Patients can fly, go to high altitudes with precautions after MI

WASHINGTON — Most patients after an MI and other cardiac conditions can return to high altitudes, including air travel, after a few weeks, according to information presented at the American College of Cardiology Scientific Session.

Once high altitude, defined as over 2,500 meters (8,200 feet), is attained, a patient can experience “fairly significant” physiological changes. Most mountains are high altitude, and airplanes fly around 30,000 to 40,000 feet, but the cabins are pressurized to 2,400 meters.

John P. Higgins

Effect of high altitudes

“Altitude does require more work from the [CV] and respiratory systems,” John P. Higgins, MD, MPhil, MBA, FACC, FACP, FAHA, director of exercise physiology at Memorial Herman Sports Medicine Institute in Houston, chief of cardiology at Lyndon B. Johnson General Hospital in Houston and associate professor of cardiovascular medicine at the University of Texas Medical School in Houston, said in his presentation. “People with mild to moderate stable [CVD] can go with the right precautions and preparation to altitude. However, those that have [instability], high risk or a recent procedure should delay travel and be guided by their provider.”

Higgins said bodies work most efficiently at sea level, where the barometric pressure is around 760 mm Hg. At sea level, the partial pressure of inspired oxygen is 149 mm Hg and in-arterial saturation in blood is 98%. In higher altitudes, the partial pressure of the inspired oxygen decreases. At 8,000 feet, or where airplanes are pressurized, the barometric pressure is an estimated 564 mm Hg, the partial pressure of inspired oxygen is 108 mm Hg and in-arterial blood saturation is 60%.

“A healthy individual should have a saturation of 90% or more and be able to handle that without any problems,” Higgins said.

A short-term effect of going to a higher altitude is hypobaric hypoxia, where the body increases its minute ventilation and tidal volume, which causes hypoxic pulmonary vasoconstriction. The body’s cardiac output is increased to compensate for it, Higgins said.

Waiting periods

Higgins reviewed the recommended amount of time before patients can return to higher altitudes and air travel. Patients with CAD and prior MI who are stable experience angina symptoms at lower workloads. Those who had non–STEMI or STEMI should wait 2 weeks before flying or going to a location of high altitude, but if they had a complicated case of MI, 6 weeks is recommended. Patients with a recent diagnosis of ACS who were not revascularized are recommended to have a maximum stress test prior to air travel, but if they are revascularized with PCI and have no complications, they can wait a couple of days. Patients who recently underwent CABG should wait 10 days for gas to be reabsorbed, he said.

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Those with HF should consider certain precautions depending on their class, according to Higgins. Classes I and II are safe to fly, but upon entering moderate altitudes, which can be achieved while skiing or climbing, they will experience reduced functional capacity. In-flight oxygen is recommended for patients with classes III and IV HF. If the patient is already using it, they should increase the rate of oxygen. Air travel and high altitudes for patients with acute decompensated HF are not recommended, but those with post-acute decompensated HF should wait 6 weeks.

Higgins said that patients with a left ventricular assist device (LVAD), are generally safe to fly, but should keep hydrated, have charged batteries and contact an LVAD center at their destination in case of an emergency.

Patients with mild-to-moderate valvular heart disease should have an ECG and an exercise stress test performed to ensure that the hemodynamics are functioning at a proper capacity for higher altitudes. Upon passing, patients should reduce their activity at higher levels of altitude. Patients with severe cases should avoid altitude exposure.

Air travel provides low risk for most patients with arrhythmias, even though higher altitudes and exercise can worsen symptoms. Those with stable arrhythmias should reduce activity levels, while patients with unstable or poor arrhythmias may decompensate or consider in-flight oxygen. If they exhibit many symptoms, they should avoid higher altitudes.

Pacemakers and implantable cardioverter defibrillators have unchanged functionality at moderate altitudes such as air travel and skiing, but Higgins said there aren’t good data on functionality at higher altitudes. Wearable defibrillators are safe for air travel, but patients should carry their device card. “Handheld as well as standing [metal] detectors may interfere with function in some of the devices, so generally we would have you to take a letter and request that they ask for a hand pat-down and not [use] the scanners, or if they are using the scanners, to ask them to not hold the scanner above the device for a prolonged amount of time,” Higgins said. Patients who have recently had a device inserted should wait two days before air travel.

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Patients with congenital heart disease and an intracardiac shunt are most at risk at higher altitudes, as it “may worsen right-to-left shunting in the presence of elevated right-sided pressure,” Higgins said. These patients should consult with a congenital heart disease specialist prior to exposure to high altitudes. Patients with uncontrolled hypertension or cerebrovascular accident can fly within 2 weeks of their diagnosis.

“Altitude requires more work from the [CV] and respiratory systems,” Higgins said. “Patients with mild to moderate stable [CVD] with the right precautions and preparation can fly and go to high altitudes. Unstable, high-risk or recent procedure patients should delay travel and be guided by their provided before doing so.” – by Darlene Dobkowski

Reference:

Higgins J. I Can Do WHAT After My Heart Attack? Presented at: American College of Cardiology Scientific Session; March 17-19, 2017; Washington, D.C.

Disclosure: Higgins reports no relevant financial disclosures.