Prognostic significance of ischaemic electrocardiographic changes during stress testing in patients with normal nuclear myocardial perfusion imaging

Objectives: To evaluate cardiovascular outcomes in patients with normal nuclear myocardial perfusion imaging, but ischaemic electrocardiogram changes during pharmacological or exercise stress tests. Methods: The retrospective study was conducted at the Aga Khan University Hospital, Karachi, and comprised data of patients who underwent either pharmacological or exercise stress myocardial perfusion scan and had a normal scan with ischaemic electrocardiogram changes between January 2013 and December 2014. All cardiac events, including angina, myocardial infarction, heart failure, coronary revascularisation and cardiac death, as well as non-cardiac deaths were noted. Data was analysed using STATA 14.2. Results: Of the 2770 patients whose data was initially checked, 296(10.6%) developed ischaemic electrocardiogram changes during the stress test but had normal myocardial perfusion scan. Of them, 181(61%) patients were male, and the overall mean age was 62±15 years. Follow-up data was available for 280(94.5%) of these patients, with a mean follow-up of 48±7 months. Of these patients, 8(2.8%) died, and 1(0.3%) of them died due to inferior wall myocardial infarction. Myocardial infarction was found in 2(0.7%) patients, and 1(0.3%) patient was hospitalised with heart failure. Also, 12(4.3%) patients underwent revascularization for stable angina, 9(3.2%) underwent percutaneous transluminal coronary angioplasty, and 3(1.07%) needed coronary artery bypass grafting. Conclusion: Ischaemic electrocardiographic changes during stress testing in patients with normal myocardial perfusion scan were not associated with adverse outcomes, and the risk of cardiovascular events was relatively low for an intermediate follow-up period.