JFOA

Introduction

Cardiovascular Disease (CVD) affects about 523 million people worldwide and causes roughly 18.6 million deaths each year [1]. Over recent decades, the prevalence of CVD has increased globally, leading more individuals with chronic heart conditions to travel by air. An estimated 1.5 to 4.5 billion airline passengers each year [2], many travellers have underlying cardiovascular issues and might be exposed to flight-related physiological stressors such as hypobaric hypoxia and sympathetic activation. The incidence of in-flight medical emergencies has been evaluated in large observational studies involving 744 million airline passengers. Approximately 1.6 per 100,000 passengers required in-flight medical assistance. Cardiovascular presentations predominated, with syncope or near-syncope accounting for 32.7% of events, followed by other cardiovascular symptoms (7.0%). Although in-flight deaths were rare, 31 of 36 fatalities were attributable to cardiovascular causes, most commonly cardiac arrest [3].

In parallel, the use of advanced cardiovascular therapies has expanded considerably. In the United States, about 200,000 permanent pacemakers and more than 300,000 Cardiac Implantable Electronic Devices (CIEDs) are implanted each year [4,5]. Additionally, in the last decade (2013-2022), 27,493 patients were supported with continuous-flow Left Ventricular Assist Devices (LVADs), forming one of the largest contemporary cohorts of patients receiving durable mechanical circulatory support [6], and a total of 4,000 heart transplants occurred in 2023 alone [7].

As more patients with advanced cardiovascular disease, advanced cardiac therapies, and heart transplants resume routine daily activities, including air travel, primary care and family physicians are increasingly asked to advise on travel safety. This review provides a practical overview of cardiovascular risks associated with air travel, outlines pre-travel assessment and counseling strategies suitable for outpatient practice, and highlights situations in which referral to cardiology or transplant specialists is recommended.

Physiological Impact of Cabin Altitude on Oxygenation and Gas Exchange

At higher altitudes, barometric pressure decreases, reducing the partial pressure of inspired oxygen (PiO₂). Although commercial aircraft cruise at 30,000-40,000 feet, cabin pressurization maintains an equivalent altitude of up to 8,000 feet, as required by the U.S. Federal Aviation Administration [8]. At this altitude, PiO₂ falls from approximately 150 mmHg at sea level to 110-125 mmHg [9], resulting in lower arterial oxygen tension and potential hypoxemia in susceptible individuals [10].

In healthy travellers with normal cardiorespiratory reserve and a sea-level PaO₂ above 95 mmHg, this shift moves the individual along the flatter portion of the oxyhaemoglobin dissociation curve (Figure 1) [11]. The result is typically a modest 3-4% fall in arterial oxygen saturation, which is usually well tolerated and often asymptomatic [12]. However, patients with cardiovascular disease, particularly those with heart failure or limited cardiac reserve, may experience clinically significant effects, including dyspnea, chest discomfort, palpitations, fatigue, light-headedness, or reduced exercise tolerance, due to hypoxemia and increased sympathetic activation during flight [3].

Figure 1: Oxyhemoglobin dissociation curve illustrating the effects of altitude-related hypoxia in healthy individuals versus patients with Chronic Obstructive Pulmonary Disease (COPD). PO₂: partial pressure of oxygen. Adapted from [11] with permission.

Disease-Specific Considerations for Cardiovascular Diseases During Air Travel

According to guidelines and consensus among various aviation societies and authorities, certain cardiovascular conditions are considered absolute contraindications for air travel. These conditions carry significant risks to individuals’ health and safety during the flight, highlighting the need for a thorough evaluation before travel [13]. Cardiovascular conditions are absolute contraindications to air travel (Table 1) [14].

Table 1: Absolute Contraindications to Air Travel in Cardiac Patients.

Ischemic Heart Disease (IHD)

Ischemic heart disease (IHD) is the most common cause of in-flight medical emergencies, largely due to its high prevalence in the general population. Aerodynamic stressors can act as triggers that worsen the condition [15]. The IHD disease is classified into a) chronic coronary syndrome and b) acute coronary syndrome, which have somewhat different air travel recommendations.

Chronic Coronary Syndrome

Often referred to as stable coronary disease, these conditions usually present as angina [16]. Leading U.S. and European societies (ACS/ ESC) do not recommend pre-flight stress testing for stable CCS. However, if new ischemic symptoms appear or existing symptoms worsen despite treatment, a thorough evaluation is necessary [17]. In cases of stable CAD, fitness for air travel is evaluated based on the severity of angina, the complexity of elective angioplasty, and the stability of the patient following CABG surgery. When CAD is stable, patients are considered fit for air travel depending on the severity of angina, the intricacy of elective angioplasty, and their stability after CABG (Table 2) [14,17].

Table 2: Air Travel Recommendations for Patients with Chronic Coronary Artery Disease.

