Coronary artery spasm during exercise: treatment with verapamil

Coronary artery disease detection - limitations of stress testing in left ventricular dysfunction

Incidental diagnosis of left ventricular systolic dysfunction (LVD) is common in clinical practice. The prevalence of asymptomatic LVD (Ejection Fraction, EF < 50%) is 6.0% in men and 0.8% in women and is twice as common as symptomatic LVD. The timely and definitive exclusion of an ischemic etiology is central to optimizing care and reducing mortality in LVD. Advances in cardiovascular imaging provide many options for imaging of patients with left ventricular dysfunction. Clinician experience, patient endurance, imaging modality characteristics, cost and safety determine the choice of testing. In this review, we have compared the diagnostic utility of established tests - nuclear and echocardiographic stress testing with newer techniques like coronary computerized tomography and cardiac magnetic resonance imaging and highlight their inherent limitations in patients with underlying left ventricular dysfunction.

Beneficial effects of betaxolol, a selective antagonist of beta-1 adrenoceptors, on exercise-induced myocardial ischemia in patients with coronary vasospasm

Although beta-blockers can not be used for the treatment of vasospastic angina, the effect of beta-blockers with vasorelaxant property on coronary vasospasm remains uncertain. In this study, we evaluated the effect of betaxolol, a new beta-blocker with calcium antagonistic property, as an additional therapy on vasospastic angina (VSA) with anginal attacks on effort. We enrolled 12 patients with VSA and anginal attacks with ST segment depression during exercise stress test. All patients received 1.25-5 mg of betaxolol for 3 months. Treadmill exercise stress test and adenosine triphosphate stress thallium-201 myocardial scintigraphy were performed before and 3 months after the onset of the betaxolol treatment. The other drugs including calcium antagonists, nitrates and nicorandil were continued. No patients experienced the exacerbation of angina during the betaxolol treatment. Exercise time to chest pain (317.5+/-72.1-454.2+/-75.5 s, P<0.01) and maximal ST segment depression (1.67+/-0.67-1.16+/-0.46 mm, P<0.01) obtained by exercise stress test, the defect score (8.6+/-2.7-5.3+/-2.1, P<0.01), the extent score (14.8+/-5.8-8.8+/-4.6%, P<0.01), the severity score (17.5+/-7.3-11.3+/-5.2, P<0.01) and washout rate (31.4+/-5.6-37.6+/-5.0%, P<0.01) obtained by the scintigraphy were improved by betaxolol. Our results suggest that betaxolol increases regional myocardial blood flow and improves exercise capacity in patients with VSA. Betaxolol may become a drug for a new potential therapy for VSA.

Sudden cardiac death from coronary artery spasm in a healthy subject

The true incidence of sudden cardiac death (SCD) from coronary artery spasm is unknown. The following case involves SCD in a previously asymptomatic young man with reasonable evidence to implicate coronary artery spasm as a potential cause for his clinical event. Ergonovine provocation may be warranted in patients who present with SCD and no discernable cause.

Calcium channel blockers cannot prevent pure vasospastic myocardial infarction

Coronary artery spasm is a recognized cause of myocardial infarction. This report describes a case of myocardial infarction attributed to pure coronary spasm which was halted by a double perfusion with streptokinase and nitroglycerin. Further coronary artery spasm leading to a myocardial infarction could not be avoided several weeks later, although the patient was left on calcium channel blocker therapy. The two attacks were not preceded by warning angina pectoris, contrary to accepted belief. The best objective of end-point drug therapy and its assessment in vasospastic angina are discussed.

