Abstract: The aging heart has an impaired response to many kinds of stress. In clinical practice, there is a need for senescence-specific therapies to protect against stress and for biochemical markers of senescence to identify those patients most in need of therapy. In isolated rat hearts, in human tissues, and in a clinical trial, we have shown previously that coenzyme Q10 has the ability to protect the heart against stress especially in senescence. We recently have devised a regimen of therapy to protect the senescent heart against stress, combining metabolic therapy (coenzyme Q10, alpha lipoic acid, magnesium orotate, and omega 3 polyunsaturated fatty acids) with physical exercise and mental stress reduction. The preliminary results of this program are promising. In an endeavor to predict the likely response of individual senescent hearts to stress, we correlated the tissue load of mitochondrial DNA deletions and total cellular mitochondrial DNA copy number in human cardiac tissue with recovery of the same tissue from ischemia/reperfusion stress. We found that these mitochondrial markers actually were less predictive of impaired response to stress than age alone. We conclude that the aging heart has a diminished capacity to recover from stress that is not readily predictable by cardiac content of intact mitochondrial DNA and that this recovery can be improved by metabolic therapy combined with physical exercise and mental stress reduction.