Airway hyperresponsiveness in patients with microvascular angina. Evidence for a diffuse disorder of smooth muscle responsiveness.

Abstract

Anginal chest pain in patients with angiographically normal coronary arteries may be caused by a limited coronary flow response to stress because of abnormal function of the coronary microcirculation (microvascular angina). Studies of forearm arterial function suggested that patients with microvascular angina may have a diffuse disorder of smooth muscle tone. Because dyspnea is common in these patients and seems disproportionate to the severity of myocardial ischemia, we studied air flow (forced expiratory volume in 1 second, or FEV1) in the basal state and after methacholine inhalation to determine whether bronchial smooth muscle is affected in this syndrome. Five of 36 patients with microvascular angina had a basal FEVy of less than 70% of that predicted and did not receive methacholine. Of the remaining 31 patients, 14 (45%) had a more-than-20% reduction in FEV1 after methacholine inhalation (as much as 25 mg/ml), a response significantly greater than that of nine patients with heart disease (0%, p<0.025) and 24 normal volunteers of similar age and gender distribution (13%, p<0.025). Furthermore, the product of the methacholine dose inhaled and the magnitude of decline in FEVY from baseline (methacholine response score) was significantly lower in patients with microvascular angina than in normal volunteers (16±8.6 versus 22.2+3.7, p=0.026). We conclude that airway hyperresponsiveness is frequently demonstrable in patients with microvascular angina; these findings are consistent with our hypothesis that this syndrome may represent a more generalized abnormality of vascular and nonvascular smooth muscle function. (Circulation 1990;82:2011-2017 Approximately 10-30% of patients with anginalike chest pain exhibit no large vessel coronary artery disease at catheterization and have no other myocardial or valvular cause for the pain.1,2 We have found that many of these patients have a dynamic abnormality in coronary flow caused by increased coronary resistance of vessels too small to be imaged angiographically and have applied the term "microvascular angina" to denote this syndrome.3-8Many patients with microvascular angina experience breathlessness during physical or emotional stress. However, the severity of myocardial ischemia during stress appears relatively mild and unlikely to explain this symptom. Of note, studies of forearm From the Cardiology Branch, National Heart, Lung, and Blood Institute, and the Allergy

Regulation of Coronary Microvascular Resistance in Health and Disease

“…Furthermore, ST segment changes during stress testing have historically been classified as false positives when they coincide with normal angiographic vasculature, and their concurrent chest pain has sometimes been classified as of non-cardiac origin including psychosomatic disorders and altered pain perception [181][182][183][184][185][186] . Studies by this group also revealed systemic smooth muscle disorders in the esophagus, bronchus, and systemic arteries [195][196][197] in this unique patient population indicating the possible involvement of a diffuse smooth muscle disorder. [175] in which they described a group of women who complained of chest pain with ECG changes during exercise testing and yet had angiographically normal coronary arteries.…”

Role of the vascular endothelium in patients with angina pectoris or acute myocardial infarction with normal coronary arteries

“…These same authors also demonstrated that some patients with microvascular angina may have a generalised disorder of vascular and nonvascular smooth muscle function 13. Finally, some authors suggested a possible link between hyperinsulinaemia and microvascular dysfunction 14…”

Airway Hyperresponsiveness in Patients With Coronary Spastic Angina Relationship Between Coronary Spasticity and Airway Responsiveness

“…[37][38][39] The differences between these 2 agents regarding their receptor distribution and ability to induce endothelium-derived vasodilation or constriction of arterial smooth muscles may be involved in the different results obtained in the present study and those of Saitoh et al 24 Because ACh and MCh challenges have been reported to yield similar high levels of sensitivity and specificity for revealing airway hyperresponsiveness, we consider that the differences between these 2 agents did not affect our results. 40 Influences of age, 41 sex, smoking habits, 42 allergic factors, [43][44][45] left ventricular ejection fraction 46 and microvascular angina 47 on airway hyperresponsiveness have been reported. However, no significant differences were observed among the present CSA, CP and control groups with respect to age, sex or coronary risk factors, including smoking and allergic factors.…”

“…Airway hyperresponsiveness is frequently encountered in patients with microvascular angina, 47 who experience breathlessness and anginal chest pain during physical or emotional stress with angiographically normal coronary arteries. The possibility that microvascular angina was included in the present CP group was not ruled out.…”