Which artery am I infarcting?

ECG leads vaguely correspond to areas of the myocardium supplied by the coronary arteries.
localisation of coronary artery territories

If you would like to pay them, UpToDate have this article about the anatomic correlations of ECG changes in acute MI.

If you are cheap like me, you would get this NEJM article from CIAP.

 

References

Peter J. Zimetbaum, M.D., and Mark E. Josephson, M.D. Use of the Electrocardiogram in Acute Myocardial Infarction N Engl J Med 2003; 348:933-940March 6, 2003