Cardiac transthyretin amyloidosis in patients with conduction system disease

Abstract Introduction Cardiac amyloidosis (CA) is characterized by extracellular deposition of misfolded proteins in the heart. Most cardiac amyloidosis result from fibrils consisting of monoclonal immunoglobulin light chains (AL) or transthyretin (ATTR). Conduction abnormalities that may occur years before heart failure are commonly encountered among patients with CA. These abnormalities constitute an important cause of morbidity and mortality, often leading to the need of pacemaker implantation. Purpose As unexplained LV wall thickness ≥ 12 mm is a screening sign of possible cardiac amyloidosis. We hypothesized that systematic screening for CA in patients requiring permanent pacemakers with unexplained LV wall thickness of ≥ 12 mm might be useful and lead to early diagnosis of this condition. To the best of our knowledge, the usefulness of such screening has not been investigated before. This project, therefore, aimed to determine the prevalence of ATTR and AL amyloidosis in this preselected group, and to propose the most suitable battery of diagnostic procedures for this purpose. Methods Population to be tested: Consecutive patients ≥50 years referred for permanent pacemaker implantation with unexplained echocardiography-confirmed LV wall thickness ≥12 mm. The research protocol was that of an open-label prospective study. In a subgroup of these patients, full echocardiography parameters were recorded and biochemistry analysis including serum troponin I and NT-proBNP was performed before pacemaker implantation. Data from this subgroup was subsequently used for further analyses. All patients were screened for ATTR-CA according to the recommendations of the Position statement of the ESC Working group on myocardial and pericardial diseases. Tc-DPD scintigraphy scan served as a gold standard for determining the diagnosis of cardiac ATTR. Results Out of 180 consecutive patients meeting inclusion criteria, 15 % (27 patients) suffered from amyloidosis (22 patients were diagnosed with ATTR and 5 with AL cardiac amyloidosis). Full data were recorded in 110 patients, results from this subgroup are detailed in Table 1 and Figure 1, showing multiple parameters to be associated with cardiac amyloidosis. Figure 1 then depicts the distributions of the aforementioned parameters with the highest differences between individuals with and without amyloidosis. Conclusions The prevalence of cardiac amyloidosis in the investigated group was 15 %. Systematic screening for ATTR in patients with unexplained LV wall thickness ≥ 12 mm requiring permanent pacemaker implantation seems rational and could possibly lead to an earlier diagnosis of cardiac amyloidosis, especially ATTR. Our results suggest a possibility of employing these parameters to develop a scoring system for the detection of cardiac amyloidosis, which we aim to do within the scope of our ongoing research.Table 1 Figure 1