AINsight: Cardiac Calcium Scores for Pilots

To no one’s surprise, pilots are often reluctant to seek medical screenings. The usual cliché (read: excuse) given is to avoid opening the proverbial “can of worms” with the FAA. After all, no good deed goes unpunished. I understand that fear from my own years as a professional pilot, but even back then I did not shy away from appropriate medical screening and care—damn the torpedoes!

As an AME, my opinion is that opening that can of worms sooner rather than later may save a pilot from a severe medical complication and the inherent roadblocks to their future aviation medical certification, let alone their health itself.

Pilots have been especially reluctant over the years to obtain cardiovascular screening, which may have been recommended by their primary care physicians or even their AMEs. The rationale for such recommendations includes risk factors such as the inevitable aging process, obesity, smoking history, alcohol consumption, family medical history, cholesterol levels, and symptoms reported by the pilot that may be concerning for cardiovascular disease.

One modality for cardiovascular screening that has become quite popular, both with patients and physicians, is the evolution of the coronary calcium score. Computed Tomography (CT) scanning became an inexpensive, quick, and non-invasive tool to obtain a rough idea of calcifications in coronary arteries. In the 1990s, Arthur Agatston, MD, refined a method to more specifically quantify the amount of calcium in each of the main coronary vessels.

More recently, a further evolution of these technologies has included formal flow analysis in each of the vessels. This modality, Coronary Computed Tomography Angiography (CCTA), uses a highly refined software analysis of each individual vessel. This provides an accurate and non-invasive assessment, which is termed Fractional Flow Reserve (FFR). I consult regularly with a group of research-based cardiologists (who work directly with Agatston) who believe that the CCTA-FFR technology will eventually replace the traditional “let’s stick a tube all the way into your heart” catheterization and angiogram for routine diagnostic evaluations. The formal catheterization procedure uses a contrast agent injected in real time into the coronary vessels, viewed under continuous X-ray evaluation (fluoroscopy).

If an artery blockage (stenosis) is suspected by any modality, then, of course, a catheterization and angiogram procedure permits both an additional real-time analysis and, if required, the placement of a cardiac stent to hold open the offending artery. More serious and/or multi-vessel disease may require cardiac bypass surgery for therapeutic treatment of the disease.

Sounds great! Calcium scoring! I’m all in! Let’s go for it!

But wait. Is calcium scoring truly reflective of heart disease? What are the risks and benefits?

These modalities are most certainly worth pursuing, with some caveats.

The earlier version of calcium scoring only provides a general assessment of calcium accumulation in the heart. This, on its own, is of at least some value. The greater the amount of calcium, the more it can be inferred that trouble may be brewing inside the heart (there is, to date, no MEL procedure for the heart, so it may become a no-go item if not working well). Calcium scoring provides a modicum of initial screening to an otherwise reluctant pilot. Additional diagnostics may later be required.

The calcium deposits only reflect hard plaque on the vessel walls. While a buildup of hard plaque is concerning (as it may inhibit blood flow in the vessel), it is not the entire story. What cannot be measured by these earlier modalities is the soft plaque. These plaques are composed of inflammatory cells and cholesterol-based lipids.

You will notice that I mentioned inflammatory cells first. Compared to the hard plaques that are stable and gleefully adhering to their individual territories in the vessels, the soft plaques, on the other hand, are more dangerous. These plaques are more prone to rupture.

When this happens, due to their inflammatory nature, small blood clots may suddenly form in vessels that did not appear to be overtly blocked with calcium-stabilized plaque. When soft plaque breaks off, and with the resultant blood clotting, suddenly the coronary vessel is occluded. As you have already surmised, a blocked vessel can lead to all sorts of alarming symptoms and even to the dreaded myocardial infarction (heart attack).

Given that hard plaques are relatively stable, they can be followed over time with serial screenings until an intervention is medically indicated.

The soft plaques, however, sneaky little beasts that they are, are more difficult to evaluate. This is because they are not yet calcified, cannot easily be assessed with routine CT scanning, and are therefore hiding covertly waiting for an opportunity to wreak havoc on an unsuspecting pilot.

