Abnormal Stress Test

I am a 46 year old male, 73", 225 lbs.  I have been active almost my entire life.  In March 2008 I had a general physical exam with my primary physician and blood test.  My physician has some concern with my cholesterol numbers (164 triglycerodes, 210 total cholesterol, 38 HDL and 138 LDL).  He wanted me to excercise a minimum of 40 minutes 2 to 3 times per week, lose weight (I have since lost 5 lbs), cut down my alcohol consumption and return in 3 months for follow-up.  Since that time, I have made alot of efffort to walk and/or run 3 to 4 times per week.  I mostly run.  When I run, I usaully begin by walking for 3 minutes at 4 mph, running for 36 minutes at 6.7 mph (with the last minute at 8 mph), and walking for 3 minutes at 4 mph (total workout 42 minutes).  My heart rate during this workout exceeds 160 beats per minute.  I have never felt any shortness of breath or chest pain whatsoever while excercising (or at any other time).

On 07/25/08 I took a stress test for a pre-employment physical.  At the end of the supine stage my heart rate was 99 BPM and ST segment was 0.4.  At the end of stage 1 my heart rate was 111 BPM and ST segment was -0.8 mm.  At 52 seconds into stage 3 my ST segment was -1.5 mm.  At 2 minutes into stage 2, which was the termination of test by the PA because of the excessive ST segment depression, my heart rate was 135 BPM (target 147 BPM) and ST was -1.4.  At 1 minute into recovery my heart rate was 107 BPM and ST segment was -0.5.  At three minutes into recovery my heart rate was 99 BPM and ST segment was -0.6.  During the test I experienced no discomfort at all.  In fact, I was barely breaking a sweat and was very surprised when the PA concluded the test because of what she described as the excessive ST segment depression.  My BP during the entire test, from start to finsih, was 140/80.

The PA was very concerned with the results of the test (I felt like I had one foot in the grave) and told me not to excercise until I saw a cardiologist.  Later that afternoon, I went to my primary physician for a cardiology referral.  The took a resting EKG, which was normal, and made a cardiology referral.

I have done some research into stress tests and saw that the test does not need to stop unless the patient suffers chest pain (not in my case) or ST depression reached -3.0 (not in my case), so I wish the PA had allowed me to reach my target heart rate (147 BPM) before terminating the test.  I also saw that if not for the pre-employment physical (I was applying for a reserve police offficer position), I would not have been referred to a stress test.  This stress test result was a complete shock to me.  Should I be unduly concerned?  Is it likely that I have CAD and am a heart attack candidate?  Any insight is appreciated.  

[richardvf]

As indicated in the above post, my PA as a result on my 07/25/08 abnormal pre-employment stress test result referred me to a cardiologist.  The cardiologist completed an echo stress test in which I was allowed to reach 100% of my target heart rate and complete stage 4 (12 minutes) of the Bruce Protocol.  The echo stress test showed  excessive ST segment depression, which was gone within one minute into the rest period, and abnormal heart wall movement.  The cardiologist recommended cardiac catheterization, which was completed on 08/25/08.  Well, the cath was normal.  No evidence of coronary artery disease.  The cardiologist told me that the results of the prior stress tests were false positive results.  So basically, I was freaked out for a month and received an outpatient surgical procedure (at a cost of several thousand dollars to my insurance company I am sure) for no reason. I am thankful that I don't have CAD though.  I am curious.   How often does this occur?