Non-ST elevation myocardial infarction: a new pathophysiological concept could solve the contradiction between accepted cause and clinical observations.

UNLABELLED

Non-ST elevation myocardial infarction (NSTEMI) and ST elevation infarction have many differences in their appearance and prognosis. A comprehensive search made us form a new hypothesis that a further cause also existsin NSTEMI: an acute, critical increase in the already existing high microvascular resistance in addition to the subtotal coronary artery occlusion. Various findings and studies can be interpreted only by our hypothesis: hemodynamic findings, ECG changes, autopsy reports and clinical observations (different long-time prognosis and different result of acute revascularization therapy in NSTEMI, similarities of NSTEMI with other clinical symptoms where increased microvascular resistance can be supposed without coronary artery disease).

OBJECTIVE

Despite similarities in the underlying pathologic mechanism non-ST elevation myocardial infarction(NSTEMI) and ST elevation infarction (STEMI) have many differences in their clinical presentation and prognosis.

METHOD

A systematic review of the literature about NSTEMI and the blood supply of the myocardium made us form a hypothesis that a further cause also exists in addition to the accepted cause of NSTEMI (subtotal coronaryartery occlusion): an acute, critical increase in an already existing high intramyocardial microvascular resistance.

EVIDENCE

Knowledge about microcirculation disturbances in ischemic heart disease and development of microcirculation damage can be fitted in our hypothesis. Various findings and studies can be interpreted only by our hypothesis: hemodynamic findings, ECG changes, autopsy reports and clinical observations about NSTEMI. The latest ones involve the different long-time prognosis and different result of acute revascularization therapy in STEMI and NSTEMI. Regarding the repolarization changes on the ECG NSTEMI shows similarities with other clinical symptoms where increased intramyocardial microvascular resistance can be supposed without coronary artery disease: false positive exercise stress test, supraventricular tachycardia, left ventricular strain and conduction disturbances.

CONCLUSION

The acute treatment of NSTEMI should aim to improve the blood inflow to the stiff myocardiumand/or impaired microvascular system and decrease the high microvascular resistance.