thrombolysis

Thrombolysis is the chemical way to dissolve a blocking clot — a drug that, in effect, melts the cork out of the artery so blood can flow again. In a heart attack it offers a route to reperfusion when mechanical means are not immediately available.

The drugs used (such as tissue plasminogen activators) activate the body's own clot-dissolving system, converting plasminogen into plasmin, an enzyme that breaks down the fibrin holding the thrombus together. Given intravenously, they can reopen an occluded coronary artery within minutes to an hour, restoring flow to the threatened muscle.

Thrombolysis is mainly used in STEMI, especially where primary angioplasty cannot be performed quickly. Its great advantage is that it can be given almost anywhere, including before reaching hospital; its main drawback is bleeding, because the same clot-dissolving action can disturb protective clots elsewhere — most seriously, bleeding into the brain. It is therefore avoided in people at high bleeding risk and is less effective than timely angioplasty.

Thrombolysis dissolves an existing clot, whereas antiplatelet and anticoagulant drugs mainly prevent new clot from forming or growing; the two are often used together but serve different roles.