On a stress test the double product achieved was 28,512. is this cause for concern?

Several issues here:: Double product=highest systolic pressure times max heart rate, e.g 169 mmHg x 169 BPM = 28561. 170 BPM=not very high for age; predicted max near 190. Stress tests=crucially dependent on achieving max predicted rate; else sensitivity markedly ↓ed for detecting >75% narrowing of major heart arteries. Yet all stress tests miss most (nearly all) disease. Thus would not rely; use better strategies.