**3. Method**

#### **3.1. Pacing- and dobutamine- induced MA**

It is more prevalent and likely to be sustained, as exemplified by pacing-induced MA. Right atrial pacing was initiated at 80 beats per minute (bpm) and was increased in increments of 10 bpm. We selected steady-state LV pressure data for at least 2 min at the baseline and at each pacing rate for analysis.[4] We calculated the maximum first derivative of LV pressure (LV *dP/dt*max) as an index of contractility. To evaluate LV isovolumic relaxation, we computed *T*1/2, as previously described.[5] After the hemodynamic values had checked at baseline, dobuta‐ mine was infused intravenously at incremental doses of 5, 10, and 15 µg kg–1min–1 and hemodynamic measurements were performed at the end of each 5-min infusion period. MA was diagnosed if the pressure difference between the strong and weak beats was ≥4 mmHg continuously in the analyzed LV pressure data, as previously described.[6]

We prospectively followed up all patients for the occurrence of primary events, which were defined as cardiac death (from worsening heart failure or sudden death) or the unscheduled readmission for decompensated heart failure. Noncardiac death was excluded.
