Rationale:

Risk stratification for subsequent cardiovascular events following a myocardial infarction (MI) is an important area of research.

Objectives:

This study investigates the added prognostic value of the endothelial brachial artery flow-mediated dilatation (FMD) in a population of low-risk patients with uncomplicated MI.

Methodology:

One hundred and seventy nine post-MI patients [110male/ 69 female, mean age: 64.8 +/- 10.0 years, ejection fraction: 51.9 +/- 12.2%] were included in this analysis. Ultrasound images of the brachial artery were used to determine FMD and percent change in arterial diameter following reactive hyperemia created by an inflated cuff (50 mmHg above systolic pressure for 5 minutes). Subjects were tracked for subsequent cardiovascular events following data collection.

Results:

There were 45 subsequent cardiovascular events during a mean tracking period of 13.7 (+/-9.5) months. Receiver operating characteristic (ROC) curve analysis revealed a diagnosis of diabetes (ROC area: 0.67, P = 0.001, 95% confidence interval: 0.58-0.77) and percent change in arterial diameter (ROC area: 0.63, P = 0.01, 95% confidence interval: 0.53-0.73, optimal threshold: <=/> 0.045%) had significant prognostic classification schemes. Multivariate Cox regression analysis revealed that while a diagnosis of diabetes was the strongest predictor of subsequent cardiovascular events (chi-square: 12.9, P < 0.001), percent change in arterial diameter added significant predictive value (residual chi-square: 9.2, P = 0.002). Kaplan-Meier analysis revealed the event-free survival rate for subjects without diabetes and an arterial diameter change >0.045%, with diabetes or an arterial diameter change <=0.045%, and with diabetes and an arterial diameter change <=0.045% was 88.7%, 74.4% and 38.5%, respectively (Log-rank: 24.9, P < 0.0001).

Conclusions:

The results of the present study document that assessment of endothelial function improves cardiovascular risk stratification in patients with uncomplicated MI. A relevant implication is that non-invasive evaluation of brachial artery FMD during the pre-discharge phase in post-MI patients may be clinically advantageous.