In patients with milder chronic primary MR (Stages A and B), TTE is indicated periodically to evaluate for changes in MR severity, depending on valve anatomy and other considerations, because regurgitation may worsen over time. Because this process may develop slowly, MR can become severe and even lead to LV dysfunction in the absence of symp- toms or clinical signs (Table 4).3,6 2. Symptom onset is a crucial demarcation point in the natural history of MR and also a trigger for intervention. Because symptoms develop gradu- ally, patients may fail to recognize or ignore symp- toms. Natriuretic peptide levels provide objective evidence in patients with chronic severe MR, with elevated levels indicating increased reliance on preload to maintain an adequate forward cardiac Thus, serum natriuretic peptide levels may be helpful in making management decisions about intervention when other data are conflicting. LVEF is used as a key determi- nant of LV function in timing MR intervention. Unfortunately, LVEF is load dependent and often overestimates LV function in MR. Global longi- tudinal strain, although also load dependent, appears more sensitive to LV dysfunction in patients with chronic MR and, as such, might give warning that LV function is declining before LVEF Thus, novel markers of LV systolic function, such as global longitudi- nal strain, may be useful adjuncts in assessing LV function in patients with chronic MR. 7.2.2.4. Diagnostic Testing: Cardiac Catheterization Left ventriculography and hemodynamic measurements are useful when clinical assessment and noninvasive tests are inconclusive or discordant with regard to 1) se- verity of MR, 2) LV function, or 3) the need for surgery.1 Noninvasive imaging is adequate for evaluation of MR in most cases. 