Long-term prognosis in patients with bifascicular block--the predictive value of noninvasive and invasive assessment

Prognosis and Natural History of Conduction System Disease in Patients Undergoing Coronary Angiography

BACKGROUND

Infranodal conduction abnormalities, including right or left bundle branch block bifascicular block, and nonspecific intraventricular conduction block are common electrocardiogram (ECG) abnormalities with uncertain persistence and prognostic significance. We evaluated their trajectory and prognostic significance in patients undergoing coronary angiography.

METHODS

We linked an institutional ECG repository with the provincial coronary angiography registry and administrative databases. We included patients without severe left ventricular dysfunction who had an ECG within 180 days of angiography. Multivariable Cox models were used to assess associations between conduction abnormalities and a composite outcome, including all-cause mortality, heart failure hospitalizations, placement of a permanent pacemaker, and placement of an implantable cardiac defibrillator or cardiac resynchronization therapy defibrillator. Serial ECGs were used to model conduction disease as a time-dependent repeated measure.

RESULTS

We included 10,786 patients (mean age, 62.3 ± 12.4 years; 70.3% were male), of whom 2530 (23.4%) had baseline conduction abnormality. During a median follow-up of 3.5 years, conduction normalized in 885 patients (34.9%) and the composite outcome occurred in 1541 patients (14.3%). After multivariable adjustment, intraventricular conduction block (adjusted hazard ratio, 1.42; P = 0.001) and bifascicular block (adjusted hazard ratio, 1.59; P = 0.003) were associated with increased risk of the composite outcome. Left bundle branch block was not associated with the composite outcome.

CONCLUSIONS

Regression of conduction abnormalities was frequent among patients undergoing coronary angiography, primarily for suspected acute coronary syndrome. After adjustment for important confounders including extent of coronary artery disease, infranodal conduction abnormalities were associated with a modest increase in cardiovascular risk.

Prevention of Syncope Through Permanent Cardiac Pacing in Patients With Bifascicular Block and Syncope of Unexplained Origin

Background—

Syncope in patients with bifascicular block (BFB) is a common event whose causes might be difficult to assess.

Methods and Results—

Prevention of syncope through permanent cardiac pacing in patients with bifascicular block (PRESS) is a multicenter, prospective, randomized, single-blinded study designed to demonstrate a reduction in symptomatic events in patients with bifascicular block and syncope of undetermined origin implanted with permanent pacemaker. Device programming mode (NASPE/BPEG code) at DDD with a lower rate of 60 ppm is compared with backup pacing at DDI with a lower rate of 30 ppm. The end point consisted of (1) syncope, (2) symptomatic presyncopal episodes associated with a device intervention (ventricular pacing), and (3) symptomatic episodes associated with intermittent or permanent atrioventricular block (any degree). One hundred one patients were enrolled and randomized. Primary end point events at 2 years were observed in 23 patients, with a significant lower incidence in the study group (hazard ratio, 0.32; 95% confidence interval [CI], 0.10–0.96; P =0.042). Reduction of any symptoms, associated or not with device intervention, was superior in DDD60 compared with DDI30 (hazard ratio, 0.4; 95% confidence interval, 0.25–0.78; P =0.0053). Fourteen patients developed other rhythm diseases and met class I indication for pacing. The annual incidence of rhythm disease development was 7.4%.

Conclusions—

In patients with bifascicular block and syncope of undetermined origin, the use of a dual chamber pacemaker programmed to DDD60 led to a significant reduction of syncope or symptomatic events associated with a cardioinhibitory origin, compared with DDI30 programming. Symptoms associated with a new onset of rhythm disease were found in 15% of the population at 2 years.