[Complete bundle-branch block and myocardial infarct. Natural history. Comparative study]

Area of Science:

• Cardiology
• Internal Medicine

Background:

• Myocardial infarction (MI) can be complicated by conduction defects.
• Complete branch block (CBB) occurs in a notable percentage of MI cases, particularly with anterior necrosis.

Purpose of the Study:

• To compare the short- and long-term outcomes of MI patients with CBB versus those without conduction defects.
• To evaluate the efficacy of temporary cardiac pacemaking in MI with CBB.
• To assess the need for prophylactic pacemaker implantation in MI complicated by CBB.

Main Methods:

• Retrospective comparison of two groups: 45 MI patients with CBB (Group A) and 45 MI patients without conduction defects (Group B).
• Analysis of immediate mortality, long-term mortality causes (MI recurrence, cardiac failure), and sudden death incidence.
• Assessment of temporary cardiac pacemaking impact on immediate mortality.

Main Results:

• Group A (MI with CBB) exhibited significantly higher immediate mortality, independent of temporary cardiac pacemaking, correlating with myocardial destruction extent.
• Long-term follow-up revealed increased deaths in Group A due to MI recurrence and intractable cardiac failure.
• Sudden death incidence was comparable between Group A (15%) and Group B (13%) without clear electrocardiographic explanation.

Conclusions:

• MI complicated by CBB leads to greater immediate and long-term mortality, primarily from factors other than sudden death.
• Temporary cardiac pacemaking did not alter the high immediate mortality in MI with CBB.
• The study does not support the routine prophylactic implantation of cardiac pacemakers for MI patients with CBB.