured by the nitrate reductase method. The results indicated that transfection with Cav-1 siRNA, in particular siCav-1 (2), downregulated the Cav-1 protein expression. LPS at a dose of 75 µg/ml induced a significant decrease in HUVECs/si-NC and HUVECs/siCav-1 viability compared with the other concentrations of LPS. Compared with the effects of untreated cells, SOD inhibition in HUVECs/si-NC and HUVECs/siCav-1 was significantly decreased by LPS (75 µg/ml). In addition, ACh stimulation caused a greater increase in [Ca2+]i in HUVECs/si-NC as compared with LPS-treated HUVECs/si-NC. ACh stimulation also induced significantly higher NO levels in LPS-treated HUVECs/siCav-1 compared with LPS-treated HUVECs/si-NC cells (P<0.05). In conclusion, the downregulated Cav-1 expression served a key role in NO production in the in vitro model of CAS induced by ACh stimulation of LPS-damaged HUVECs.

Prinzmetal Angina in a Young Patient with Essential Thrombocythemia, After Anagrelide Initiation - Case Report and Literature Review

We report a case of Prinzmetal angina as inaugural manifestation of coronary disease, in a young adult male patient, recently started on anagrelide for essential thrombocythemia. Moderate proximal left anterior descendent coronary artery stenosis was documented by angiography, and interventional or surgical revascularization has been discussed. Patient’s option was for medical therapy alone. Anagrelide was temporarily withdrawn and rechallenged uneventfully after a couple of months and clinical evolution is good at four years follow-up. The mechanism by which anagrelide could induce coronary spasm and ischemia remains to be clarified.

Interleukin-6 promotor polymorphisms and coronary vasospastic angina in Han Chinese

There is an accumulating body of evidence indicating association between inflammation and the pathogenesis of coronary vasospastic angina (CVA). Interleukin-6 (IL-6) is a pleiotropic cytokine, functions as a mediator of inflammatory response and has both pro-inflammatory and anti-inflammatory properties. The aim of the present study is to investigate the association of -634C/G polymorphism of IL-6 gene with CVA in Han Chinese. A total of 27 CVA patients and 232 healthy controls were eligible for this study. The PCR-based restriction fragment length polymorphism (PCR-RFLP) technique was used to assess the genotypes frequencies. The distribution of the IL-6 -634C/G genotypes (CC, CG, and GG) was 59.48%, 37.07%, and 3.45% in the controls, and 37.04%, 48.15%, and 14.81% in CVA group, respectively (P = 0.0080). The frequency of the G allele in the CVA group was significantly higher than that in the control group (38.89% vs 21.98%, P = 0.0057). Compared with the wild type CC, the G allele carriers (CG + GG genotypes) had increased risk of CVA in both unadjusted and adjusted analyses. These findings suggest that IL-6 -634C/G polymorphism is associated with CVA and the G allele is an independent risk for CVA in Han Chinese.

Heart failure in which coronary spasms played an important role

A 69-year-old woman was admitted for further examinations and treatment of chest pain. Emergency cardiac catheterization showed no significant stenosis on coronary angiograms; however, diffuse wall hypokinesis was observed on a left ventriculogram. After treating the patient's heart failure, cardiac catheterization was performed again. A spasm provocation test showed coronary spasms of the right and left coronary arteries. A right ventricular endomyocardial biopsy revealed denaturation and fibrosis of the myocardium under the endocardium, thus suggesting the presence of myocardial ischemia. This case highlights coronary spasms as a cause of heart failure.

Evaluation of coronary microvascular function in patients with vasospastic angina

AIM: To investigate endothelium-dependent and -independent coronary microvascular functions in patients with vasospastic angina (VSA).

METHODS: Thirty-six patients with VSA (30 men and 6 women; mean age, 58 years) were enrolled in this study. VSA was defined as ≥ 90% narrowing of the epicardial coronary arteries on angiography performed during a spasm provocation test, presence of chest pain, and/or ST-segment deviation on an electrocardiogram (ECG). Patients (n = 36) with negative spasm provocation test results and those matched for age and sex were enrolled as a control group (nonVSA group). Low-dose acetylcholine (ACh; 3 μg/min) was infused into the left coronary ostium for 2 min during the spasm provocation test. Following the spasm provocation test, nitroglycerin (0.2 mg) was administered intracoronally. Coronary blood flow (was calculated from quantitative angiography and Doppler flow velocity measurements, and the coronary flow reserve was calculated as the ratio of coronary flow velocity after injection of adenosine triphosphate (20 μg) to the baseline value. Changes in the coronary artery diameter in response to ACh and nitroglycerin infusion were expressed as percentage changes from baseline measurements.

