Google gives virtually no results for "índice académico a grado", and none that indicate what it means, but I think we can probably assume that it's this. The terms "índice acumulado" and "índice a grado" are probably based on American English "cumulative GPA" and "degree GPA".

"Courses taken at any IU or Purdue campus and included in the student's program of study will be used in calculating the final GPA at time of the degree. This "degree GPA" will only appear on the IU transcript upon completion of the degree.
In some cases, schools calculate a degree GPA which may vary slightly from the cumulative GPA as it appears in the summary portion of the transcript. This is due to differences in program requirements and is used most often in programs where students earn Purdue degrees."
http://registrar.iupui.edu/gpa.html

If it "may vary slightly", presumably it is often the same, as in your case.

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Note added at 1 hr (2014-04-14 06:28:43 GMT)
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Si este I.A.G. funciona como el DGPA norteamericano, podría ser diferente del I.R.A.A. (CGPA) si el estudiante ha cambiado de universidad:

"Degree (Summary) GPA: The weighted average of all grades received at your degree-granting school. The total semester hours associated with that GPA are also reported.
Cumulative GPA: The cumulative average of all grades received at all undergraduate schools you have attended. The total semester hours associated with that GPA are also reported."
http://talk.collegeconfidential.com/discussion/comment/48863...

"Cumulative Grade Point Average (CGPA)
Cumulative Grade Point Average (CGPA) is defined as the grade point average of all courses, institutional and transferred, taken at the same level (non-credit, undergraduate, or graduate), subject to the rules regarding repeated courses as described below. The CGPA is calculated by dividing the quality point total by the total number of credit hours attempted.
Degree Grade Point Average (DGPA)
The Degree GPA (DGPA) is defined as the grade point average of all courses acceptable for credit in a students' current degree/program subject to the rules regarding repeated courses as described below. The DGPA is calcluated by dividing the quality point total by the total number of credit hours for courses acceptable for credit in the current faculty or school."
https://umanitoba.ca/student/records/grades/687.html

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Note added at 5 hrs (2014-04-14 10:42:36 GMT)
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It could be that in Venezuela this difference between CGPA (all degree courses, including transfer courses) and DGPA (all courses taken at the degree-awarding institution) does not apply, and that "índice académico acumulado" and "índice académico de grado" are actually the same thing (though it's hard to believe that they are actually identical, otherwise why have two different terms?). In any case, since you'll want to use two different terms in English, I think "degree GPA" will do for this.