Deleterious effect of right ventricular pacing in patients with cardiac transthyretin amyloidosis: potential clinical benefit of cardiac resynchronization therapy

BACKGROUND: Cardiac amyloidosis involvement is associated with a detrimental outcome including frequent arrhythmias, heart failure, and conduction disturbances which may need permanent pacing. CASES SUMMARY: We report two cases of patients with transthyretin amyloidosis (ATTR) who developed heart failure and depressed left ventricular ejection fraction (LVEF) following permanent right ventricular (RV) pacing but highly responded to cardiac resynchronization therapy (CRT). DISCUSSION: The impact of RV pacing and CRT in cardiac amyloidosis is not known. In our cases, the detrimental effect of permanent RV pacing on left ventricular (LV) systolic function and heart failure symptoms was suggested by both permanent RV pacing mediated functional and LV function decline and LV systolic dysfunction reversal following CRT along with QRS width reduction. Whether cardiac resynchronization should be readily recommended in ATTR patients who need ventricular pacing whatever the LVEF deserves further investigation.