In the past few decades, the diagnosis of angina has become much easier and more reliable with the advent of modern methods that help both evaluate the severity of angina and have a potential curative effect as a step in many treatment options.
The diagnosis of angina -similar to most other diseases– consists of a gathering enough data for a good medical history, a thorough physical examination and targeted lab tests when they are needed. The physician will usually ask about the nature of symptoms including:
◘ Chest pain or discomfort: A typical anginal pain would feel like squeezing, burning, and less frequently stabbing just behind your breastbone (sternum) which might also be felt in your jaw, neck or left arm.
◘ When it starts and what aggravates or relieves it: A typical anginal pain would start and is usually aggravated by physical and sometimes emotional stress, but it might also be triggered by heavy meals and cold exposure and usually relieved by rest. An anginal pain that isn’t relieved by rest would point towards what is called “unstable angina”, a clinical condition with a greater risk that requires immediate investigations and more aggressive management.
◘ Risk factors for any coronary heart disease: It is important to investigate for risk factors affecting the blood supply to the heart, and they include: family history of the same or similar conditions, consumption of excessive fatty or sugary meals, lack of physical activity and smoking as well as alcohol consumption.
◘ Other heart related symptoms: Your physician will ask about other symptoms such as shortness of breath, excessive sweating, and effort intolerance or previous diagnosed heart conditions or operations.
The general examination
Afterwards, the physician will perform both a general examination and one focused on your cardiovascular function. The general examination includes:
☼ Measuring your weight and your body mass index (BMI): This is a measurement of your weight in relation to your height.
☼ Measuring your waist-to-hip ratio: This is a helpful measurement of abdominal obesity.
☼ Measuring your blood pressure and blood glucose level:
These general examinations are mainly directed towards the identification of high risk groups rather than the disease itself. Stable angina tends to have a completely normal physical examination on presentation, and that’s why the physician usually performs other examinations to exclude additional causes of chest pain, as in muscle pain of your chest wall, which is characterized by being aggravated by breathing rather than effort itself, or heartburn from stomach problems that is usually related to meal frequency.
Investigations for the diagnosis of angina
1. Routine lab investigations:
They are performed when there’s already a high suspicion level that the patient may have angina pectoris, and they include: cholesterol and triglycerides levels, cardiac markers or enzymes to detect any damage that might have occurred. This is because damaged heart cells tend to “leak” their enzymes when they die, thereby increasing their level in the blood.
2. Stress ECG or electrocardiogram:
It is the most routinely used investigation for angina pectoris. A stress ECG measures the electrical activity of the heart, and has various patterns that reflect when the heart is deprived of all or some of its blood supply. The difference between a stress ECG and the ordinary ECG is the application of a physical – and less commonly chemical- stress on the heart muscle, such as running on a treadmill. Since angina pectoris occurs in episodes, a normal ECG performed between the attacks is likely not to show anything abnormal. Therefore, we need to simulate a stress condition to push the heart to its limits and help accentuate any present anginal electrical change.
It is one of the most sensitive tests for the diagnosis of angina, and it consists of sound waves that have specific frequencies and wavelengths that “bounce off” and reflect after hitting tissues. This technique helps doctors visualize the anatomy of the heart and detect and abnormalities in the blood flow to the heart as in the case of narrowing of your coronaries. An echocardiogram may also be performed with the stress ECG to take advantage of the stress applied and determine more accurately any abnormality as well as to visualize the most vulnerable areas of this abnormality.
4. Computerized Tomography (CT) scan:
Although not done as routinely as the previous tests, a CT scan may be requested by your treating physician. It is like an X-ray of the heart but taken at multiple levels or “slices” and helps visualize any abnormal anatomy affecting the blood supply of the heart and any evidence of previous heart attacks that were severe enough to cause the death of a part of the heart, clinically known as myocardial infarction.
5. Cardiac MRI:
Similarly, a cardiac MRI helps visualize the heart anatomically and it is usually requested in some patients who can’t tolerate CT. This is the case of patients with allergic reactions against the contrast material that is usually injected during the CT scan.
6. Nuclear stress test:
This test involves the injection of a radioactive substance into the bloodstream, which is then detected by a special scanner that measures whether the cardiac muscles are taking enough of this radioactive substance -and hence blood- or not. Thus, when a portion of the heart isn’t taking enough of this substance, it means that this portion is “ischemic” or deprived of enough blood supply.
7. Coronary angiogram:
Coronary angiogram remains to be the best, but the most invasive of the previous tests. It is a traditional X-ray of the heart but requires the injection of a dye into the blood vessels of the heart through a catheter.
A catheter is a tube-like structure that is inserted through the blood vessels of your legs (the femoral artery or vein) and less commonly those of your forearm (the radial artery). Then, it goes up the blood stream to the aorta where it injects the dye to take an X-ray afterwards. If your coronary arteries are narrow or occluded, the dye will either stop at a certain site or become narrowed. A coronary angiogram is also a routine step prior to the placement of a “stent” for the treatment of both unstable angina and myocardial infarction or the injection of vasodilators or thrombolytic agents in some cases.