Diagnosing a heart attack early is important in view of the fact that with each passing minute, more heart tissue is damaged and the prognosis worsens. The doctor is strongly aware of this and has to act quickly to detect the heart attack as early as possible.
Heart attack symptoms in women are less obvious and more likely to be missed. Women also suffer milder attacks, which may be missed on the ECG or any other standard tests.
Though the tests to diagnose a heart attack are the same for men and women, blood tests to detect a protein called cardiac troponin is very sensitive and specific and helps to diagnose a heart attack in men and women, which has been missed on other tests.
Classic symptoms of chest pain or discomfort, shortness of breath, breaking out into cold sweats, nausea and/or light-headedness can pretty much nail the diagnosis.
However, not all patients of heart attack experience classic symptoms, which at times may be vague.
At times, there may no chest pain nor any other symptoms. This is called a silent heart attack. At such times, symptoms do not help much to detect the heart attack. The family history of a heart attack can make the doctor strongly suspicious.
Similarly, presence of risk factors such as smoking, high blood pressure, diabetes, high cholesterol levels in the blood, obesity, a sedentary lifestyle, will make your doctor want to investigate you for a heart attack, and he will not lose any time with the investigations and tests to confirm the diagnosis of your heart attack.
Tests described below will help your doctor to confirm the diagnosis of a heart attack even in case of a silent heart attack.
Tests to diagnose heart attack
An ECG, also referred to as an EKG, is the first thing the doctor takes of the patient suspected of having a heart attack, for the simple reason that it is painless and available next to his table and takes only a couple of minutes to perform.
Results are available immediately. Portable ECG machines are also available, which the doctor can carry if on a visit to the patient’s residence.
Electrodes are attached to the skin of your chest, arms and the legs and the electrical impulses of the heart are recorded, which are displayed on the monitor screen or on paper.
As ECG records the electrical activity of the heart. It shows the rate at which the heart is beating and its rhythm, whether it is regular or irregular. It also records the force and the timing of the electric impulse as it travels through each part of the heart.
Since heart muscle damaged by a heart attack does not conduct the electric impulses in a normal fashion, it shows on the printed result paper of the ECG.
Besides showing the damage caused by a heart attack, it also shows whether there are any signs of a previously missed heart attack.
However, in 20 percent of the cases, the ECG fails to detect a heart attack even though it is present.
Chest x-ray helps to see the size of the heart, whether it is normal or enlarged. It also helps to visualize the main arteries, which emerge or enter the heart.
It will help to detect the presence of any fluid in the lungs (pulmonary edema), which can be caused by coronary artery disease, heart failure, and other heart conditions.
Laboratory blood tests for enzymes
The blood will be tested for lipid profile to check whether the cholesterol (both HDL and LDL) and triglycerides are elevated or not.
Other lab blood tests to diagnose a heart attack are done based on the fact that damage to heart muscle due to a heart attack causes the release of certain enzymes or proteins into the blood from the heart muscle.
Blood tests that detect the presence of these proteins in the blood will indicate heart muscle damage. The specific proteins that are tested for include:
Creatine kinase (CK)
Creatine kinase-MB (CKMB)
Cardiac troponin I or cardiac troponin T
However, some of these proteins namely CK, CKMB, and myoglobin are also found in other muscles. They are therefore not specific to the heart and their levels can be elevated when these other muscles are also damaged.
A new test to detect the protein cardiac troponin is more sensitive and specific to heart muscle damage since cardiac troponins are found only in the heart and not in any other muscles.
However, there is a time lag between the onset of heart muscle damage and the presence of cardiac troponins in the blood. Current guidelines recommend that the blood be tested several times for these proteins over 8 to 12 hours after the patient has been admitted in the hospital.
The absence of the above-mentioned proteins in the blood does not indicate an absence of heart disease but only absence of heart damage. Further testing is necessary in such cases.
An echocardiogram also called echocardiography or diagnostic cardiac ultrasound is a harmless test in which sound waves directed at the heart bounce off and are recorded electronically to provide detailed video images of the heart.
The sound waves are directed to the heart by a transducer, which is placed over the chest and captures the bounced sound waves.
An echocardiogram provides details of the damage suffered by the various parts of the heart including the heart’s chambers, valves, walls and the blood vessels (aorta, arteries, and veins).
It can be done during and after the heart attack to determine the damage to the heart and gauge its function of pumping blood.
Exercise stress test
An exercise stress test sometimes called a treadmill test (TMT) or just an exercise test gauges how well your heart functions during physical stress or exertion. You are made to walk on a treadmill or to pedal on a stationary bike, which is connected to an ECG machine. It is done sin the presence of medical professional.
During increasing stress, your heart and the body require more oxygen and, therefore, your heart has to work harder to pump out more blood.
This test monitors the heart rate, respiratory rate, and blood pressure during different levels of the stress.
The test helps the doctor know if the blood supply to the heart during stress is reduced. It also helps to know the stress threshold of the patient – in other words the level of exercise appropriate for the patient.
Angiogram or coronary catheterization
This imaging test helps to visualize the coronary arteries directly on x-ray and helps the doctor to know the presence and the amount of blockage in the arteries.
Procedure: A catheter, which is a long thin tube is inserted into an artery, either in your groin or the leg. It is then guided under vision on x-ray on a video screen. This is called fluoroscopy and it helps to see the catheter as it is guided through the arteries to the desired artery.
Once the catheter is in the desired position, the physician inserts a contrast dye, which is visible on x-ray. As the dye flows though the coronary artery, images are taken, which help to see the blockage in the artery, if any.
The dye is later eliminated by the body through your urine.
Cardiac computerized tomography (Cardiac CT) or magnetic resonance imaging (Cardiac MRI)
These tests help to diagnose the heart problems and also evaluate the extent of damage due to a heart attack.