Diagnosis of important fixed coronary stenosis in patients with variant angina by exercise tests after treatment with calcium antagonists

A 12 lead electrocardiogram was recorded during treadmill exercise in 57 patients with variant angina in whom coronary angiography was performed. Thirty six patients performed exercise tests with and without calcium antagonists, and 21 performed them only with calcium antagonists. In 55 patients calcium antagonists had prevented spontaneous attacks of variant angina for more than two days before the test. The other two patients were given a single dose of diltiazem (90 mg) two hours before the test. Exercise testing without calcium antagonists induced ST segment elevation with chest pain in nine patients, ST segment depression in 10 (nine with chest pain), and no important shift of the ST segment in 17. Five patients had severe coronary stenosis (greater than or equal to 75%) and all of them showed positive response. Thirty one patients had no important coronary stenosis and 14 of them showed positive response. The sensitivity of the exercise test in detecting a coronary stenosis greater than or equal to 75% was 100% without calcium antagonists but the specificity was low (55%). When the exercise test was done in patients taking calcium antagonists, only two (specificity 96%) of 48 patients without severe coronary stenosis showed positive response (elevation of ST segment in one and depression in another) whereas all nine patients with severe coronary stenosis had a positive response (depression of ST segment in six and elevation in three (sensitivity 100%). It is concluded that exercise testing with calcium antagonists may be a useful method for detecting severe coronary stenosis in patients with variant angina.

Coronary artery spasm and cardiac arrest in carcinoid heart disease

Previously reported cardiac manifestations of carcinoid disease include right-sided valvular dysfunction and vasomotor disturbances. This report describes a 62-year-old white man who had electrocardiographically documented widespread elevation of the S-T segment, arrhythmias, and cardiac arrest after exercise. Noninvasive and laboratory studies confirmed the diagnosis of malignant carcinoid disease with tricuspid valve involvement. Coronary angiography revealed mild atherosclerosis. Thus, coronary artery spasm is a previously unrecognized manifestation of carcinoid heart disease and introduces what may be an important relationship of endogenous, excessive vasoactive amines to human coronary vasospasm.

Verapamil: full spectrum calcium channel blocking agent: an overview

Oral verapamil approved for use in all forms of angina, with its additional heart rate-controlling properties has undergone extensive clinical investigation and use since its initial development and has been demonstrated to be safe, well-tolerated and effective over a broad range of cardiovascular disorders. Further potential therapeutic indications for verapamil use remain to be assessed. Additional research with this exciting drug is ongoing.

Exercise-induced ST segment elevation in a patient with effort angina pectoris and normal coronary arteries

A 32 year old woman who complained of exercise-induced chest pain was found to have widespread elevation of the ST segment of the electrocardiogram during exercise testing. Coronary angiography demonstrated no obstructive lesions and no evidence of coronary artery spasm despite ergonovine administration, bicycle ergometry and rapid atrial pacing. Exercise thallium-201 scintigraphy demonstrated no perfusion defects despite ST segment elevation. Radionuclide blood pool imaging revealed a slight decrease in ejection fraction with exercise. The available evidence raises the possibility of small vessel coronary artery disease, either structural or vasotonic, as a cause of this patient's symptoms.

Clinical studies of patients with coronary spasm

Coronary artery spasm may cause myocardial ischemia in patients without severe coronary atherosclerotic obstruction. Spontaneous rest angina, particularly at night, is the predominant symptom; most patients are smokers. Ergonovine tests have high sensitivity and specificity for the diagnosis of coronary spasm, but should be used when vasospasm is suspected but no electrocardiogram was recorded during spontaneous angina. Arterial constriction measured during ergonovine testing suggests that the arterial hypersensitivity to vasoconstrictors at sites of atherosclerotic lesions is independent of the severity of the lesion. Coronary vasospasm may also be provoked by exercise, possibly through an alpha-adrenergic mechanism. Both spontaneous and exercise-induced attacks of vasospasm are prevented by calcium-antagonist drugs that remain effective during longer-term treatment. The cyclic nature of the condition is demonstrated when successful therapy is discontinued without recurrence of symptoms and may be due to alteration of arterial hypersensitivity.

