Abstract
2295
Introduction: Activation of cardiac fibroblasts plays a key role in the progression of myocardial fibrosis, which is a hallmark of hypertrophic cardiomyopathy (HCM) and contributes to adverse cardiovascular events. This study aimed to explore the imaging characteristics and clinical significance of cardiac fibroblast activation in HCM.
Methods: Forty-four HCM patients (26 men, mean age: 44 ± 14 years) were prospectively recruited. All patients underwent cardiac 18F-labeled fibroblast activation protein inhibitor (FAPI) PET/CT. Myocardial FAPI activity was analyzed on intensity (target-to-background uptake ratio, TBRmax), extent (the percentage of FAPI uptake volume over the left ventricular (LV) volume, FAPI%), and amount (FAPI%×TBRmax). Patients were divided into two groups using the 75th percentile of FAPI amount as the cutoff value. Univariate and multiple logistic regression analyses were used to identify factors related to the higher FAPI amount. Moreover, the relationship between FAPI parameters and the individualized 5-year sudden cardiac death (SCD) risk score of 2014 European Society of Cardiology (ESC) was explored.
Results: All HCM patients had obvious FAPI uptake in the left ventricle. Univariate analysis demonstrated the maximal LV thickness, amount of hypertrophied segments, and resting left ventricular outflow tract (LVOT) gradient ?30 mmHg were related to higher FAPI amount (all p < 0.05). Multiple logistic regression analysis showed the amount of hypertrophied segments was an independent factor predicting higher FAPI amount (OR = 1.461, 95%CI: 1.104~1.932, p = 0.008). Patients with intermediate or high 5-year SCD risk had higher FAPI amount [5.33 (4.02, 7.31) vs. 3.65 (2.30, 4.91), p = 0.025] and volume [0.53 (0.47, 0.73) vs. 0.42 (0.32, 0.53), p = 0.037], and the FAPI amount was positively correlated with the 5-year risk score of 2014 ESC (Spearman r = 0.354, p = 0.018).
Conclusions: This study identifies cardiac fibroblasts activation in HCM patients using 18F-FAPI imaging. The amount of hypertrophied segments is an independent factor in predicting the higher FAPI amount, which is positively correlated with the risk of SCD.