20. Novel Wireless Technologies for Endocardial Cardiac Resynchronization Therapy

A 68-year-old man previously underwent implantation of a cardiac resynchronization therapy defibrillator (CRT-D) device (February 2007) after a class I indication for CRT at the time—symptomatic drug-refractory ischemic-based heart failure disease, New York Heart Association (NYHA) class III, severe left ventricular dysfunction, and left bundle branch block (LBBB) ventricular conduction delay, with a 130-msec duration QRS complex. Despite CRT, clinical follow-up of the patient was characterized by gradually worsening heart failure progression with further reduction of left ventricular function (left ventricular ejection fraction [LVEF] <20%), dilation of the left ventricle, and, as a result of dilation of the mitral annulus, progression of mitral regurgitation to grade III. Therefore the patient underwent successful positioning of a MitraClip (Abbott Vascular, Abbott Park, Ill.) device in September 2009, thus achieving mitral regurgitation reduction to grade I or II. Paroxysmal atrial fibrillation gradually progressed to become permanent, and ablation of the atrioventricular node was performed to achieve adequate CRT delivery. Other comorbidities included chronic renal insufficiency (reduced glomerular filtration rate of 40 to 50 mL/min/1.73 m²), previous nephrectomy for renal papillary carcinoma, and hyperuricemia.

At presentation, the patient’s therapeutic scheme included maximally tolerated dosages of beta blocker, an angiotensin-converting enzyme [ACE] inhibitor, and other relevant drugs: clopidogrel 75 mg daily, acenodecumerol 1 mg to maintain international normalized ratio between 2 and 3, carvedilol 12.5 mg daily, enalapril 40 mg daily, spironolactone 25 mg daily, atorvastatin 40 mg daily, and aspirin 100 mg daily.

The patient exhibited breathlessness at mild exertion and had NYHA class III to IV heart disease.