Author + information
- Zhao Lei,
- Zhuang Tian and
- Quan Fang
For light-chain amyloidosis (AL) patients with suspected cardiac involvement, echocardiography is an essential screening modality, with a presentation of an increased interventricular septal (IVS) thickness as a diagnostic criterion. However, patients with cardiac amyloidosis could have normal IVS thickness, a contradiction to its infiltrative nature. Therefore, we aimed to describe patients with cardiac AL amyloidosis and normal IVS thickness and evaluated the effect of IVS on the overall survival.
A total of 107 patients with a first cardiac AL amyloidosis diagnosis were retrospectively reviewed between January 2010 and January 2015. Patients were categorized into two groups according to the diastolic IVS thickness.
In the entire cohort, 24 patients (22.4%) presented increased IVS thickness, 62.6% were male, mean age was 55 (46, 63) years old and 57.9% were accompanied with severe heart failure. In the group with increased IVS thickness the heart rate was faster (84 vs. 79, p=0.02), along with a higher prevelance of pseudoinfarction and intraventricular conduction delays (p=0.004, p=0.036, respectively). Low-voltage electrocardiography was more common in patients with normal IVS thickness (70.8% vs. 44.6%, p=0.023). There were no significant differences on other echocardiographic characteristics between two groups except for diastolic IVS and left ventricular posterior wall thickness. Six patients with normal IVS thickness showed late gadolinium enhancement (LGE) pattern in cardiac magnetic resonance imaging, among which, four patients presented global transmural and/or subendocardial LGE pattern and two had patchy LGE pattern. During a median follow-up period of 39 (26, 52) months, a total of 80 patients died. The Kaplan-Meier analysis demonstrated that the survival rate for patients with normal IVS thickness was not significantly different from that of those with hypertrophic phenotype. But in the subgroup without severe heart failure, survival of patients with normal IVS thickness was relatively shorter (median 13 months vs. 24 months, p=0.011). In the multivariate Cox proportional model, advanced NYHA, E/A ratio and pseudoinfarction were independently predictors of survival.
In cardiac amyloidosis, IVS thickness was not always increased to more than 12mm. The diagnosis of this disease should not only focus on the hypertrophic phenotype, but also refer to other sensitive modalities. A preliminary suspicion for cardiac amyloidosis, with a systematic approach to evaluation would ensure an accurate diagnosis of this uncommon presentation of infiltrative disorder.