The Birmingham Trial of permanent pacing in patients with intraventricular conduction disorders after acute myocardial infarction

Bundle-branch block in middle-aged men: risk of complications and death over 28 years

AIMS

To investigate the long-term fate of men with bundle-branch block (BBB) from a general population sample.

METHODS AND RESULTS

Data were derived from 7392 men without a history of myocardial infarction or stroke, born between 1915 and 1925 and investigated between 1970 and 1973. All participants were followed from the date of their baseline examination until 1998. We identified 70 men with right-BBB and 46 men with left-BBB at baseline. In men with right-BBB, there was no increased risk of myocardial infarction, coronary death, heart failure, or all-cause mortality during follow-up. The multiple-adjusted hazard ratio for progression to high-degree atrioventricular block was 3.64 (99% confidence interval 0.79-16.72). In men with left-BBB, the hazard ratio for high-degree atrioventricular block was 12.89 (4.13-40.24). However, hazard ratio for all-cause mortality was 1.85 (1.15-2.97) when compared with men without BBB, mostly due to outside hospital coronary deaths, whose hazard ratio was 4.22 (1.90-9.34).

CONCLUSION

The presence of BBB was strongly associated with future high-degree atrioventricular block that was more pronounced for left-BBB. Men with left-BBB have a substantially increased risk of coronary death, mainly due to sudden death outside the hospital setting.

The role of permanent pacing after anterior myocardial infarction complicated by transient complete atrioventricular block

A randomised study was performed to assess the influence of prophylactic permanent pacing on the incidence of late sudden death in patients surviving transient complete atrioventricular block with acute anterior myocardial infarction. Fourteen patients were studied, of whom ten died within two years, confirming the high overall late mortality in this group. The deaths included eight of the nine paced patients, of whom seven died suddenly. We conclude that prophylactic permanent pacing is not warranted in patients surviving transient complete atrioventricular block with acute anterior myocardial infarction.

Programmed stimulation after anterior myocardial infarction complicated by bundle branch block--late ventricular tachyarrhythmias and outcome

One hundred and thirty consecutive patients with anterior myocardial infarction complicated by bundle branch block were retrospectively analyzed. Sixty died within 1 week of infarction. Of the remaining 70 patients, 36 had electrophysiology study with programmed stimulation 8-90 (mean 20) days after infarction. Of these, nine patients (35%) who clinically had not manifested either ventricular tachycardia or ventricular fibrillation more than 72 hours after infarction, had inducible ventricular tachycardia which was sustained more than 30 seconds in eight patients. By contrast, assessment of atrioventricular conduction added little to clinical management, long-term follow-up, extending up to 127 months, was available both in those patients whose therapy was directed by electrophysiology study, and was assessed among the other 34 patients who survived at least 7 days after myocardial infarction, but who did not undergo electrophysiology study. While the overall mortality was 55%, the majority of deaths (22/35) occurred within 4 months of infarction and many long-term survivors enjoy a gratifying quality of life. Although programmed stimulation in survivors of anterior myocardial infarction complicated by bundle branch block may identify a high risk subgroup, a prospective randomized trial is required to define the utility of more aggressive stimulation protocols following NASPE recommendations, to identify subgroups of patients in whom newer therapeutic interventions, including antiarrhythmic agents, electrical devices and surgery may be indicated.

Long-term prognostic significance and electrophysiological evolution of intraventricular conduction disturbances complicating acute myocardial infarction

Fifty-nine patients with post-infarctional, isolated intraventricular conduction disturbances (IVCD) who survived the acute stage of myocardial infarction were followed up after hospital discharge for a mean period of 11.4 +/- 4.8 months. Fourteen patients (24%) had HV interval prolongation (greater than 55 ms) during AMI (group A), and 45 patients had normal HV intervals (76%, group B). His bundle recordings were repeated during follow-up in 48 survivors after a mean period of 7.2 +/- 0.7 months. Infranodal conduction delay in the acute stage of infarction was correlated with a higher incidence of heart failure during AMI (78% of patients in group A vs 22% in group B, p less than 0.001), and with higher rate of cardiac mortality during follow-up (50% in group A vs 13% in group B, p less than 0.01). Survivors of group A showed a higher functional NYHA class, a higher incidence of CHF, and a higher prevalence of complex ventricular arrhythmias at Holter monitoring. No statistically significant difference in late sudden death was evident between the two groups of patients, and the global incidence of late AV block was 2%. At repeat His bundle recording no significant change (greater than 5 ms) in HV interval could be demonstrated in comparison to the acute phase recording, neither in patients with prolonged nor in patients with normal HV time. We conclude that HV prolongation in patients with isolated, post-infarctional IVCD is correlated with a worse prognosis, both during acute infarction and during the follow-up period, which presumably reflects wider anatomic damage in comparison to patients with normal HV time. The low incidence of late AV block and the electrophysiological demonstration of the stability of infranodal conduction several months after AMI indicate that these patients do not require permanent prophylactic pacing after acute myocardial infarction.