Silent myocardial ischemia - this term is used when there are no symptoms of myocardial ischemia, despite the fact that its features have been found in objective diagnostic tests. The presence of an asymptomatic form of coronary artery disease may cause diagnostic difficulties and worsen the prognosis.

Silent myocardial ischemia , without pain or its "masks", seems to be a very common problem. It is difficult to accurately estimate the frequency of this phenomenon, but it is assumed that as much as 50-80% of all ischemic episodes can be painless!

In 1981, it was proposed to divide patients with asymptomatic ischemia into 3 types:

  • type 1 - the rarest, completely asymptomatic;
  • type2 - patients with no symptoms and a history of myocardial infarction;
  • type3 - the most common; patients with symptomatic coronary artery disease, but presenting episodes of silent ischemia.

Coronary artery disease is a group of clinical symptoms associated with myocardial ischaemia due to the limited blood flow through the coronary arteries, which transport oxygen and nutrients to the heart. The most common cause of this condition is atherosclerosis. Coronary artery disease can present as a stable form - angina (angina) or acute (e.g. myocardial infarction). The most characteristic symptom of myocardial ischemia is chest pain. Its typical features (in stable form) are:

  • overseas localization,
  • occurring under the influence of exercise or stress,
  • retirement.

Sometimes typical pain may not occur, and the patient struggles with similar ailments, e.g. shortness of breath, palpitations, fainting, abdominal pain, nausea, etc.

Silent myocardial ischemia: causes

The etiology of silent myocardial ischemia has not been clearly explained, although many hypotheses have emerged over the years to explain this phenomenon. A large role was assigned to diabetes, and more specifically to the autonomic neuropathy appearing in its course. It is in this group of patients that the so-called painless heart attacks. The causes of silent ischemia are also believed to be, among others, individualdifferences in the perception of pain, higher production of beta-endorphins reducing its intensity, the effect of inflammatory cytokines on the increase of the pain threshold and platelet microembolisms in the smallest vessels of the coronary circulation.

We can distinguish certain factors that increase the likelihood of asymptomatic ischemic episodes:

  • diabetes
  • hypertension
  • old age
  • recent heart attack
  • kidney failure

Silent myocardial ischemia: diagnosis

Due to the high frequency of asymptomatic cases of coronary artery disease, it is crucial to estimate the probability of its occurrence based on risk factors such as: older age, family history, smoking, obesity, diabetes and dyslipidemia. Increased vigilance allows for earlier implementation of more specialized diagnostics.

The basic tests used to detect ischemia are:

  • 24 (or 48) hour Holter monitoring of the ECG - continuous ECG measurement creates a better chance of documenting silent ischemic episodes; disposable, resting ECG is usually not very diagnostic in this case.
  • electrocardiographic exercise test - in this method, an ECG test is performed during controlled physical exertion, e.g. on a treadmill, in order to provoke and record an ischemic episode.
  • stress tests - they are an alternative and supplement to stress tests; an example is the trial with dobutamine, the pharmacological action of which is to increase the heart rate. Hypoxia-induced contractility disorders can be visualized by echocardiography (ECHO of the heart).

Less frequently performed tests include: exercise perfusion scintigraphy and positron emission tomography (PET).

Silent myocardial ischemia: treatment

Treatment is no different from that for symptomatic coronary artery disease. The basic (and probably the most difficult) element of the procedure is the modification of risk factors, which primarily includes:

  • making appropriate changes to the diet
  • regular, appropriately adjusted physical exertion
  • quit smoking

Treatment and compensation of carbohydrate and lipid disorders

Pharmacotherapy is primarily drugs that improve the prognosis and reduce the risk of cardiovascular events: acetylsalicylic acid, statins, convertase inhibitors and drugs that reducefrequency and severity of symptoms: beta-blockers, calcium channel blockers and nitrates.

In cases where pharmacological treatment is inadequate, and the arteries have significant or critical stenosis, coronary revascularization is the method of choice. It can be a transvascular procedure (PCI) - usually involving the introduction of the so-called stent in place of the stenosis. Sometimes surgical revascularization is also recommended - aorto-coronary bypass, i.e. popular "by-passes".

This will be useful to you

Silent myocardial ischemia: prognosis

Episodes of silent heart ischemia can occur both in patients diagnosed with coronary artery disease who also have typical symptoms, and in those who have never reported any symptoms. It is in the latter group that they are more dangerous. They increase several times the risk of such events as heart attack, sudden death or stroke. A cardiovascular event may then be the first symptom of a long-term and unrecognized coronary artery disease. The lack of coronary pain prevents the unaware of the disease from going to the doctor. The process of diagnosis and treatment implementation is delayed. For this reason, it is so important to know risk factors and take preventive measures to diagnose ischemic heart disease at an early stage.

Sources:

1. Anna Kazik, Lech Poloński, Silent myocardial ischemia - still many question marks, "Diseases of the Heart and Vessels" 2007, vol. 4, no. 3, 117-122 (online)

Category:

Cardiology