Abstract
ObjectivesTo evaluate the impact of autoantibodies against the M2-muscarinic receptor (anti-M2-R) on the clinical outcomes of patients receiving the standard treatment for peripartum cardiomyopathy (PPCM).MethodsA total of 107 PPCM patients who received standard heart failure (HF) treatment between January 1998 and June 2020 were enrolled in this study. According to anti-M2-R reactivity, they were classified into negative (n = 59) and positive (n = 48) groups, denoted as the anti-M2-R (−) and anti-M2-R (+) groups. Echocardiography, 6-min walk distance, serum digoxin concentration (SDC), and routine laboratory tests were performed regularly for 2 years. The all-cause mortality, cardiovascular mortality, and rehospitalisation rate for HF were compared between the two groups.ResultsA total of 103 patients were included in the final data analysis, with 46 in the anti-M2-R (+) group and 57 in the anti-M2-R (−) group. Heart rate was lower in the anti-M2-R (+) group than in the anti-M2-R (−) group at the baseline (102.7 ± 6.1 bpm vs. 96.0 ± 6.4 bpm, p < 0.001). The initial SDC was higher in the anti-M2-R (+) group than in the anti-M2-R (−) group with the same dosage of digoxin (1.25 ± 0.45 vs. 0.78 ± 0.24 ng/mL, p < 0.001). The dosages of metoprolol and digoxin were higher in the anti-M2-R (−) patients than in the anti-M2-R (+) patients (38.8 ± 4.6 mg b.i.d. vs. 27.8 ± 5.3 mg b.i.d., p < 0.0001, respectively, for metoprolol; 0.12 ± 0.02 mg/day vs. 0.08 ± 0.04 mg/day, p < 0.0001, respectively, for digoxin). Furthermore, there was a greater improvement in cardiac function in the anti-M2-R (−) patients than in the anti-M2-R (+) patients. Multivariate analysis identified negativity for anti-M2-R as the independent predictor for the improvement of cardiac function. Rehospitalisation for HF was lower in the anti-M2-R (−) group, but all-cause mortality and cardiovascular mortality were the same.ConclusionsThere were no differences in all-cause mortality or cardiovascular mortality between the two groups. Rehospitalisation rate for HF decreased in the anti-M2-R (−) group. This difference may be related to the regulation of the autonomic nervous system by anti-M2-R.
Highlights
Peripartum cardiomyopathy (PPCM) is a rare idiopathic dilated cardiomyopathy defined by the signs and symptoms of heart failure (HF) in the last month of pregnancy through the fifth month postpartum [1]
There were no differences in all-cause mortality or cardiovascular mortality between the two groups
Rehospitalisation rate for HF decreased in the anti-M2-R (−) group
Summary
Peripartum cardiomyopathy (PPCM) is a rare idiopathic dilated cardiomyopathy defined by the signs and symptoms of heart failure (HF) in the last month of pregnancy through the fifth month postpartum [1]. The definition of PPCM requires that there is no previously known structural heart disease, and that echocardiographic parameters achieve left ventricular ejection fraction (LVEF) < 45% and/or fractional shortening < 30%, with a possible additive left ventricular end-diastolic dimension > 2.7 cm/m2 body surface area [2]. This disease is associated with high morbidity and mortality, yet its aetiology remains unknown [1]. Autoantibodies against β1 adrenergic receptors (anti-β1-R) and autoantibodies against M2-muscarinic receptor (anti-M2-R) are more common in patients with PPCM [3]. The clinical significance of these findings is currently unknown
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