**4. Preventing cardiovascular disease**

Aircrew retirement age is increasing and the burden of subclinical, but potentially significant, coronary artery atherosclerosis is unknown in pilots above age 40 [20]. Prevention of CVD in aircrew may be even more problematic than in the general population. The control of CVD should focus on the reduction of behavioral risks (salt, tobacco, alcohol, physical inactivity) and metabolic risks (high BP, diabetes mellitus, and obesity), and on multidrug therapy for treatment of individuals

at high risk of heart attack and stroke based on these risks. Preventive initiatives should make it easier for healthy aircrew to stay healthy, and for those with established CVD or at high risk for CVD to modify their behavior [67]. To prevent the onset of CVD in aircrew, many avenues including healthier lifestyle such as regular physical activity, healthier diet, weight loss, moderate alcohol consumption, and smoking cessation, and the control risk factors can be considered.

Regular physical activity lowers the risk of CVD, improves endothelial and platelet function, and diminishes insulin resistance [68]. In fact, regular physical activity corrects raised BP and lipid profile, increases the level of HDL but lowers that of TC and LDL-c [68–70]. NICE guidelines recommend 150 minutes of moderate intensity aerobic activity per week, or 75 minutes of vigorous aerobic activity. Whilst NICE give only a consensus recommendation regarding the utility of exercise as primary prevention, guidelines from the AHA and ESC give class 1A recommendations with almost identical prescriptions, referring to a solid and consensual body of evidence [17, 71]. It has been reported in a recent cross-sectional study including 22 physically active men, exempt from CVD, that particular features of physical fitness such as aerobic capacity were associated with better cardiovascular control (HRV and BP) during flights. These authors encouraged future studies to investigate the role of physical fitness in reducing the flight-induced stress and related cardiac autonomic alterations for the general population [20].

Diet represents the most significant modifiable factor in the primary prevention of CVD. There is evidence that eating fruit and vegetables have been found to have compelling cardiovascular effects [69]. Epidemiological evidence shows that a diet low in fruits is the third most important risk factor of CVDs following high BP and cigarette smoking, accounting for more than 5 million deaths worldwide in 2010 [72]. The mechanisms of action mainly included the modulation of molecular events and signaling pathways associated with correcting endothelial dysfunction, reducing disorders in lipids metabolism, anti-hypertension, suppressing platelet's function, alleviating I/R injury, inhibiting thrombosis, reducing oxidative stress, and inhibiting inflammation responses [73]. Several studies have highlighted the impact of high-potassium diet on high BP, singularly in the presence of high dietary sodium, using the inward-rectifying potassium (Kir) [74].

There is evidence that modest weight loss (e.g., 5–10%) can reduce CVD risk profile even when the patient remains in the obese range [75, 76]. Modest weight loss has been linked with an improvement in fasting glycaemia, glycosylated hemoglobin (HBA1c), and systolic and diastolic BP and plasma lipid profile (TG, TC, and LDL-c) [77]. Moreover, weight loss can also improve the efficacy of antihypertensive medications. Weight loss should employ a multidisciplinary approach that includes dietary advice, regular exercise, and motivational counseling [17, 78]. Weight loss can also be promoted by anti-obesity drugs and, to a greater degree, bariatric surgery, which appears to decrease CV risk in severely obese patients [79]. There are moves to suggest that, alongside reduction in BMI, reduction in WC as a proxy for reductions in visceral adiposity should become an important target for amelioration of CVD risk.

Four decades ago, epidemiological studies showed the historically J-shaped curve between alcohol consumption and cardiovascular risk [80, 81]. Recently, both cohort studies and meta-analyses corroborated the robustness of the mentioned relationship [82]. These authors argued that abstinence is associated with an increase in cardiovascular risk compared to light drinking and low levels of alcohol consumption associated with a lower level of CHD. Similarly, INTERHEART, NICE, and ACC studies showed moderate to light alcohol use was linked with preventing CVD. Contrastingly, through a large mendelian randomization meta-analysis, Holmes et al. showed that reduction in alcohol intake is linked with reduction

#### *Risk Factors for Cardiovascular Diseases in Aircrew DOI: http://dx.doi.org/10.5772/intechopen.99905*

in CVD risk even in light-moderate drinkers [83]. It is on this basis that the ESC guidelines recommend no safe level of alcohol intake [84].

Smoking cessation is strongly recommended by all guidelines and smoker is likely to use nicotine replacement therapy (NRT), bupropion (a norepinephrine dopamine reuptake inhibitor) and particularly varenicline (a partial nicotine receptor agonist). Evidence suggests the use of NRT outweigh its cardiovascular risks whilst the use of E-cigarettes are still controversial [85].

Lowering BP to an optimal level (<130/80 mmHg) has been found to significantly reduce the risk of CVD [86]. Best proven non pharmacologic Interventions for prevention and treatment of hypertension that are weight loss, health diet, lower intake of dietary Na+, enhanced intake of dietary K+, physical exercise, and moderate alcohol intake approximately impact on SBP by 5, 11, 6, 5, 5, and 4 mmHg, respectively. Specific BP lowering drugs include calcium blockers, diuretics, ACEI, ARBS, and beta-blockers [84]. Medical practitioners are advised to avoid pharmacological inertia characterized by negligence of medical providers to initiate or intensify pharmacological therapy as stated by guidelines [84].

The overall strategy toward risk management for type-2 diabetes patients should focus on BP and lipid control to lower the leading complications of diabetes. Diabetes is treated with diet, exercise, and some antidiabetic medications [87]. Lowering cholesterol by means of drugs such as statins alone or associated with either ezetimibe or anti-proprotein convertase subtilisin/kexin type 9 (PCSK9) monoclonal antibodies (mAbs), has been found to reduce ASCVD risk; however, lipid-lowering diet and physical exercise are also important [88].

In aircrew with heart failure, medications should include B-adrenergic blockers, ACEIs, and more recently Ivabradine and/or sacubitril/ valsartan combination, when appropriate. Implantable cardioverter defibrillators and/or resynchronization should be associated. Exercise training is usually indicated based on the patient response to applied exercise protocols. In patients with CKD, risk factors such as hypertension, type-2 diabetes, and obesity should be controlled [89].

Traditional herbal remedies should be avoided for numerous riveting studies showed their toxicity even if histological and toxicological studies are needed to validate this causal relationship [89]. Antihypertensive treatment reverses myocardial hypertrophy, and additionally reduces repolarization time and its dispersion, the incidence and the severity of ventricular arrhythmia, and the risk of cardiovascular events.

Flight crew represent a high CVD risk subgroup requiring development of a comprehensive prevention and care program to mitigate the elevated risk and improve their quality of life and performance.
