Cardiovascular diseases are the most common cause of morbidity and mortality in developed countries and are responsible for one-third of total deaths.1,2 The prevalence of Coronary Artery Disease (CAD) is increasing in Turkey and other developing countries. There are many risk factors affecting the emergence and course of the disease. The most common cause of CAD has been reported as coronary atherosclerosis.3 Coronary Angiography (CAG) continues to be the standard approach used in the diagnosis of CAD. CAG is an imaging method used to visualize the coronary arteries that feed the heart and to determine whether there is narrowing in these vessels.4 CAG is an invasive method used in the diagnosis of the heart, an organ with high vital value. Therefore, individuals to be administered CAG experience anxiety and fear of death due to the uncertainties associated with CAG.5 The main causes of anxiety in patients scheduled to undergo CAG have been listed as lack of information about the CAG procedure, long waiting times, fear of death, and the outcomes of the CAG procedure.6 Anxiety has been defined as the reaction to any threat, the cause of which is unknown and based on internal conflict in the individual.7 Physiological changes that arise from anxiety can negatively affect vital signs and delay the recovery process after CAD. For these reasons, it is important to assess and effectively reduce anxiety levels, especially before CAG.8, 9, 10 One of the essential responsibilities of healthcare professionals has been indicated to maximize the psychological and physical health of patients before invasive procedures and to help patients cope with anxiety.11 In this context, in addition to pharmacological treatment methods, non-pharmacological methods are frequently used to reduce the anxiety of patients.12 These non-pharmacological methods include having the patient listen to classical music,4 having the patient perform muscle relaxation exercises and listen to music,13 having the patient meet with patients who underwent the invasive procedure in question,14 and administration of aromatherapy during the invasive procedure.15,16 Complementary non-pharmacological therapies such as aromatherapy have certain advantages over other methods in that they are inexpensive, non-invasive, easy to apply, and free from chemical side effects.17 Aromatherapy features the use of a number of essential oils, e.g., lavender oil, geranium oil, jasmine oil, rosemary oil, rose oil, evening primrose oil, and chamomile oil, to relieve psychological symptoms such as anxiety and depression.18 Lavender in particular has been used in traditional medicine for a long time. The use of lavender oil is known to affect the central nervous system; giving rise to the release of encephalin, serotonin, and endorphins.19 Lavender essential oil is produced from lavender plants using mostly steam distillation method. There are about 39 lavender species, but the four most commonly used ones are Lavandula (L.) Angustifolia, L. Latifolia, L. Stoechas, and L. x Intermedia.20 Among these species, L. Angustifolia is the most widely cultivated lavender species and is therefore often referred to as the lavender. Also, L. Angustifolia is widely used in different contexts.21 It has been reported in many studies that inhaling lavender oil reduces patients' anxiety and some vital signs.22, 23, 24, 25 In view of the foregoing, the aim of this study was to assess the effect of aromatherapy administered before CAG on anxiety levels and physiological parameters.

H1: Aromatherapy administered before CAG has a positive effect on the pre-procedure anxiety levels and physiological parameters of patients.