To the Editor.
—We welcome the cautionary note of Ball et al1 concerning the use of intravenous (IV) digital subtraction angiography (DSA), but we believe that their conclusion that this procedure is more dangerous than standard angiography is not justified, since their two groups are not comparable.As the authors point out, patients with poor clinical status may be subjected to IV DSA when standard angiography is contraindicated. More patients with angina or ischemic heart disease will therefore be referred for DSA, so, naturally, more patients will experience these symptoms during the procedure. A true comparison is possible only by randomly selecting patients for the two procedures, which would be impractical as well as unethical.We doubt that the permanent neurologic deficit that occurred in one patient one day after IV DSA was related to the procedure. Clinical details are scanty (was a computed tomogram obtained?), and a progressing stroke that occurs so long after the procedure is more likely to be a chance event. The authors do not state the reasons for performing IV DSA on
John WN, Nathan MB. Intravenous Digital Subtraction Angiography. Arch Neurol. 1986;43(8):756. doi:10.1001/archneur.1986.00520080008006