A 56 year-year-old male was referred to you with progressive easy fatigueability, moderate exertional dyspnea and two pillow orthopnea of a 1 year duration.

   Relevant physical findings include BP 104/64 mm Hg, pulse 104/min and unlabored repirations at 20/min. Neck veins are engorged 3 cm above the clavicle at 30 degrees and the abdomino-jugular (also referred to as hepato-jugular) reflux is positive. The apical impulse is located two cm lateral to the left mid-clavicular line in the 6th interspace. Soft S3 and S4 gallops together with a grade 2/6 holosytolic murmur are heard at the apex. There are bibasilar inspiratory rales and 2+ pitting edema of the legs.

   Chest x-ray reveals moderate cardiomegaly with pulmonary congestion. EKG shows a sinus mechanism with a CLBBB and frequent unifocal premature ventricular contractions. Echocardiography reveals a left ventricular end-diastolic dimension of 62 mm with global hypokinesia, EF of 38% and moderate MR. The inferior vena cava is moderately distended and demonstrates poor inspiratory collapse

Which ONE of the following is initially indicated in the management of this patient?