Is a change of the current echocardiographic red flag for left ventricular wall thickness useful in cardiac amyloidosis screening?

Abstract

Abstract Background Cardiac amyloidosis (CA) is a serious and progressive infiltrative cardiomyopathy caused by the extracellular deposition of amyloid fibrils in the myocardium. As new disease-modifying therapies are increasingly emerging, prompt and specific diagnosis is fundamental to avoid treatment delay. Echocardiography is the most often used first-line imaging tool for amyloidosis screening. Left ventricular (LV) wall thickness ≥12 mm and age ≥65 years are major criteria for the suspicion of CA. However, it is very likely that many patients, especially in the early stages of the disease, will not be detected. Reducing the diagnostic wall thickness threshold will certainly increase the sensitivity of the amyloidosis screening. It is to be feared, however, that reduction of the cut-off will lead to a large number of patients being unnecessarily subjected to further testing, and substantially increase costs. Objective We investigated the distribution of interventricular septum thickness (IVS) in patients referred for routine echocardiography with the aim of establishing a wall thickness cut-off value that is assumed to be suitable for targeted amyloidosis screening. Methods We retrospectively analysed the echocardiographic reports from August 2021 to December 2021 at our department. Individual IVS values were documented and categorised. This was to give an idea of how many patients were potentially eligible for further amyloidosis screening solely due to changes in the echocardiographic IVS cut-off value. Results 1.007 echocardiographic reports were analysed. Of these, 900 included a valid IVS value, while 107 (mainly exclusions of pericardial effusion) did not. From IVS ≥15 mm (5.4%), to ≥14 mm (10.0%), to ≥13 mm (18.6%), to ≥12 mm (32.0%) an increase in patient number was recorded (Figure 1). With regard to CA diagnosis, it can be assumed that systematic screening of patients with IVS ≥12 mm will certainly result in increasing sensitivity but in turn decreasing specificity. On the basis of the patient number within each IVS category we conclude that amyloidosis screening of patients with an IVS ≥13 mm is feasible and reasonable. Conclusion We herein conclude that an IVS ≥13 mm should result in targeted amyloidosis screening. In case of IVS <13 mm the use of further red flags is recommended to avoid unnecessary amyloidosis screening and disproportionate increase in costs.