History
An 81-year-old patient with type 2 diabetes and hypertension as cardiovascular risk factors sought treatment because of effort-related dyspnea (New York Heart Association [NYHA] class III) and presyncopal episodes. A complete cardiologic assessment was performed. On the baseline electrogram (ECG), atrial fibrillation with incomplete left bundle branch block (LBBB) was found; at transthoracic echocardiography, dilatative cardiomyopathy with reduced left ventricular ejection fraction (LVEF 25%) was the main finding, together with a moderate left atrial dilation (anteroposterior diameter 51 mm) and moderate mitral regurgitation. A 24-hour Holter ECG recording also was performed that evidenced atrial fibrillation with a mean ventricular rate of 90 bpm and no pathologic pauses. Medical therapy was optimized, but in a few months no improvement was observed. The patient therefore received a biventricular implanted cardioverter-defibrillator (ICD) (no atrial lead was implanted because atrial fibrillation was considered permanent).
Six months later, LVEF was slightly improved (30%) and no changes were found in left atrial dimension and mitral regurgitation. Electronic device control also was done, and a suboptimal biventricular pacing percentage was found (82%, Figure 31-1) because of the high rate of atrial fibrillation with spontaneous atrioventricular conduction. No clinical changes were observed. These findings were considered secondary to lack of biventricular full-time pacing, and the patient underwent atrioventricular junction ablation. After 3 months of full-time biventricular stimulation (Figure 31-2), further improvement in LVEF was observed (from 30% to 40%), along with mitral regurgitation and left atrial diameter reduction. The patient reported clinical improvement (no further presyncopal episodes, NYHA class IIB). Surprisingly, at baseline ECG, regular sinus activity was found. The issue was whether to proceed with system upgrade by atrial lead implantation.
Comments
After ICD implantation, only slight instrumental benefit was observed without any clinical improvement. This was due to suboptimal biventricular pacing percentage, because biventricular devices are known to need almost full-time pacing to be effective. We therefore decided to perform atrioventricular node ablation, following which approximately 100% of biventricular pacing was obtained. The positive left ventricular remodeling induced by pacing led to an initial improvement in LVEF and the patient’s symptoms. Improving cardiac contractility and ventricular output, thus reducing filling pressure, may have played an important role in reducing atrial stretching, atrial pressure, and, subsequently, left atrial dimensions, removing one of the principal causes of atrial fibrillation. Moreover, mitral regurgitation was reduced as a result of resynchronization therapy. These may be the reasons why sinus rhythm was restored.
FIGURE 31-1
FIGURE 31-2
Current Medications
The patient was taking carvedilol 9.375 mg twice daily, furosemide 25 mg once daily, warfarin 5 mg based on international normalized ratio values, ramipril 5 mg once daily, digoxin 0.125 mg once daily, and amiodarone 200 mg once daily.
Comments
The patient was taking optimal medical therapy for heart failure; an angiotensin-converting enzyme inhibitor and a beta blocker were not fully titrated because of low blood pressure values. Amiodarone was administered even though atrial fibrillation was thought to be permanent as a rate control drug, because carvedilol and digoxin together were not enough. Of course, warfarin also was administered.
Current Symptoms
The patient was in NYHA class IIB, showing improvement after atrioventricular node ablation. Nevertheless, moderate effort-related dyspnea persisted. Despite advanced age, the patient normally engaged in moderate physical activity.
Comments
Improved cardiac contractility, left ventricular reverse remodeling, and reduced filling pressure provided by biventricular pacing, in the presence of optimal medical therapy and after atrioventricular node ablation, led to a better functional class. However, lack of atrial contractility resulting primarily from atrial fibrillation and then desynchronized atrial and ventricular activities once sinus rhythm was restored may have contributed to symptoms patient still reported.
Physical Examination
Comments
Even in the presence of a desynchronized atrial activity, no signs of congestive heart failure were found, thanks to biventricular pacing–induced improvements. Auscultatory findings related to mitral regurgitation were present.
Laboratory Data
Electrocardiogram
Findings
Figure 31-3 shows the baseline ECG, atrial fibrillation with mean ventricular response of 90 bpm, and incomplete left bundle branch block. Figure 31-4 shows the ECG obtained after ICD implantation, showing biventricular pacing with underlying atrial fibrillation; some spontaneously conducted beats are visible. Figure 31-5 shows ECG obtained after atrioventricular junction ablation. Full-time biventricular pacing with underlying atrial fibrillation can be seen. Figure 31-6 is an ECG showing biventricular pacing with underlying desynchronized sinus rhythm, obtained 3 months after atrioventricular junction ablation. Figure 31-7 shows the ECG performed after atrial lead implantation, showing atrial tracked biventricular pacing.
Comments
The figures show electrocardiographic evolution, from the beginning to the three-lead system.
Chest Radiograph
Findings
Figure 31-8 presents the chest radiograph obtained after atrial lead implantation.
Exercise Testing
The patient’s 6 Minute Walk Test (6MWT) before ICD implantation was 250 m. His 6MWT at the time of atrioventricular node ablation (6 months after implantation) was 270 m. At the time sinus rhythm resumption was discovered (3 months after atrioventricular junction ablation), his 6MWT was 350 m. At 3 months after atrial lead implantation, his 6MWT was 400 m.
Comments
No functional class improvement occurred after biventricular ICD implantation. An improvement was achieved only after atrioventricular node ablation by obtaining 100% biventricular stimulation. Further improvement was obtained after atrial lead implantation.
