Prinzmetal angina

Vasospastic angina (Prinzmetal s variant), unstable (crescendo or preinfarction) angina, chronic stable (effort-associated) angina PO Initially, 80-120 mg 3 times a day For elderly patients and those with hepatic dysfunction, 40 mg 3 times a day. Titrate to optimal dose. Maintenance 240-480 mg/day in 3-4 divided doses. 

Classic angina (angina of effort or exercise) is due to coronary atherosclerotic occlusion vasospastic or variant angina (Prinzmetal) is due to a reversible decrease in coronary blood low unstable angina (crescendo) presents as an acute coronary syndrome with platelet aggregation. 

Although anecdotal evidence suggested that prazosin might be useful in the treatment of patients with variant angina (Prinzmetal s angina) due to coronary vasospasm, several small controlled trials have failed to demonstrate a clear benefit. Some studies have indicated that prazosin can decrease the incidence of digital vasospasm in patients with Raynaud s disease however, its relative efficacy as compared with other vasodilators (e.g., Ca -channel blockers) is not known. Prazosin may have some benefit in patients with other vasospastic disorders. Prazosin decreases ventricular arrhythmias induced by coronary artery ligation or reperfusion in laboratory animals the therapeutic potential for this use in humans is not known. Prazosin also may be useful for the treatment of patients with mitral or aortic valvular insufficiency, presumably because of reduction of afterload. 

Vasospastic or variant angina (Prinzmetal) is due to a reversible decrease in coronary blood flow... 

Verapamil. Verapamil hydrochloride is a pbenyl alkyl amine and is considered the prototype of the Class I calcium channel blockers. Verapamil is also a potent inhibitor of coronary artery spasm and is useful in Prinzmetal s angina and in unstable angina at rest. Verapamil produces negative chronotropic and inotropic effects. These two actions reduce myocardial oxygen consumption and probably account for the effectiveness of verapamil in chronic stable effort angina (98,99). Moreover, verapamil is an effective antihypertensive agent. 

DHPs are potent arterial vasodilators. They act on resistance vessels and therefore reduce peripheral vascular resistance, lower arterial blood pressure, and antagonize vasospasms in coronary or peripheral arteries. By reducing afterload, DHPs also reduce cardiac oxygen demand. Together with their vascular spasmolytic effect, this explains most of the beneficial actions of DHPs in angina pectoris. Most DHPs are only licensed for the therapy of hypertension, some of them also for the treatment of angina pectoris and vasospastic (Prinzmetal) angina. 

The answer is a. (Hardman, pp 762-764.) Experimentally, nitrates dilate coronary vessels. This occurs in normal subjects, resulting in an overall increase in coronary blood flow. In arteriosclerotic coronaries, the ability to dilate is lost, and the ischemic area may actually have less blood flow under the influence of nitrates. Improvement in the ischemic conditions is the result of decreased myocardial oxygen demand because of a reduction of preload and afterload. Nitrates dilate both arteries and veins and thereby reduce the work of the heart. Should systemic blood pressure fall, a reflex tachycardia will occur. In pure coronary spasm, such as Prinzmetal s angina, the effect of increased coronary blood flow is relevant, while in severe left ventricular hypertrophy with minimal obstruction, the effect on preload and afterload becomes important. 

Patients with variant (Prinzmetal s) angina or cocaine-induced ACS may benefit from calcium channel blockers as initial therapy because they can reverse coronary vasospasm. /J-Blockers generally should be avoided in these situations because they may worsen vasospasm through an unopposed /T-blocking effect on smooth muscle. 

Patients with variant or Prinzmetal angina secondary to coronary spasm are more likely to experience pain at rest and in the early morning hours. Pain is not usually brought on by exertion or emotional stress nor is it relieved by rest the electrocardiogram (ECG) pattern is that of current injury with ST-segment elevation rather than depression. 

Good candidates for calcium channel antagonists include patients with contraindications or intolerance to /3-blockers, coexisting conduction system disease (excluding the use of verapamil and possibly diltiazem), Prinzmetal angina, peripheral vascular disease, severe ventricular dysfunction, and concurrent hypertension. Amlodipine is probably the agent of choice in severe ventricular dysfunction, and the other dihydropyridines should be used with caution if the EF is less than 40%. 

Do not give dihydroergotamine to patients with ischemic heart disease (angina pectoris, history of Ml, documented silent ischemia) or to patients who have clinical symptoms or findings consistent with coronary artery vasospasm, including Prinzmetal variant angina. 

Verapamil (Isoptin, Covera), in addition to its use as an antiarrhythmic agent, has been employed extensively in the management of variant (Prinzmetal s) angina and effort-induced angina pectoris (see Chapters 17 and 19). It selectively inhibits the voltage-gated calcium channel that is vital for action potential genesis in slow-response myocytes, such as those found in the sinoatrial and A-V nodes. 

All agents are also effective in the control of variant (Prinzmetal s) angina, in which spasm of the coronary arteries is the main factor. Their usefulness in the more complex unstable (preinfarction) angina is less definite, depending on the hemodynamic status and the susceptibility of the patient to infarction. 

Contraindications Basilar or hemiplegic migraine, coronary artery disease, ischemic heart disease (including angina pectoris, history of Ml, silent ischemia, and Prinzmetal s angina), uncontrolled hypertension, use within 24 hours of ergotamine-contain-ing preparations or another serotonin receptor agonist, use within 14 days of MAOls... 

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