AIMS: This study aimed to evaluate the change of the main electrocardiographic (ECG) characteristics and their prognostic role across the main subtypes of cardiac amyloidosis [light-chain amyloidosis (AL) and hereditary (ATTRv) and wild-type transthyretin amyloidosis (ATTRwt)]. METHODS AND RESULTS: This multicentre, retrospective study was performed in six referral centres for cardiac amyloidosis. Clinical and ECG data were collected at the first and last evaluations. Three hundred fifty-six patients were included (AL, n = 105
ATTRv, n = 50
ATTRwt, n = 201). The median age was 76 (67-81) years, and 271 (74%) were men. At baseline, patients with ATTRwt showed a higher prevalence of conduction abnormalities compared with those with AL [first-degree atrioventricular block, n = 51 (40%) vs. n = 13 (34%), P <
0.01
left bundle branch block, n = 23 (11%) vs. n = 2 (2%), P <
0.01], and patients with AL more often had low QRS voltage [n = 58 (55%)
in ATTRv, n = 17 (34%)
in ATTRwt, n = 67 (33%), P value <
0.01] and T wave inversion compared with those with ATTR [n = 39 (37%)
in ATTRv, n = 9 (18%)
in ATTRwt, n = 37 (18%)]. After a median follow-up of 15 (8-26) months, the adjusted differences in mean PR, QRS interval, total, peripheral, and precordial QRS scores were similar across subtypes of amyloidosis (P value for linear regression >
0.05). The adjusted odds ratios for the development of right bundle branch block were higher in AL compared with ATTRwt [odds ratio 4.7 (95% confidence interval 1.5-15), P <
0.05]. QRS duration at baseline remained independently associated with patient survival in the overall population even after adjustment for relevant clinical variables [hazard ratio 1.78 (95% confidence interval 1.13-2.8), P <
0.01]. CONCLUSIONS: The progression of the ECG abnormalities seems similar across amyloidosis subtypes. QRS duration could be a marker of more advanced disease.