Treatment of angina pectoris with nifedipine: importance of dose titration

The effects of different doses of nifedipine on frequency of angina and objective measurements of myocardial ischaemia during exercise were studied in 10 patients with stable angina pectoris. In a single blind trial over nine weeks patients received one week's treatment each with placebo, nifedipine 10 mg, 20 mg, 30 mg, 40 mg, 30 mg, 20 mg, 10 mg, then placebo three times a day. The response to the different doses of nifedipine was highly variable. On exercising, three patients achieved a consistent improvement in workload attained before onset of ST segment depression and maximum ST depression during exercise testing during all active phases. Four patients improved with 10 mg three times a day but deteriorated at higher doses. In two patients there was no objective or subjective improvement with any dose of the drug, while in one patient anginal frequency increased and there was objective deterioration during exercise testing at doses above 10 mg three times a day. Thus a dose of nifedipine that is beneficial in one patient may have minimal or opposite effects in another. These results indicate the importance of careful titration of doses for individual patients if the maximum benefit from nifedipine is to be obtained in patients with exertional angina.

Calcium antagonists. Clinical use in the treatment of angina

Angina pectoris results from an imbalance between the oxygen supply and the oxygen needs of the myocardium. While the classic form of angina is usually caused by demands exceeding supply, a primary and transient decrease in coronary blood flow is more and more often recognised as an aetiological factor of myocardial ischaemia. Calcium antagonists, although new in cardiovascular therapeutics, are already recognised as the treatment of choice for some forms of angina and as useful therapeutic adjuncts in others. Few contraindications to their use exist. They are potent vasodilators and they can prevent the occurrence of coronary artery spasm responsible for the Prinzmetal's variant form of angina. They can also reduce coronary artery tone, which if high, can compromise flow through a narrowed coronary artery. Nifedipine, diltiazem and verapamil can also influence the various determinants of myocardial oxygen consumption to reduce myocardial oxygen needs. Their effects on heart rate, blood pressure and on the inotropic state of the left ventricle is, in vivo, the balance between their direct effects on the vascular wall and myocardial muscular cells and their indirect effects represented by the reflex physiological responses. Significant variations in these effects exist between the 3 calcium antagonists such that treatment can be individualised to a particular patient's needs. Precautions with their use as well as most of their side effects can be understood from a knowledge of their direct and indirect properties. Other pharmacological effects of these drugs include a regional redistribution of coronary blood flow, cardioprotection, delay in cell death and possibly in the progression of atherosclerosis. The clinical significance of these properties remains to be investigated.

Variable threshold exertional angina in patients with transient vasospastic myocardial ischemia. Repeat exercise test results and therapeutic implications

Thirty-five of 70 patients with vasospastic angina at rest complained of chest pain during exercise or during usual daily activity. In 22, the angina threshold was described as variable during exercise: that is, the amount of exertion that induced angina was not always the same. In 12 patients with variable threshold exertional angina, 3 exercise tests performed in the morning on different days yielded different results, because chest pain and ischemic electrocardiographic changes occurred at different work loads with a wide range in heart rate-systolic pressure product. Two patients, in whom great cardiac vein flow was measured during exercise before and after taking nifedipine, tolerated heavier work loads after receiving the drug, with a more marked increase in flow during exercise. It is concluded that variable threshold exertional angina can be objectively demonstrated by repeat exercise tests in patients with vasospastic angina. Variability of the angina threshold may be due to a functional mechanism that causes myocardial ischemia in addition to the increased myocardial metabolic requirements provoked by exercise. Because in such patients fluctuations in coronary arterial tone play an important role in determining the response to exercise, calcium antagonistic drugs, which lower coronary tone and prevent the occurrence of coronary spasm, are effective in increasing exercise capacity.

Clinical value of calcium antagonists in treatment of cardiovascular disorders

All calcium antagonists have the ability to decrease the symptoms and signs in some patients with ischemic heart disease and help lower the blood pressure in hypertensive persons, but in clinical doses nifedipine does not exhibit antiarrhythmic properties, although these are an important part of the action of verapamil, diltiazem and some substances with a similar chemical structure. In certain disorders beta-adrenergic blocking drugs are useful adjuncts, and under some circumstances, particularly variant angina and supraventricular arrhythmias, specific calcium antagonists are the drugs of choice. More data are needed to define the role of calcium antagonists during cardiopulmonary bypass, in the protection of the ischemic myocardium, in the management of hypertrophic cardiomyopathy and in specific cases of primary pulmonary hypertension. When used with an appropriate sense of perspective and careful observation, calcium antagonists provide useful additional means of helping selected patients suffering from particular cardiovascular diseases.

