Systematic review and meta-analysis evaluates apical sparing ratio for cardiac amyloidosis detection in hypertrophy

PURPOSE: Cardiac amyloidosis (CA) is an underdiagnosed cause of heart failure with overlapping phenotypes, such as aortic stenosis (AS) and hypertrophic cardiomyopathy. The apical sparing ratio (ASR) derived from echocardiographic strain imaging has been widely adopted as a potential screening tool for CA, though performance across clinical contexts remains uncertain. METHODS: We performed a systematic review and meta-analysis of studies evaluating the diagnostic accuracy of ASR for identifying CA among patients with left ventricular hypertrophy (LVH), including a prespecified subgroup of patients with severe AS, in September 2024. Random-effects models incorporating multiple ASR thresholds were used to estimate pooled sensitivity, specificity, and area under the summary receiver operating characteristic curve (AUC). RESULTS: Among 3501 records screened, 22 studies (n = 4144) met inclusion criteria for primary analysis. An optimal Youden ASR of threshold = 0.83 yielded pooled sensitivity (95% confidence interval) of 73% (66%, 79%) and specificity of 77% (67%, 84%), with an AUC of 0.81 (0.69, 0.89). In the severe AS subgroup (5 studies, n = 911), pooled sensitivity and specificity were 65% (47%, 80%) and 74% (58%, 85%), respectively, with an AUC of 0.79 (0.70, 0.92). Across analyses, high heterogeneity was observed. Sensitivity analyses, excluding high-bias or low-threshold studies, produced similar findings. CONCLUSION: ASR demonstrates only modest diagnostic performance for differentiating CA from hypertrophic phenotypes, with limited sensitivity at conventional thresholds. These findings underscore the limitations of ASR as a standalone screening tool and highlight the need for alternative approaches to improve diagnostic accuracy.