Advanced Biventricular Pacemakers to all patients with AV-block?

Sep 5 2006

World Congress of Cardiology Report - Pacemaker treatment for bradycardia is frequently used with more than 500,000 people worldwide receiving a cardiac pacemaker each year.

Electrical conduction disturbance between the atrium and the ventricle (AV-block) is the single most common cause of implanting a pacemaker.

Experimental and clinical studies have indicated that conventional single site right ventricular pacing can be harmful to some patients, compromising the heart pump function and increasing the risk of heart failure.

Patients with complete AV-block have to be paced in the ventricle most of the time.

A new type of pacemaker has been developed to treat patients with congestive heart failure and without AV-conduction disturbance. Pacemaker leads are implanted both in the right ventricle and transvenously in the lateral wall of the left ventricle. Patients are therefore not only paced from the right ventricle but are paced from both ventricles at the same time (biventricular pacing). Patients eligible for biventricular pacing at present time have severe heart failure symptoms and a poor pump function. A randomized trial has shown improvement in heart failure symptoms and reduced mortality during biventricular pacing in these patients (CARE-HF).

We aimed to investigate if biventricular pacemakers implanted in consecutive patients with complete AV-block and normal pump function can prevent the unwanted influence of single site right ventricular pacing.

Thirty patients were randomized equally to achieve either conventional single site right ventricular pacing or biventricular pacing. Patients were followed in the out patient clinic for twelve months and evaluated with high- technology echocardiographic methods.

Three dimensional echocardiographic reconstruction of the left ventricle was used to measure left ventricular pump function and sophisticated tissue-Doppler modalities were used to evaluate left ventricular dyssynchrony during pacing.

We found that biventricular pacing preserved left ventricular pump function and minimized left ventricular dyssynchrony as compared to conventional pacemaker treatment. Left ventricular pump function decreased significantly and left ventricular dyssynchrony was more pronounced in the conventional group during twelve months of pacing.

In conclusion, the present study is the first to show that implantation of biventricular pacemakers in patients with complete AV-block and no heart failure preserves left ventricular pump function and reduces left ventricular dyssynchrony as compared to conventional pacing.

Future perspectives: Patients with AV-block and no heart failure who has to be paced in their ventricle might benefit from a biventricular pacemaker. The result of the present study support further evaluation of biventricular pacing in sub-groups of patients with AV-block most likely to benefit from the treatment e.g. patients with compromised pump function. Future large scale trials should focus on relevant clinical endpoints.

http://www.worldcardio2006.org