SALBUTAMOL INHALATION HAS NO EFFECT ON MYOCARDIAL-ISCHEMIA, ARRHYTHMIAS AND HEART-RATE-VARIABILITY IN PATIENTS WITH CORONARY-ARTERY DISEASEPLUS ASTHMA OR CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Objectives. Inhaled beta-2 agonists raise heart rate, systolic blood p ressure and contractility, all of which cause an increase in oxygen co nsumption of the heart. We performed a study on the influence of inhal ed salbutamol on myocardial ischaemia, rhythm, and heart rate variabil ity as assessed by Holter monitoring of 24 patients with coronary arte ry disease (CAD) and clinically stable asthma or chronic obstructive p ulmonary disease (COPD). Design. In hospital the patients received 0.2 mg (hour 1), 0.4 mg (hour 6), 0.8 mg (hour 13) of salbutamol with a m etered-dose inhaler and a spacer, and 5 mg (hour 25) with a nebulizer; symptoms, peak expiratory flow (PEF), 30-h Holter monitoring, and blo od pressure (BP) were recorded. The study parameters were compared for the hour preceding and following each dose of salbutamol. Results, No cardiac symptoms were associated with salbutamol inhalation. PEF incr eased after all doses (P < 0.005). A dose of 0.2 mg salbutamol induced no changes in heart rate, whereas dose of 0.4 mg increased heart rate from a mean of 75 +/- 13 to 79 +/- 14 beats min(-1) (P < 0.005), and a dose of 0.8 mg from 76 +/- 14 to 78 +/- 15 beats min(-1) (P < 0.05). No changes in systolic BP appeared after any dose of salbutamol. The diastolic BP was lowered after 0.8 mg of salbutamol from 86 +/- 12 to 82 +/- 10 mmHg (P < 0.05). The 5 mg of nebulized drug provoked no sign ificant changes in heart rate or BP. Myocardial ischaemia, heart rate variability and ventricular arrhythmias remained unaltered with all do ses. Conclusions. The commonly used doses of inhaled or nebulized salb utamol induced no acute myocardial ischaemia, arrhythmias or changes i n heart rate variability in patients with CAD and clinically stable as thma or COPD.