Abstract
Case history
Ms. M, a 65-year-old lady with controlled hypertension attends her GP appointment. She was recently discharged by the emergency department having presented with central chest pain that radiated to her left arm. This was her second presentation within 6 months. The discharge paperwork noted a normal cardiovascular examination and blood pressure readings. She had an abnormal electrocardiogram showing an acute anterior myocardial infarction, but serial troponin testing was negative. She was referred to the cardiology clinic for further assessment by her GP.
The subsequent coronary angiogram revealed normal coronary arteries. A cardiac magnetic resonance imaging was organised to further evaluate the coronary vasculature and overall function of the heart. The diagnosis was subsequently confirmed as microvascular angina.
Discussion
Obstructive coronary atherosclerosis is the most common cause of myocardial ischaemia. In 50% of patients with controlled angina and 10–15% of the patients presenting with the acute coronary syndrome, coronary angiography reveals near-normal or normal vasculature (Lanza and Crea, 2014; Lanza et al., 2018; Patel et al., 2010).
Microvascular angina is an abnormality of the coronary vasculature that leads to an imbalance of blood supply and oxygenation to the myocardium. This can lead to ischaemia (Park et al., 2015). It may present with features of acute myocardial infarction on electrocardiogram testing. It has been observed more often in female patients. In the past, it has been referred to as Cardiac syndrome X. The typical patient is likely to have risk factors for an ischaemic heart, including diabetes mellitus, hypertension, raised cholesterol and smoking.
The high prevalence of microvascular angina in postmenopausal women has been considered to result from oestrogen deficiency. This deficiency may have a pathogenetic role in women suffering from hypertension and microvascular angina.
Coronary angiography in a patient with microvascular angina and hypertension can show pathological changes. The changes can include reduced blood flow and convoluted coronary arteries. It has been noted that abnormal coronary microvascular dilation, spasm, and endothelial dysfunction, as well as dysregulation of the nervous system may play a part in the pathophysiology of microvascular angina (Park et al., 2015).
The management of microvascular angina can be a challenge. The primary objective in the treatment of stable patients is to reduce symptoms and improve quality of life. This can be achieved with pharmacological measures including the use of anti-anginal medication. Non-pharmacological measures such as modifying risk factors are also important. It is also vital to encourage healthy lifestyle changes. This includes achieving a healthy weight, following a healthy diet, ceasing to smoke cigarettes and improving glycaemic control. Alcohol consumption is another important modifiable risk factor.
Diagnosing and managing microvascular angina can be difficult in primary care. Patients with chest pain undergo routine tests to exclude an acute cardiac event. These include cardiac troponin testing, electrocardiography and chest X-rays. A coronary angiogram is usually normal in microvascular angina and it is not unusual for patients to be told they have no underlying heart disease. The use of cardiac magnetic resonance imaging, stress echocardiograms and acetylcholine provocation in angiography can aid the diagnosis of microvascular angina.
