In-Vitro and In-Vivo Diagnostics and Therapy of Coronary Artery Disease
Lab testing and different imaging modalities provide complementary information for assessment of the cardiac status and therefore play an increasingly important role in the management of patients with coronary artery disease.
Echocardiography
Echocardiography is the basic imaging modality in Cardiology. In CAD patients echocardiography is capable to analyze the relevant clinical questions:
• Cardiac Anatomy & Morphology
• Myocardial Function under rest and stress condition
• Myocardial Perfusion
• Myocardial Viability
(Appropriateness Criteria for Stress Echocardiography1)
Invasive Cardiology
CAD leads to progressive plaque formation with secondary limitation of the myocardial blood flow, when the stenosis is >60%. So evaluation of the coronary status is of great value in the management of CAD patients. Coronary angiography is still the gold standard for evaluation of the coronary lumen. It can be performed in every patient independent of rhythm and heart rate. It offers the immediate possibility to restore normal coronary blood flow in cases of high grade coronary stenosis or to re-open an occluded vessel.
Cardiovascular CT
Over the last years CT has become a valuable diagnostic tool for evaluation of the heart, especially the coronary arteries in all day clinical routine. Developments like Dual Source CT are overcoming initial limitations of cardiac CT like heart rate dependency and radiation dose. Recent studies show that Coronary CTA performed with a Dual Source CT may contribute to increase quality of care.(2)
Cardiovascular MR
Cardiovascular MR (CMR) has become a routine diagnostic tool for state of the art comprehensive evaluation of patients with cardiac disease. In CAD, CMR supports clinical decision making by providing information related to
• Cardiac anatomy & tissue morphology
• Regional and global myocardial function
• Myocardial function
• Myocardial perfusion
• Myocardial viability
• Coronary status
(Appropriateness Criteria for Cardiac CT and Cardiac MRI 2)
Nuclear Cardiology
Nuclear cardiology is well established since over 30 years and nowadays mainly used to assess myocardial perfusion, viability and function in addition to:
•SPECT (Single Photon Emission Computed Tomography) and
•PET (Positron Emission Tomography)
Hybrid systems allow to combine the functional imaging of SPECT / PET with the anatomical imaging of CT. This increases diagnostic accuracy and reduces acquisition time significantly. (Appropriateness Criteria for SPECT MPI3)
Laboratory Testing in CAD
Diagnostic strategies for managing patients with chest pain have improved tremendously with the use of biomarkers, such as cardiac troponins. Their intended use has expanded from its original one as an aid in the diagnosis of acute myocardial infarction (AMI) to include risk stratification of patients with ACS with respect to their relative risk of mortality and therapy orientation / monitoring. Cardiac troponins indicate myocardial necrosis and not just MI.(4,5) In fact, troponin elevations can reflect various causes of myocardial necrosis, even outside of an ischemic context(6), and should therefore not automatically be perceived as “false positives”. Moreover, elevated troponin levels offer high* prognostic value, irrespective of the cause.
Natriuretic peptides (NPs) indicate cardiac hemodynamic stress, as observed in heart failure. NPs are predominantly secreted from the ventricle in response to myocardial wall stress. They both have high sensitivity and specificity for cardiac function. Blood levels correlate with severity of cardiac heart failure, thus providing an indication for patient prognosis.
External References
1) ACCF/ASE/ACEP/AHA/ASNC/SCAI/SCCT/SCMR, J Am Coll Cardiol, 2008; 51:1127-1147
2) ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR, J Am Coll Cardiol, 2006; 48:1475-1497
3) ACCF/ASNC, J Am Coll Cardiol, 2005; 46:1587-1605
4) Morrow DA, et al. Clin Chem. 2007;53:552-74.
5) Thygesen K, et al. J Am Coll Cardiol. 2007;50:2173-95.
6) Wu AHB, et al. Clin Chem. 2007;53:2086-96.
Legal Information
A) LAD stenosis 50%, SOMATOM Definition, Courtesy of Friedrich-Alexander University Erlangen-Nuremberg, Germany
B) PET•CT (biograph 64) perfusion study demonstrating irreversible lateral defect, Courtesy of Emory Crawford Long Hospital, Atlanta, USA