RESULTS: Body mass index was significantly lower in the VSA group than in the nonVSA group. The frequency of conventional coronary risk factors and the rate of statin use were similar between the 2 groups. The left ventricular ejection fraction as evaluated by echocardiography was similar between the 2 groups. The duration of angina was 9 ± 2 mo. The results of blood chemistry analysis were similar between the 2 groups. Low-dose ACh did not cause coronary spasms. The change in coronary artery diameter in response to ACh was lower in the VSA group (-1.4% ± 9.3%) than in the nonVSA group (3.1% ± 6.5%, P < 0.05), whereas nitroglycerin-induced coronary artery dilatation and coronary blood flow increase in response to ACh or coronary flow reserve did not differ significantly between the 2 groups.

CONCLUSION: These findings suggest that microvascular coronary function may be preserved despite endothelial dysfunction of the epicardial coronary arteries in patients with VSA.

Increased leukocyte Rho-associated coiled-coil containing protein kinase activity predicts the presence and severity of coronary vasospastic angina

OBJECTIVE

Although inhibition of Rho-associated coiled-coil containing protein kinase (ROCK) has been shown to prevent coronary vasospastic angina (CVA), direct evidence linking ROCK activity and CVA is lacking. Accordingly, we investigated whether ROCK activity is an independent marker for CVA and is altered after treatment with antispastic medications.

METHODS AND RESULTS

We prospectively studied 31 Taiwanese patients who were diagnosed with CVA and 33 control subjects. Subject demographics were recorded, and blood samples were obtained at baseline in all participants and in CVA patients after 3 months of antispastic treatment. Compared with control subjects, leukocyte ROCK activity was greater in CVA patients (136% versus 91%, P<0.001). A cutoff value for leukocyte ROCK activity of 104% predicted the presence of CVA with specificity and sensitivity rates of 88% and 84%, respectively. ROCK activity increased with the severity of CVA (P for trend<0.001). Following 3-month treatment of antispastic agents, leukocyte ROCK activity, high-sensitivity C-reactive protein, and interleukin-6 levels were reduced by 43%, 42% and 27%, respectively (P<0.05 for all).

CONCLUSIONS

Increased levels of leukocyte ROCK activity independently predicted the presence of CVA and correlated with CVA severity. Treatment with antispastic agents substantially reduced the level of leukocyte ROCK activity.

Ergonovine stress echocardiography: Recent experience and safety in our centre

AIM

To study recent experience and safety of ergonovine stress echocardiography in our centre.

METHODS

In this study we collected the clinical variables of patients referred since 2002 for ergonovine stress echocardiography, in addition to indications, the results of this test, complications, blood pressure and heart rate values during the test and the number and results of tests requested before this technique.

RESULTS

We performed 40 tests in 38 patients, 2 tests were carried out to verify therapy efficacy. The prevalence of classic cardiovascular risk factors was low and the most frequent indication was chest pain (57.5%). Coronary angiography was performed in 32 patients, and showed normal coronary arteries in 27 patients and non-significant stenosis in 5 cases. In 16 patients, coronary angiography was carried out after a positive or inconclusive ischemia test. Another 6 patients had a normal stress test (5 exercise electrocardiography tests and 1 nuclear imaging test). Of the 40 ergonovine stress echocardiography tests, 6 were positive (4 in the right coronary artery territory and 2 in the circumflex coronary artery territory), all of them by echocardiographic criteria, and by electrocardiographic criteria in only 3 (50%). The presence of non-significant coronary artery stenosis was more frequent in patients with positive ergonovine stress echocardiography (50% vs 6%, P = 0.038), and were related to ischemic territory. During the maximum stress stage, there was a higher systolic (130.26 ± 19.17 mmHg vs 136.58 ± 27.27 mmHg, 95% CI: -12.77 to 0.14 mmHg, P = 0.055) and diastolic blood pressure (77.89 ± 13.49 mmHg vs 83.95 ± 15.73 mmHg, 95% CI: -10.41 to -1.69 mmHg, P = 0.008) than at the baseline stage, and the same was registered with heart rate (73 ± 10.96 beats/min vs 79.79 ± 11.72 beats/min, 95% CI: -9.46 to -4.11 beats/min, P < 0.01). Nevertheless, there were only 2 hypertensive reactions during the last stage, which did not force a premature end to the test, without sustained tachy or bradyarrhythmias, and the technique was well tolerated in 58% of cases. A unique complication (2.5%) of this test was a prolonged vasospasm with a slight increase in necrosis biomarkers, however, this was without repercussion.

CONCLUSION

Ergonovine stress echocardiography can be performed with safety, is well tolerated in the majority of cases, and is useful for determining the ischemia mechanism in selected cases.