Cardiac arrest as an age-dependent prognosticator for long-term mortality after acute myocardial infarction: the potential impact of infarction size.

BACKGROUND:

The development of cardiac arrhythmias resulting in cardiac arrest represents a severe complication in patients with acute myocardial infarction. While the worsening of the prognosis in this vulnerable patient collective is well known, less attention has been paid to its age-specific relevance from a long-term perspective.

METHODS:

Based on a clinical acute myocardial infarction registry we analysed 832 patients with acute myocardial infarction within the current analysis. Patients were stratified into equal groups ( n=208 per group) according to age in less than 45 years, 45-64 years, 65-84 years and 85 years and older via propensity score matching. Multivariate Cox regression analysis was used to assess the age-dependent influence of cardiac arrest on mortality.

RESULTS:

The total number of cardiac arrests differed significantly between age groups, demonstrating the highest incidence in the youngest population with 18.8% ( n=39), and a significantly lower incidence by increasing age (-11.6%; P=0.01). After a mean follow-up time of 8 years, a total of 264 patients (31.7%) died due to cardiovascular causes. While cardiac arrest was a strong and independent predictor for mortality within the total study population with an adjusted hazard ratio of 3.21 (95% confidence interval 2.23-4.61; P<0.001), there was no significant association with mortality independently in very young patients (<45 years; adjusted hazard ratio of 1.73, 95% confidence interval 0.55-5.53; P=0.35).

CONCLUSION:

We found that arrhythmias resulting in cardiac arrest are more common in very young acute myocardial infarction patients (<45 years) compared to their older counterparts, and were able to demonstrate that the prognostic value of cardiac arrest on long-term mortality in patients with acute myocardial infarction is clearly age dependent.