Verapamil hydrochloride: pharmacological properties and role in cardiovascular therapeutics

Verapamil hydrochloride, a prototype calcium antagonist, is now marketed in the United States for the acute treatment of supraventricular tachyarrhythmias and for chronic management of vasospastic and chronic stable angina. It inhibits the slow inward channel in in the heart and blocks calcium influx in smooth muscle. Its intrinsic negative inotropic action, which is apparent in isolated tissues, is offset in vivo by peripheral vasodilation. It has a mild, noncompetitive sympathetic antagonist effect; its most important electrophysiologic action is a depression of AV nodal conduction, accounting for its effect in supraventricular tachyarrhythmias. Its hemodynamic actions are characterized by a complex interplay of changes in preload, afterload, contractility, heart rate, and coronary blood flow. It does not depress cardiac function, except in severe heart failure. The drug has a mild dilator action on coronary arteries and reverses ergonovine-induced vasoconstriction. Controlled trials have established its role in Prinzmetal's variant angina, unstable angina, and chronic stable angina. It has also been found to be effective in obstructive cardiomyopathies. The potential role of verapamil in such conditions as hypertension, cardioprotection, and Raynaud's phenomenon needs further evaluation; at present these indications have not been approved by the Food and Drug Administration. The most common side effects include constipation, skin rash, and dizziness; AV block, heart failure, and sinus arrest may occasionally be encountered, especially when ventricular function is compromised or conduction system disease is present.

Long-term follow-up of verapamil and nitrate treatment for coronary artery spasm

Thirty-seven patients with coronary artery spasm and minor coronary atherosclerosis (34) or normal coronary arteries (3) were followed up long-term. All had angina at rest, 32 had nocturnal angina, and 13 had a positive exercise test with S-T elevation. Three had a previous subendocardial infarction; 10 had had serious arrhythmias, which caused syncope in 7. At last review, 21 months (range 1 to 61) after starting therapy, 27 patients continued on verapamil, 314 (120 to 600) mg/day; 4 who did not respond to verapamil were taking nifedipine, 58 (30 to 80) mg/day; and 16 were also taking isosorbide dinitrate, 41 (20 to 80) mg/day. Of the 31 patients on therapy, 21 were asymptomatic, 9 were improved (1 to 4 attacks/month), and 1 had an average of 8 anginal attacks/month; the remaining 6 had stopped therapy and 5 were asymptomatic a mean of 10 (3 to 18) months after stopping. The exercise test became negative in all 12 patients tested on therapy, although 3 required nitrates in addition to verapamil or nifedipine. In 26 supervised treatment withdrawals in the hospital, a mean of 15 (1 to 55) months on therapy, 10 developed angina in less than 48 hours. Angina recurred in all 6 unsupervised, patient-initiated withdrawals. Failure to stop smoking was positively associated with recurrence of angina on treatment withdrawal (p less than 0.02). Long-term treatment of coronary artery spasm with verapamil or nifedipine together with isosorbide dinitrate was well tolerated and effectively relieved angina. No documented serious arrhythmias, syncopal episodes, myocardial infarction, or death occurred during follow-up.

Calcium antagonists in the treatment of individuals with ischemic heart disease

The so-called calcium antagonists--verapamil, nifedipine, diltiazem, and perhexiline--are pharmacologic agents that will have a dramatic impact on the medical therapy of individuals with ischemic heart disease. They have been used extensively in Europe and Japan for over 15 years, and more recent studies from this country have demonstrated their efficacy in the treatment of patients with Prinzmetal's "variant" angina pectoris, stable (exertional) angina pectoris, and unstable angina pectoris. In addition, they appear effective in protecting ischemic myocardium both in patients with acute myocardial infarction as well as in those undergoing cardiopulmonary bypass. The purpose of this review is twofold: (a) to describe the mechanism of action and pharmacology of these agents and (b) to delineate their role in the treatment of individuals with ischemic heart disease.