Principles of diagnsosis of ischemic heart disease Mohammad Hashemi Interventional cardiologist Department of cardiology.

Principles of diagnsosis of ischemic heart diseaseMohammad Hashemi

Interventional cardiologist

Department of cardiology

Ischemic chest pain due to coronary artery disease (CAD)

stable angina pectoris, unstable angina, non-ST elevation myocardial infarction, and ST elevation myocardial infarction.

The differential diagnosis of patients presenting with chest pain is extensive

Ischemic chest pain due to coronary artery disease Patients classically complain of chest heaviness,

pressure, tightness or burning, but may vigorously deny "pain.

Other descriptions such as provocation with physical or emotional stress or cold, relief with rest, and radiation to the neck, jaw, and shoulder are common.

Ischemic pain usually lasts more than 2 but less than 20 minutes, unless a myocardial infarction is occurring.

Associated symptoms may include dyspnea, nausea and vomiting, diaphoresis, presyncope, or palpitations.

The correct diagnosis is based on

detailed history (pain description; associated symptoms; and in some cases disease risk factors) that is

supported by specific physical findings,

an electrocardiogram, and/or chest x-ray.

EVALUATION

The office evaluation of new onset chest pain in stable individuals should begin with the consideration of imminently life-threatening causes (including acute coronary syndrome, pulmonary embolus, aortic dissection, pneumothorax, and esophageal rupture).

This is usually accomplished using clinical judgement, along with ECG testing, and less frequently exercise testing, other noninvasive testing, or invasive angiography.

The clinical evaluation is also useful to estimate the pretest probability of organic causes of chest pain prior to undergoing diagnostic tests (eg, stress ECG testing to detect CHD or d-dimer, CTa-angiography or lung perfusion scanning to detect pulmonary embolism).

Pretest probability is an important component of the interpretation of these test results.

The history typical chest pain is less useful in patients suspected of having an acute coronary syndrome (ACS)

Conversely, in patients with stable, intermittent chest pain, a description of typical angina (ie, substernal discomfort, precipitated by exertion, improved with rest or nitroglycerin in less than ten minutes with many patients reporting radiation to shoulders, jaw, or inner arm) was a moderately strong predictor of obstructive epicardial CHD .

Description of chest pain 

Descriptions of chest discomfort due to myocardial ischemia may differ depending on: patients' culture,

gender,

age

and presence of comorbid conditions such as diabetes.

Quality of the pain

Region or location of painRadiationProvocationSeverity Palliation

Associated symptoms

Belching, Belching,

Vomiting

Diaphoresis

Dyspnea

Cough

Syncope

Palpitations

Psychiatric symptoms

Constitutional symptoms —particularly in elderly may describe profound fatigue.

Risk factors

  The clinical impression raised by the patient's description of pain must be interpreted together with other aspects of the history, including risk factors for various etiologies of chest pain

Risk factors

A history or lack of classical coronary risk factors does not usefully discriminate ischemic causes of chest pain in the acute setting

Physical examination

A brief, "core" examination may suffice to diagnose life-threatening and common etiologies of chest pain. The general appearance

A full set of vital signs

Palpation of the chest wall may evoke pain

A complete cardiac examination including auscultation and palpation

Determine if the breath sounds are symmetric

A careful examination of the abdomen is important

Focal neurologic signs

Electrocardiogram

Normal electrocardiogram A normal ECG markedly reduces

the probability that chest pain is due to acute myocardial infarction, but it does not exclude a serious cardiac etiology (particularly unstable angina).

Abnormal electrocardiogram

The ECG is valuable both for risk stratification and diagnosis of acute myocardial infarction.

Stress testing for the diagnosis of coronary heart disease

The major questions to be addressed before selecting one or more of the available diagnostic tests are:

What is the patient's pretest risk of CHD?

How accurate are the alternative tests?

What are the costs and effects on health outcomes of each test?

Do special considerations make one test more suitable in a specific patient?

PRETEST PROBABILITY

An initial estimate of the likelihood of CHD is based upon the clinical history.

The pretest probability determines the need for noninvasive diagnostic tests or even coronary arteriography

Estimating pretest probability

Definite or classic angina — Substernal chest discomfort characterized by all of the following characteristics: a typical quality and duration, provocation by exertion or emotional stress, and relief by rest or nitroglycerin

Probable or atypical angina — Chest pain with two of the three above characteristics

Nonanginal or nonischemic chest pain — Chest pain with one or none of the above characteristic

Estimating pretest probability

 It should be noted that asymptomatic patients have a low pretest probability of significant CHD, and generally are not screened by use of stress testing.

Symptomatic patients with moderate risk of CHD may be considered for stress testing .

NON-INVASIVE TESTS

Exercise ECG testing is the most commonly used noninvasive test because it is simple and inexpensive.

Echocardiography using either exercise or pharmacologic (dobutamine or dipyridamole) stress.

Radionuclide myocardial perfusion imaging using either exercise or pharmacologic stress.

Women

Diagnosing coronary artery disease is more difficult in women than men for the following reasons: Women are less likely to present with (or report

during treadmill testing) typical angina.

False positives test results during exercise ECG testing are more common.

Limitations of exercise stress

The exercise ECG cannot be interpreted in the presence of resting ST segment changes, left ventricular hypertrophy, left bundle branch block, a ventricular paced rhythm, or the Wolff Parkinson White syndrome.

The patient must also be able to exercise adequately,

Exercise ECG testing is the most commonly used noninvasive test because it is simple and inexpensive.

INVASIVE TESTS

Coronary angiography is the definitive diagnostic test for the presence of obstructive coronary artery disease.

However, it is seldoam used as the initial test because of its invasive nature and because the presence of a lesion does not prove that the patient's symptoms are due to ischemia.