Safety and tolerability of adenosine stress MPI in patients with asthma or chronic obstructive airways disease

Abstract

Listen

Translate article

Background: Vasodilator stress is traditionally contraindicated in patients with asthma or chronic obstructive airways disease (A/COAD). However, recent evidence suggests that adenosine is safe in well-controlled disease. We conducted a systematic review of the safety and tolerability of adenosine stress in patients with A/COAD. Methods: 124 patients (46% asthma, 54% COAD) were identified from 1261 consecutive subjects referred for myocardial perfusion SPECT imaging. Patients were given adenosine if asthma only mild or moderate, no admission for an exacerbation in last year, no current steroid therapy, documented FEV1 or peak expiratory flow ≥70% predicted, no wheeze on auscultation. An inhaled short-acting beta-2-agonist (salbutamol, 200 mcg) was administered and adenosine titrated starting at 70 mcg/kg/min for 1 minute, increasing to 100 mcg/kg/min for another 1 minute up to the maximal dose of 140 mcg/kg/min for 4 minutes. Radiotracer was injected 2 minutes before termination of the adenosine infusion. Adherence to protocol, patient symptoms and complications were compared with a control group (non-A/COAD) matched for age, sex and clinical indications. Results: Of 124 patients, 72 (58%) were suitable for adenosine stress. Adenosine was combined with exercise in the majority of cases (86.1%). The protocol was completed successfully in a similar proportion of tests (100% control vs. 97.2% A/COAD, p=0.5). Symptoms were mostly minor and well tolerated, with dyspnoea reported more often in the A/COAD group (50% vs. 34% p=0.03). There were 4 cases of bronchospasm in the A/COAD group, all reverted shortly after discontinuation of adenosine (n=2) or administration of inhaled salbutamol. Aminophylline was not required. No other complications were reported. A similar proportion of studies showed reversible perfusion abnormalities in both groups (42% A/COAD vs. 50% control, p=0.3). Conclusion: A titrated adenosine protocol with prophylactic use of an inhaled beta-2-agonist is a safe procedure in patients with history of mild, well-controlled asthma or COAD undergoing stress myocardial perfusion imaging.