Abstract Background
Atrial fibrillation (AF) impacts prognosis of hypertrophic cardiomyopathy (HCM) by promoting progressive heart failure (HF) and increasing risk of stroke.
Over the past years, several indexes and methods to predict AF among HCM patients have been proposed. However, they are limited by a lack of accuracy.
Aims of our study was to evaluate the role of new echocardiographic parameters in predicting new onset of AF and to validate them by cardiac magnetic resonance (CMR).
Methods and Results
We analyzed clinical and imaging data of 141 HCM patients in sinus rhythm who underwent first evaluation at our center (51.2 ± 17.3 years, mean follow up 5.3 ± 3 years). Main parameters analyzed were left atrium (LA) end-diastolic volume (LAV min), end-systolic volume (LAVmax), LA ejection fraction (LAEF), left atrioventricular coupling index (LACI), and LA diameter (LAD). LACI was defined by the LAVmin divided by the LV end-diastolic volume (LVEDV); this parameter was assessed in previous studies as a good detector of early atrial remodeling and impaired LV compliance.
35 patients developed new-onset AF (after a mean period of 4 ± 3.2 years). At the baseline evaluation, LACI, LAD, and LAVmin showed to be significantly greater in patients who developed AF compared to patients who did not. At CMR, LACI >44% accurately predicted new-onset AF (sensitivity 85%, specificity 70%; AUC 0.81). LACI by ETT showed similar accuracy (AUC 0.75) and was superior to that shown by LAD (AUC 0.71) (Figure 1).
Patients who did not develop AF had significantly higher LAEF at ETT (49.3 ± 11% vs 37 ± 9.6%; p < 0.0001). CMR analysis confirmed this result. LAEF >43% was a good predictor of AF free survival (log rank<0.001). Conversely, at a multivariate analysis, LAFE <43% by ETT was independently associated with AF occurrence (OR 4.5, 95% CI 1.4-13.7) (Figure 2).
11 patients experienced death or heart transplant (HTx). Higher values of LACI and LAVmin and lower values of LAEF were found to be associated the composite outcome of death or HTx. LACI>60% predicted the composite of death or HTx with good accuracy (AUC 0.74) (Figure 3).
Conclusions
LACI and LAEF showed to improve accuracy in predicting the new onset of AF in HCM patients without severe LA dilatation (LAD>45mm). Higher LACI and Lower LAEF (namely <43%) identify patients at higher risk of new onset AF, and, therefore, worthy of a more strict follow-up.
