Unknown Which is not true of cardiopulmonary resuscitation (CPR)? A Closed chest massage is as effective as open chest massage. B The success rate for out-of-hospital resuscitation may be as high as 30% to 60%. C The most common cause of sudden death is ischemic heart disease. D Standard chest massage generally provides less than 15% of normal coronary and cerebral blood flow. 💡 Explanation Which is not true of cardiopulmonary resuscitation (CPR)? ✓ Correct Answer: A. Closed chest massage is as effective as open chest massage.