The test that is most helpful in revealing the extent of damage to Helen's heart would be the Echocardiogram. This non-invasive imaging technique uses sound waves to create images of the heart's structure and function, allowing for the assessment of heart damage, including issues with heart walls, valves, and overall heart performance.
While Radionuclide myocardial perfusion imaging can also be useful in assessing heart function and blood flow, an echocardiogram is typically the first-line test for evaluating heart damage. In contrast, Coronary artery bypass grafting (CABG) is a surgical procedure rather than a diagnostic test, and a Venogram is used to examine veins rather than the heart itself.