Occurrence and clinical impact of microembolic signals (MES) in patients with chronic cardiac diseases and atheroaortic plaques--a systematic review.

BACKGROUND

In various cardiac diseases, thrombembolism constitutes a major risk, and in these patients clinically silent microembolic signals (MES) are detectable within the transcranial Doppler frequency spectrum (TCD) of the major brain arteries. MES are already an accepted surrogate parameter of the future risk of stroke in patients with carotid artery stenosis. The aim of this review is to summarize and evaluate the data about occurence and clinical impact of MES in patients with chronic cardiac diseases and to clarify whether cardiogenic MES can serve as a surrogate parameter of the heart's future thrombembolic risk as well.

METHODS

We performed a systematic MEDLINE search and reviewed the currently available literature about chronic cardiac diseases and atheroaortic plaques leading to MES apart from cardiosurgical procedures.

CONCLUSION

The cardiac conditions producing MES are heterogenous and therefore the prevalence of MES is highly variable. The data in patients with acute or after myocardial infarction, endocarditis, patent foramen ovale, mitral valve prolapse, dilatative cardiomyopathy and intracardiac thrombus is promising but only small patient cohorts have been investigated by means of TCD in these categories. MES in atrial fibrillation, or derived from atheroaortic plaques, have been investigated more intensively, but again larger cohorts need to be explored to draw firm conclusions. In all cardiac diseases there is a lack of large prospective studies allowing to reliably correlating MES with clinical events. Compared to carotid artery disease, the current knowledge about the impact of cardiogenic MES on the patient's risk is sparse. This should encourage the clinical research in this promising field.