The Heart & Diving

The Heart & Diving


Statins are a class of drugs prescribed to lower high blood cholesterol and thus prevent heart attack and stroke. They reduce both LDL cholesterol ("bad cholesterol") and inflammation in the arteries. Statins work by inhibiting a liver enzyme that is involved in the production of cholesterol. Though they are most effective at lowering LDL cholesterol, they may also contribute to raising HDL cholesterol ("good cholesterol").

Common statins include the following — listed first by their generic name and, in parentheses, their brand name:
  • Atorvastatin (Lipitor)
  • Cholestipol (Cholestid)
  • Colesevalam hydrochloride (Welchol)
  • Fluvastatin (Lescol)
  • Lovastatin (Mevacor)
  • Ezetimibe (Zetia)
  • Ezetimibe combined with simvastatin (Vytorin)
  • Fenofibrate (Tricor)
  • Pravastatin (Pravachol)
  • Rosuvastatin (Crestor)
  • Simvastatin (Zocor)

Clinical trials sponsored by the companies that manufacture these drugs have found rare and mild side effects. In a carefully designed trial known as IDEAL, however, almost 90 percent of subjects reported side effects, almost half of them serious. Adverse effects of statins that have been noted in the medical literature and that could interfere with diving include the following:
  • Dyspnea (discomfort or difficulty breathing)
  • Muscle pain
  • Tendon complications
  • Digestive problems
  • Rush or flashing
  • Increased blood sugar or type 2 diabetes
  • Cognitive dysfunction (Some studies report that up to 75 percent of those on statins experienced cognitive dysfunction determined to be probably or definitely related to the statin therapy; the severity of the cognitive deficits were clearly related to statin potency.)
  • Fatigue (Almost half of those in a 2012 study reported a significant increase in fatigue while taking statins.)

The most common statin side effect is muscle pain. It occurs in about 20 percent of those taking statins. This pain may feel like aches, soreness, tiredness or weakness in your muscles. The pain is sometimes described as mild discomfort, but it is sometimes severe enough to make daily activities difficult. Scientists suspect the occurrence of pain is due to the fact that statins block production of a molecule the body uses to generate energy, called CoQ10; clinical trials are currently exploring whether taking CoQ10 supplements can prevent this side effect. Routine use of CoQ10 supplementation is not recommended, however, even though there are few safety concerns with such supplementation.

Very rarely, statins can lead to a kind of life-threatening muscle damage called rhabdomyolysis; it causes severe muscle pain and may result in liver damage, kidney failure and death. Rhabdomyolysis is especially likely to occur in those who take statins in combination with other drugs such as antibiotics and antidepressants or in those who take a high dose of statins.

Some people who take statins may develop nausea, gas, diarrhea or constipation. These side effects are rare.

A rash or flushing can also occur after taking a statin. This is more likely to occur in individuals who take a statin and niacin together, either in a combination pill such as Simcor or as two separate medications.

The FDA warns on statin labels that some people taking statins have developed memory loss or confusion; these effects are reversed when the medication is halted. Conversely, there has also been evidence that statins may help with brain function — in patients with dementia or Alzheimer's, for example. This effect is still being studied.

But no matter what side effects individuals taking statins may experience, it is important that they not stop taking the medication without talking to their doctor. It is also important that those who take statins minimize changes in their lifestyle, diet and over-the-counter medications, especially during dive-related travel.

Risk factors for statin side effects include the following:
  • Taking multiple cholesterol-lowering medications
  • Being 65 or older, female or having a smaller body frame
  • Having kidney or liver disease or type 1 or 2 diabetes
  • Drinking too much alcohol (more than two drinks a day for men age 65 and younger or more than one drink a day for women of all ages and men older than 65)

In addition, problems are more likely in those who take both statins and the following drugs:
  • Antimalarials, such as chloroquine and hydroxychloroquine (Plaquenil)
  • Thyroid medications

Effect on Diving

Though the side effects of some statins may interfere with diving, they may nevertheless offer overall health benefits.

One of the effects of statins is an increase in the body's production of nitric oxide. This helps to preserve the integrity of the endothelium (the inner lining of the blood vessels), to reduce injury from ischemia and/or reperfusion (a procedure that restores circulation after a heart attack or stroke) and to depress interdependent inflammatory and coagulation activity — all of which could provide protection against decompression sickness (DCS). On the other hand, a study of healthy divers who took either a statin or a placebo several days before a dive found no difference in their risk of postdive venous gas bubbles. Thus taking statins specifically to prevent DCS does not appear to offer any benefit, especially in view of the possibility of adverse side effects.

If you are over age 45 and are already taking statins for medical reasons, you need to answer "yes" to at least two questions on the Recreational Scuba Training Council (RSTC) Medical Statement (see the "Physical Activity Recommendations" section for details regarding this form):

Q: Are you presently taking prescription medications? (with the exception of birth control or anti-malarial)?

Q: Are you over 45 years of age and can answer YES to one or more of the following?
  • Have a high cholesterol level

These two positive responses signal a pre-existing condition that may affect your safety while diving and that calls for a thorough medical examination to check for the presence of other risk factors or signs of cardiovascular disease. Indeed, anyone who is over age 45, who is at high risk of cardiac problems or who has any signs of cardiovascular disease should see a physician at least once every year.

It is also of note that one-time clearance to dive does not preclude progression of a disease, so any changes in your health status should prompt another medical examination before you dive again. Divers should also be mindful of the fact that they may be required to fill out a new RSTC Medical Statement before any dive and that they may be denied permission to dive based on their responses. However, most dive operators will accept evidence of recent medical clearance for diving. If you are ever in any doubt about your fitness to dive, discuss your status with your dive operator in advance.