In the July 2015 issue of Undercurrent, an article titled “A better heart-check tool than a stress test?” discusses the possible benefits of a coronary calcium scan for older divers to reduce the risk of experiencing a heart attack while diving.1 This article is a follow-up to a May 2015 Undercurrent report about an overweight 65-year-old diver who died shortly into his dive while on a dive trip.2 That article, which considered preventive options such as a stress test, also presented views from Dr. Alfred Bove and DAN’s Dr. Petar Denoble and Dr. James Chimiak, who agreed with the American College of Physicians (ACP) guidelines that recommend a graded and individualized approach to preventive testing and diagnostics.
Another physician suggests in the July 2015 article, however, that older divers should have a coronary calcium scan, which he claims may provide information that will help them avoid a heart attack on their dive trips. Many walk-in clinics offer the test at a low price. “A coronary calcium scan can tell you years before a positive stress test that you are headed in that direction [of significant coronary disease] so that you can do some kind of intervention,” he said. While the statement has merit, it may be misleading in this context.
We’ve just recently returned from the first field trip for the left ventricular hypertrophy and risk of cardiac death in divers study in Bonaire (August 31-September 7). For the first time, we field tested the study logistics and the protocol. The dive trip was organized by Down Under Surf & Scuba in Raleigh, N.C. Out of 36 subjects in the group, 25 were qualified participants over 40 years of age and actively participated in the study. Most of the baseline testing was completed prior to the trip in four sessions: two at DAN Headquarters and two at the dive shop. Five new subjects joined us from other parts of the country and were pre-screened upon arrival to Bonaire.
The Buddy Dive Resort was our central study location. They were very accommodating and allowed us to use their main classroom as a lab. The classroom was at the waterfront where most divers enter and exit water or board the boat for the boat dives.
The plan was to get every participant scanned by echo twice after a full day of diving and once in the morning after a night’s rest. We took take a resting electrocardiogram (ECG) to monitor heart rate variability after a full day of diving on select dive days. All divers carried the Holter Monitor during at least one dive and were asked to record the depth and time of all their dives.
The compliance was nearly perfect. In fact, the only delays were related to travel time back from some remote dive sites. We completed a total of:
- 100 echo scans
- 50 resting ECGs
- 24 underwater Holters
- Nearly 500 recorded dives
The research team included cardiologist Dr. Douglas Ebersole, two professional echo cardiographers Brandy Emory of Lakeland Clinic and Lisa Caudill of Duke and myself. They did an excellent job maintaining the tight schedule and were well received by all of the participants. They even had time to join participants on some dives.
Scott Powell, the manager of Down Under Surf & Scuba and Rochelle Wright, a DAN Member Services specialist, managed all of the logistical challenges so we were able to complete our study. We’re very thankful for their support as well as the overwhelming support from the participants. We appreciate your participation and thank you for helping us to work toward improving diver safety.
Photography and Post by: Petar Denoble, MD, D.Sc.