Reduced bi-atrial reservoir strain in patients with cardiac amyloidosis: a cardiac magnetic resonance feature-tracking study

Background Although heart strain analysis is useful for diagnosing cardiac amyloidosis (CA), it remains unclear which chamber best distinguishes CA from hypertrophic cardiomyopathy (HCM). This study analyzed strain in all four cardiac chambers in patients with CA and HCM using cardiac magnetic resonance (CMR) feature-tracking. Methods We enrolled 30 patients with left ventricular hypertrophy (15 with CA and 15 with HCM) and 17 healthy volunteers as a reference. Participants underwent 1.5-Tesla CMR to assess volume, function, and strain parameters in both ventricles and atria. The primary analysis comprised four comparisons between CA and HCM, one representative parameter per chamber (bi-ventricular longitudinal strain and bi-atrial reservoir strain), with Bonferroni correction ( P < 0.0125). Additionally, exploratory analyses of the other parameters were conducted comparing patients with CA to HCM. Results Left atrial (LA) and right atrial (RA) reservoir strain were lower in CA than in HCM (LA: 7.1 ± 4.1% vs. 10.3 ± 3.9%, P = 0.035; RA: 10.8 ± 6.9% vs. 22.1 ± 12.9%, P = 0.005), whereas ventricular longitudinal strain did not differ. After Bonferroni correction, only RA reservoir strain remained significant. In an exploratory receiver operating characteristic analysis, the areas under the curve for LA and RA reservoir strain were 0.73 and 0.78, respectively, and did not differ significantly. Conclusion Bi-atrial reservoir strain was lower in CA than in HCM, and the difference in RA reservoir strain remained significant after accounting for multiplicity. Atrial reservoir strain may provide adjunctive, contrast-free functional information to help differentiate CA from HCM.