Acute Coronary Syndrome

Acute Coronary Syndromes (ACS) include Unstable Angina Pectoris (UAP), non-ST Elevation Myocardial Infarction (NSTEMI), and ST-Elevation Myocardial Infarction (STEMI) [18]. In the immediate aftermath of these events, patients face an increased risk of postinfarct complications, which heightens their risk for air travel [19]. Recommendations for air travel following ACS are primarily based on theoretical insights into in-flight stressors, given the significant lack of robustly powered studies on cardiovascular safety in this context [20]. The evolving perceptions of risk have prompted more lenient guidelines for permitting air travel after ACS events, exemplified by the American College of Cardiology’s decision to remove guideline statement concerning post-NSTEMI air-travel [21]. Recognizing that not all ACS patients are alike, it is a sensible approach to utilize selected nonmodifiable clinical predictors in conjunction with appropriate risk calculators, such as the Zwolle risk score, to customize risk stratification for evaluating flying fitness post-ACS [14,2224] (Table 3).

Table 3: Air Travel Recommendations Following Acute Coronary Syndrome (ACS).

Heart Failure, Valvular Heart Disease, and Cardiomyopathies

Overall, heart failure, valvular disease, and various cardiomyopathies follow similar recommendations and assessments related to air travel [25]. Patients who are functionally stable with heart failure (NYHA Class I and II) in the 4-6 weeks before flying, including those with significant left ventricular systolic impairment, can tolerate mild hypoxia in the aircraft cabin and are considered fit to travel [26]. However, acute heart failure decompensation or recent hospitalization pose a significant risk for travel, requiring a careful assessment and optimization of cardiac status before confirming fitness to fly. All triggers of acute decompensation should be addressed, and patients should be monitored for clinical stability over 6-8 weeks after discharge, with Implantable Cardioverter Defibrillators (ICDs) implanted when clinically indicated [27-29] (Table 4).

Table 4: Air Travel Recommendations for Patients with Heart Failure.

Left Ventricular Assist Devices (LVADs)

The use of Left Ventricular Assist Devices (LVADs) has increased as a bridging therapy [29]. Although the idea of LVADs might seem unsettling, patients who are clinically stable are generally considered safe for air travel. Notably, no significant issues have been reported with airport security screening devices or in-flight electronic systems [30-32] (Table 5).

Table 5: Air Travel Recommendations for Patients with Left Ventricular Assist Devices (LVADs).

Cardiac Arrhythmias

Cardiac arrhythmia is broadly divided into tachyarrhythmias and bradyarrhythmias. Although in-flight hypoxia and increased sympathetic activation can increase the risk of cardiac arrhythmias, significant arrhythmias during air travel are rare [13]. Passengers with uncontrolled symptomatic cardiac arrhythmias should avoid traveling and seek specialist evaluation, whereas those with stable chronic arrhythmias are generally considered fit for air travel [29,33] (Table 6).

Table 6: Air Travel Recommendations for Patients with Cardiac Arrhythmias.

Cardiac Implantable Electronic Devices (CIED) and Pacemakers

It is estimated that over 300,000 new Cardiac Implantable Electronic Devices (CIEDs) are implanted annually in the U.S. [34]. Patients with Cardiac Implantable Electronic Devices (CIEDs) are classified into two groups: those with newly implanted devices and those with chronic implants. Travelers with recently implanted CIEDs may be cleared for air travel if they are stable, have no pneumothorax, controlled pain, and confirmed normal device function [35]. If a pneumothorax develops, air travel should be postponed for at least two weeks after its resolution [36]. For individuals with chronic CIEDs, air travel is not recommended if there is abnormal device function or a recent ICD shock, and they should consult an electrophysiologist and aviation medicine specialist before traveling [37]. Minimal interference with Cardiac Implantable Electronic Devices (CIEDs) has been reported from airport security systems and in-flight avionics, and these devices are generally well tolerated [38]. Left-sided electrophysiological procedures or ablation place patients at an increased risk of systemic embolization due to potential thrombus formation from catheters or endocardial lesions. Therefore, anticoagulation is strongly recommended to reduce this risk, and unnecessary travel should be postponed [14,35] (Table 7).

Table 7: Air Travel Considerations for Patients with Cardiac Implantable Electronic Devices (CIEDs).

Postcardiac Surgery and Cardiac Transplant

Stable cardiac surgery patients are usually cleared for travel 10 to 14 days after surgery, as long as their haemoglobin levels are checked beforehand. If complications such as pneumothorax or pneumomediastinum occur, travel should be delayed until full recovery and the resolution of air build-up. Currently, there are no clear guidelines regarding air travel after heart transplantation. However, a study suggests that patients can safely fly, but the study participants had at least three years post-transplantation before air travel [39]. Long-haul flights pose significant challenges for heart transplant recipients due to their immunosuppressed status, making it crucial to implement appropriate prophylactic measures to protect their well-being during travel [39].