Atrial Fibrillation Therapy in Refractory Heart Failure

Age	Gender	Occupation	Working Diagnosis
65 Years	Male	Office Worker	Hypokinetic Dilated Cardiomyopathy with Permanent Atrial Fibrillation and Severe Mitral Valve Regurgitation

History

A 65-year-old man, affected by permanent atrial fibrillation for more than 10 years experienced worsening mitral valve regurgitation and maladaptive left ventricle remodeling. These conditions led to hypokinetic dilated cardiomyopathy with severe reduction of left ventricular systolic function and repeated hospitalizations for acute heart failure (American College of Cardiology [ACC] and American Heart Association [AHA] stage C heart failure).

The patient was initially treated with drugs for heart failure, associated with a rate control strategy for atrial fibrillation with a combination of beta blockers and digoxin (carvedilol 6.25 mg twice daily; no further titration was possible because of low ventricular rate at rest and low blood pressure). A baseline electrocardiogram (ECG) showed atrial fibrillation with incomplete left bundle branch block (LBBB) and mean heart rate of 78 bpm.

He was subsequently evaluated for surgical treatment of mitral valve incompetence, which was graded as severe (angiographic grade 4+/4+, vena contracta of 0.76 cm, and regurgitant orifice area of 0.44 cm ² ). The surgeon did not think surgery was the appropriate first-step therapy in this patient, with an unacceptable level of risk because of severe left ventricular dysfunction and dilation (end-diastolic diameter 70 mm, end-diastolic volume 240 mL, ejection fraction 27%).

Coronary angiography documented the absence of significant coronary stenoses.

Considering left ventricular dysfunction, LBBB, and the persistence of heart failure symptoms, notwithstanding optimized medical therapy (New York Heart Association [NYHA] class III), cardiac resynchronization therapy (CRT) was initiated. On November 2008 a biventricular CRT defibrillator (CRT-D) was implanted and beta blocker dosages were increased.

Six months after discharge the patient reported substantial improvement of symptoms (NYHA II), but experienced two inappropriate implantable cardioverter-defibrillator (ICD) shocks because of a high ventricular rate during atrial fibrillation. ICD control documented suboptimal biventricular pacing percentage during atrial fibrillation (<85%, including fusion and pseudofusion beats). Echocardiography documented a favorable remodeling of the left ventricle (LVEF 27% to 38%, end-diastolic diameter 70 to 64 mm, end-diastolic volume 240 to >200 mL, and severe to mild-moderate mitral regurgitation).

The patient underwent atrioventricular node ablation in March 2009. Six months after atrioventricular node ablation (and 1 year after CRT implantation) complete left ventricular reverse remodeling was observed (i.e., LV end diastolic volume 140 mL, LVEF 60%, mild mitral regurgitation); the patient became completely asymptomatic.

However, during subsequent follow-up, the patient showed an extremely difficult control of the international normalized ratio (INR) therapeutic range, with frequent evidence of values above and below the therapeutic range, and had two episodes of corneal hemorrhage. For these reasons, he underwent left atrial appendage occlusion in November 2010.

In March 2011 optimal left atrial appendage occluder positioning was confirmed by cardiac computed tomography and transesophageal echocardiography and oral anticoagulation was safely discontinued.

Comments

Before CRT, titration of beta-blocker therapy was not possible because of a low ventricular rate at rest and low blood pressure. After CRT-D implantation, beta-blocker therapy was optimized, but it was insufficient to warrant complete biventricular pacing (<85%), and two inappropriate ICD shocks on fast atrial fibrillation were observed. Clinical and instrumental benefit was consistent but incomplete.

After successful atrioventricular nodal ablation, 100% effective biventricular pacing was acheived and extremely favorable left ventricular remodeling was then obtained (normal diameters, normal LVEF, and mild mitral valve regurgitation). The patient became asymptomatic.

Current Medications

The patient was taking carvedilol 25 mg twice daily, ramipril 5 mg twice daily, furosemide 12.5 mg daily, spironolactone 25 mg daily, warfarin to maintain INR of 2-3 but subsequently discontinued, and aspirin.

Comments

Optimized medical therapy for heart failure was not discontinued even after complete reverse remodeling of the left ventricle. Oral anticoagulant therapy with warfarin was managed with difficulty by the patient and provoked complications such as corneal hemorrhage. The patient then underwent successful left atrial appendage occlusion.

Current Symptoms

The patient was substantially asymptomatic, with dyspnea only with strenuous exertion (NYHA I).

Physical Examination

BP/HR: 125/80 mm Hg/55 bpm
Height/weight: 175 cm/73 kg
Neck veins: No jugular venous distention
Lungs/chest: Normal breathing sounds, no congestion signs
Heart: Rhythmic cardiac sounds, 1/6 systolic murmur
Abdomen: Normal
Extremities: Warm

Comments

After extremely favorable reverse remodeling, the patient was asymptomatic with good tolerance to physical activity and dyspnea only after strenuous exertion.

Laboratory Data

Hemoglobin: 12.9 mg/dL
Hematocrit/packed cell volume: 38.3%
Mean corpuscular volume: 92.9 fL
Platelet count: 218 × 10 ³ /µL
Sodium: 138 mmol/L
Potassium: 3.6 mmol/L
Creatinine: 0.72 mg/dL
Blood urea nitrogen: 13.5 mg/dL

Electrocardiogram

Findings

The electrocardiogram showed atrial fibrillation, heart rate of 75 bpm, and incomplete LBBB ( Figure 28-1 ). Figure 28-2 shows atrial fibrillation, biventricular pacing, fusion, and pseudofusion beats, and Figure 28-3 shows atrial fibrillation, biventricular pacing, and heart rate of 70 bpm.