Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002962 (angina)
 21,142 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A significant proportion of patients with cardiac syndrome X have impaired coronary vasodilator capacity, which is thought to be caused by an increased sympathetic drive. The alpha1-adrenoceptor blocker, doxazosin, increases the coronary vasodilator reserve in patients with syndrome X. To study whether the augmentation is associated with clinical improvement in patients, we conducted a double-blind, placebo controlled, crossover study with doxazosin 1 to 4 mg once daily for 10 weeks in 16 patients with syndrome X (14 women and 2 men; mean +/- SD age 56+/-5 years). Time to angina, exercise duration, time to 0.1 mV ST-segment depression, and maximal ST-segment depression during bicycle exercise testing were compared after treatment with doxazosin 2 mg or placebo for 5 weeks and again after treatment with doxazosin 4 mg or placebo for 10 weeks. Insulin sensitivity was assessed by the minimal model after 10 weeks of doxazosin or placebo treatment. Twelve patients completed the protocol. Doxazosin 4 mg/day decreased systolic blood pressure at rest (109+/-16 vs 125+/-18 mm Hg, p <0.05) and increased basal heart rate (85+/-9 vs 76+/-11 beats/min, p <0.05), whereas hemodynamics were unaffected during exercise. Time to angina, exercise duration, time to 0.1 mV ST-segment depression, and maximal ST-segment depression were similar during treatment with doxazosin and placebo irrespective of the doxazosin dose. Insulin sensitivity was not different with doxazosin and placebo. In conclusion, alpha1 blockade does not significantly improve exercise duration, angina pectoris, and ST-segment depression despite a favorable vasodilator effect in patients with syndrome X. The absent clinical efficacy of doxazosin may challenge the use of the coronary vasodilator capacity as an appropriate method to subclassify patients with syndrome X.
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PMID:Effects of doxazosin on exercise-induced angina pectoris, ST-segment depression, and insulin sensitivity in patients with syndrome X. 985 18

We sought to test the response of the coronary microcirculation to alpha-adrenoceptor blockade in patients with syndrome X (angina, ischemia-like stress electrocardiogram, and a normal coronary arteriogram). The response of the microcirculation was assessed by quantification of coronary vasodilator reserve (the ratio of hyperemic to resting myocardial blood flow). We investigated 28 patients with syndrome X [18 women, age 54.4 (7.6) years]. Myocardial blood flow was measured at rest and after dipyridamole by using positron emission tomography with H(2)15O. The measurements were made before and after treatment for 10 days with doxazosin (1 mg o.d. for 3 days, followed by 2 mg o.d. for 7 days) or a matched placebo, similarly administered. Patients were randomized to alpha1-blockade or to placebo in double-blind fashion. No significant differences were demonstrable between syndrome X patients treated with doxazosin and those receiving placebo, with respect to resting myocardial blood flow, myocardial blood flow after dipyridamole, or coronary vasodilator reserve (the ratio of the latter two). In addition, no relations were demonstrable among myocardial blood flow, coronary vasodilator reserve, development of chest pain after dipyridamole, or development of ischemia-like ECG changes. Doxazosin had no effect on the perception of chest pain after dipyridamole. No differences were found between the effects of alpha1-blockade with doxazosin or those of placebo with respect to myocardial blood flow in syndrome X. The values obtained for myocardial blood flow and coronary vasodilator reserve for the patients were within the normal range. The data do not support the case for alpha1-mediated vasoconstriction having an etiologic role in the chest pain of syndrome X.
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PMID:Effect of alpha1-adrenoceptor blockade on coronary vasodilator reserve in cardiac syndrome X. 1051 Nov 31