Echocardiogram
Findings
The echocardiogram obtained before ICD implantation showed a LVEF of 25%, end-diastolic diameter of 65 mm, left atrium diameter of 51 mm, and moderate mitral regurgitation (2+, vena contracta 0.55 cm, and regurgitant orifice area 0.29 cm2).
Comments
Baseline echocardiography, showing reduced left ventricular systolic function. Left atrial and ventricular dilation were also present, leading to secondary mitral regurgitation.
FIGURE 31-9
Findings
The echocardiogram obtained 6 months after ICD implantation revealed a LVEF of 30%, end-diastolic diameter of 62 mm; left atrium diameter of 50 mm; and moderate mitral regurgitation (2+, vena contracta 0.51 cm, and regurgitant orifice area 0.28 cm2).
Comments
Because of insufficient biventricular pacing, only a small instrumental improvement was observed.
Findings
The echocardiogram obtained 3 months after atrioventricular junction ablation showed a LVEF of 40%, end-diastolic diameter of 58 mm, left atrium diameter of 45 mm, and moderate mitral regurgitation (2+, vena contracta 0.37 cm, and regurgitant orifice area 0.24 cm2).
Comments
A few months after atrioventricular node ablation, left atrial and ventricular reverse remodeling led to an improvement of systolic function and a reduction in left atrial and ventricular diameters. Secondary mitral regurgitation decreased thereafter.
Findings
The echocardiogram obtained 6 months after atrial lead implantation (Figure 31-9) showed a LVEF of 50%, end-diastolic diameter of 55 mm, left atrium diameter of 43 mm, and mild mitral regurgitation (1+, vena contracta 0.29 cm, and regurgitant orifice area 0.19 cm2).
Comments
Restoring synchronized atrioventricular activity led to an almost normal LVEF; the left atrium and left ventricle diameters were only slightly higher than normal, and mitral regurgitation also was reduced.
Focused Clinical Questions and Discussion Points
Question
Is biventricular device implantation the right choice in a patient with left ventricular dysfunction and permanent atrial fibrillation (or is it supposed to be)?
Discussion
Most of the studies evaluating the clinical benefits of biventricular pacing have been conducted in patients with sinus rhythm.3 However, most patients with reduced LVEF may present one or more episodes of paroxysmal or persistent atrial fibrillation, which may become permanent, despite pharmacologic treatment, as a result of concomitant left atrial remodeling. Patients with atrial fibrillation are usually older, carry more comorbidities, and may present lower pacing percentages because of spontaneous conduction. Implanting a biventricular device improves myocardial contractility and ventricular output, reduces filling pressures, and reduces possible associated secondary mitral regurgitation, all of which may lead to the stopping of both atrial and ventricular remodeling (and sometimes also reversing it),2 thus reducing the likelihood of developing atrial arrhythmias or increasing their number of atrial arrhythmias. Atrioventricular node ablation should be considered in the presence of suboptimal biventricular pacing percentages. Sinus rhythm resumption is not meant to be the goal; however, it is clear that most patients experience clinical benefits and left atrial and ventricular reverse remodeling by biventricular pacing, thus making it a good choice in this patient population.
Question
Is sinus rhythm resumption predictable in this type of patient?
Discussion
A 2010 study conducted on patients with permanent atrial fibrillation and cardiac resynchronization therapy (CRT) found clinical predictors to be left ventricular end-diastolic diameter less than 65 mm, narrow CRT paced QRS (<150 ms), left atrial diameter less than 50 mm, and atrioventricular junction node ablation.1 In our patient, all four criteria were satisfied, thus making this event quite likely.
Question
Is atrial lead implantation a good choice? Is an actual improvement expected?
Discussion
Once sinus rhythm resumption was found, the patient was in NYHA class IIB with a moderately reduced LVEF (40%). It is reasonable to think that restoring normal atrioventricular synchrony, thus making atria regularly fill ventricles and avoid retrograde flow (which may raise pulmonary pressures) could lead to a further clinical and instrumental improvement.1 Despite advanced age, considering the active lifestyle and usual level of physical activity, the clinical benefit expected by adding a new lead would be worth the risks related to a new invasive procedure.
Final Diagnosis
The final diagnosis in this patient is ischemic dilatative cardiomyopathy with permanent atrial fibrillation, left ventricular function recovery, clinical improvement, and sinus rhythm restoration after atrioventricular junction ablation and full-time biventricular pacing.
Plan of Action
The plan for this patient was right atrial lead implantation to further improve the patient’s symptoms.
Intervention
The intervention performed was right atrial lead implantation.
Outcome
The patient was in NYHA class I. Six months after system upgrade, an almost normalized LVEF 50% was found, together with mild left atrial and ventricular dilation and mild mitral regurgitation.
Comments
Restoring atrioventricular synchrony in the presence of atrial tracked biventricular pacing led to an almost normalized heart function.
Selected References
1. Gasparini M., Steinberg J.S., Arshad A. et al. Resumption of sinus rhythm in patients with heart failure and permanent atrial fibrillation undergoing cardiac resynchronization therapy: a longitudinal observational study. Eur Heart J. 2010;31:976–983.
2. Kies P., Leclercq C., Bleeker G.B. et al. Cardiac resynchronisation therapy in chronic atrial fibrillation: impact on left atrial size and reversal to sinus rhythm. Heart. 2006;92:490–494.
3. Vardas P.E., Auricchio A., Blanc J.J. et al. European Society of Cardiology. Guidelines for cardiac pacing and cardiac resynchronization therapy: The Task Force for Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology. Developed in Collaboration with the European Heart Rhythm Association. Eur Heart J. 2007;28:2256–2295.