This does not sound very optimistic. Is Dr. Bob simply trying to frighten pilots yet again? Hardly.

The ongoing themes in my writings begin with relevant medical conditions and risk factors that I want pilots to be aware of. Then, I offer recommendations on how to medically assess and treat risk factors and disease. Finally, and to the great relief of pilots, I offer strategies for continuing and/or regaining their FAA medical certification.

Can anything be done about the soft plaques?

Without trying to sell the use of any medication, this is one time that I will espouse the use of statin medications. These include the popular atorvastatin (Lipitor), rosuvastatin (Crestor), and their cousins. The disclaimer is that there are risks and benefits to the use of any medication or therapy, and a frank discussion with the medical provider is always recommended.

Consider also the risks and benefits of avoiding cardiac screening or treatment and eventually having a heart attack (hint: more risk than benefit).

While statins potentially shrink plaques, they provide a more important function. Statins stabilize vulnerable soft plaques so that they are less likely to rupture and cause blood clots.

One of the ways they do this is by depositing calcium into the soft plaques to reinforce their stability. The statin also reduces the inflammation that contributes to soft plaque ruptures. It is this anti-inflammatory process that is every bit, if not more so, important than simply, over time, affecting regression of the plaques themselves. High-risk lesions eventually transform into somewhat lower-risk lesions.

Given their mechanism of action, calcium scores are expected to rise over time when taking statins. This must be taken into account when evaluating future scoring studies. Scores may elevate the risk that is actually being lowered, a yin-yang in cardiology.

There are additional treatment options available, but those discussions are beyond the scope of this blog.

The FAA, while condoning many different medical screening modalities, must also face the reality of the results of said screenings. If true coronary artery disease is suspected, the FARs come into play. There are only about 15 specifically disqualifying medical conditions noted in the FARs. These are immediately grounding and only through a special issuance authorization may a pilot begin flying again.

Heart-related symptoms and findings comprise six of the disqualifying conditions. Once again, there are no substitutes for the heart. Take good care of it.

On January 26, the FAA published specific guidelines regarding the use of the various cardiac screening modalities discussed above. There is a complex explanatory graph in the “Guide for Aviation Medical Examiners.” This is best discussed with the pilot’s treating physician and AME.

When screening calcium scores approach about 400, this is an indication of a moderate-risk condition. The FAA requires formal diagnostic testing to begin at this level. This may include an exercise stress test with nuclear imaging (nuclear isotope absorbed into heart muscle via standard intravenous blood access; no catheterization is required) to rule out ischemia, which refers to heart muscle starved of blood and hence oxygen.

Once screening calcium scores approach 700, this indicates a potentially high-risk situation. At that point, a more formal imaging modality is required. One option is the traditional catheterization angiogram. However, recently the FAA has begun to also accept the CCTA-FFR. The flow analysis available through FFR has satisfied the FAA’s cardiology consultants that it is truly an acceptable and reliable imaging process without the inherent risks of an invasive catheterization.

Be advised that the FAA is indeed sending letters to pilots to require one of these evaluations if a high calcium score is reported by the pilot, or even if it is simply noted in historical comments in any other medical documents that the pilot may have been required to submit to the FAA for another medical condition.

If cardiac disease is found, the sooner a pilot gets it treated, the better. While it often feels like no good deed goes unpunished with the FAA, cardiac screening may save the pilot’s life. Hopefully, any impacts on the pilot’s FAA medical certification will be temporary.

In conclusion, it may be in your best interest to open that can of worms and see what’s inside. To quote Gene Kranz, NASA’s chief flight director for many space missions (including choreographing the heroic efforts required by his entire team to bring the crippled Apollo 13 spacecraft safely back to Earth): “Work the problem. Let’s not make things worse by guessing.”

Please do not hide from medical screenings and assume or guess that everything will be fine. Work the problem. It is easier to keep you flying if you are still alive.