intracoronary thrombolysis showed the chronological order of clinical
electric and biological changes following the reestablishment of coron
ary flow. These changes make up the reperfusion syndrome; ST segment c
hanges are part of this syndrome. They occur in practically all cases
at the moment of reperfusion. The ST elevation may regress more or les
s rapidly or, on the contrary, increase transiently to a greater or le
sser degree. When associated with other criteria of reperfusion-enzyme
changes, arrhythmias, ST changes contribute to the indirect diagnosis
of reestablishment of coronary flow. Rapid decrease in ST segment ele
vation is usually associated with a good myocardial outcome. The progn
ostic significance of transient increases in ST elevation - so called
''reperfusion ischaemia'' - is not fully understood, in particular its
relationship to myocardial reperfusion injury. The myocardial prognos
is after reperfusion may be the ''biological'' sum of cellular lesions
due to ischaemia and reperfusion.