HCM and the renal function
Several previous studies examined the association between HCM and the incidence of CKD including end stage renal disease (ESRD). From the Korean nationwide population-based cohort study8, the presence of HCM was associated with approximately a 7-fold increased risk of newly diagnosed ESRD. Huang et al.9 reported that approximately 15% of the HCM patients complicated with CKD whose eGFR was <60 mL/min/1.73 m2 and HCM patients with CKD had an increased risk of all-cause mortality. In the present study, the prevalence of an eGFR<60 mL/min/1.73 m2 at baseline in the two groups was 56-67%, which was higher than that in the above previous report9. In HCM patients, the renal dysfunction may be attributed to impaired LV diastolic dysfunction caused by LV hypertrophy and stiffness, which are pathological features of HCM. A reduced LV diastolic function and cardiac output leads to an increased LV filling pressure and renal venous pressure, which eventually attenuates the renal function. As there are few solutions for preventing the progression of LV diastolic dysfunction in patients with HCM, the risk of developing CKD in this patient population is a crucial problem. AF is the most common arrhythmia in patients with HCM,3,15 in whom the incidence is reported to be 20% in their lifetime2. The loss of the atrial kick and irregular beats due to AF reduce the stroke volume and cardiac output16. Several studies have indicated the influence of CKD on the increased risk of AF,17,18 and its mechanism is assumed to be persistent inflammation related to CKD19 and mechanical stress caused by a high atrial pressure due to hypertension and/or heart failure associated with CKD20. The high prevalence of CKD in the HCM patients of the present study indicated that the coexistence of AF accelerates the deterioration in the renal function in patients with HCM, and therefore, maintenance of sinus rhythm in patients with HCM is highly desired.