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Updates In The Treatment Of Atrial Fibrillation

New Frontiers in Cardiac Imaging: Cardiac CT Provides diagnostic utility and

clinical applications in cardiovascular disease

Cardiovascular diseases have always been on the rise in the history of mankind and as we go into the future, advances in the field of measurement and treatment of these heart diseases must follow suit. Most of the research goes on in the treatment of the disease today, which is a good sign, but the initial step of diagnosing the disease needs a step-up in its progress. There have been many advances in the imaging techniques today than before enabling precise and non-invasive diagnosis of the disease. Some of them are the Cardiac computed tomography (CT), Cardiac magnetic resonance (CMR), echocardiography, nuclear cardiac stress testing, Cardiac position emission testing. Echocardiography is used to define cardiac functioning. Exercise and pharmacologic nuclear stress testing is widely used for the diagnosis and risk stratification of patients with known or suspected coronary heart disease. Cardiac MR is exceptional for evaluating structural heart disease and cardiac functioning, but not for CHD. Cardiac CT has come out as one of the healthy imaging service.

Cardiac Computed tomography (CT) is originally ‘EMI SCAN’ as it was developed at the research centre of a company called EMI. It was later on called as Computed axial tomography (CT scan). The word tomography comes from Greek tomos (slice) and graphein (write). CT scan is an imaging method utilizing tomography where digital geometry processing is used to produce a 3-dimensional image of the internal parts of an object with the help of a large number of series of 2-dimensional X-ray images which are taken around a single axis of rotation. It gives us a volume of data which can be stored and also manipulated through Windowing. Modern day scanners allow this data to be reframed in numerous planes and even as 3D representations of structures. CT is also used in other fields other than health care.

More than half of the patients have death or myocardinal infarction as the predictor of Coronary artery disease (CAD). Traditional risk-prediction systems often can’t predict the development of CAD in a patient or further complications. Coronary artery ‘Calcium scoring’ CT is used to detect coronary artery calcium. It has its own limitations in not identifying soft and noncalicified plaque which may pose greater risk of CAD. Cardiac CT angiography crosses this barrier and uses intravenous contrast to fill the lumen like the usual invasive, catherer-based angiogram. The increased rotation speed of the gantry and the use of multiple detectors (64-slice CT now) enable imaging of the fast moving coronary arteries.

Cardiac CT can estimate narrowing of the arterial lumen, identify both calcified and non-calcified plaque and characterize the artery wall. Many studies have stated the high sensitivity and specificity of CT for detection of coronary stenosis. The sensitivity was 99% and specificity was 95% of the cardiac CT. This proof of Cardiac CT can clearly distinguish high risk patients from low and moderate risk patients. This high predictive nature of Cardiac CT can strike out disruptive CAD and also the need for angiography.

CT scan is also used to accurately assess the left ventricular function (regional wall motion, ejection fraction, infarct identification) than the gold standard, cardiac MR and also contrast echocardiography. CT is also helpful in the assessment of patients with congenital heart disease. Currently investigations are going on to evaluate the use of CT in the emergency room for the assessment of acute chest pain to rule out obstructive CAD, aortic dissection, pulmonary embolus. CT is not advised as a screening test due to the radiation exposure. However there are a few limitations for cardiac CT.

Cardiac CT has proved to be of immeasurable value and has numerous applications to its credit. It has shown its ability to detect calcified and non calcified plaque, luminous stenosis in coronary arteries. Cardiac CT can become the first test for Symptomatic, low-to-intermediate risk patient to rule out obstructive CAD thanks to its consistent negative predictive power of more than 98%. Cardiac CT is a great boon, which should be used in appropriate clinical settings.