CT Coronary Angiography for Type 2 Myocardial Infarction

A Pilot Clinical Trial of CT Coronary Angiography for Patients With Suspected Type 2 Myocardial Infarction

This study is to explore whether a computed tomography (CT) scan of the heart arteries might improve the care of patients that have presented with a suspected Type 2 myocardial infarction (MI). The Investigators hope to demonstrate that these patients may be the ideal group of patients to benefit from cardiac CT scan imaging by; 1. confirming whether they have any disease in their heart arteries 2. demonstrating the severity of the heart artery disease 3. revealing an alternative cause for their presentation 4. avoiding the need for an invasive heart artery angiogram.

An increasing number of patients present to hospital with a heart attack (myocardial infarction, MI). Heart attacks can be caused by instability and narrowing in heart arteries (Type 1 MI) or strain on the heart (Type 2 MI). Type 2 MIs can be the result of other problems with the heart including inflammation and rhythm problems or other conditions such as infection or low blood count. Both Type 1 and Type 2 MI patients have increased risk of further problems following this presentation. Deciding whether a patient has suffered a Type 1 MI or a Type 2 MI can be very difficult leaving uncertainty for patients and health care staff. Often patients with Type 2 myocardial infarction are either referred for an invasive coronary angiogram (a procedure where dye is injected into the heart arteries directly) or have no further investigations. Invasive angiograms carry a small risk of complications including heart attack, stroke and, rarely, death. Cardiac CT scanning has emerged in the last 20 years as the first test usually performed to investigate patients that present with stable chest pain symptoms to the outpatient department. The role of cardiac CT in patients that present as an emergency with a suspected heart attack is not yet established. To date, there are no substantive data on the role of computed tomography coronary angiography (CTCA) in patients with known or suspected Type 2 MI. A pilot study is proposed to address the information gaps. The specific areas of uncertainty include feasibility of enrolling into an imaging trial during acute medical care, feasibility of randomisation (including compliance and cross-overs), incremental diagnostic value, safety (procedure and post-procedure) and healthcare resource utilisation. The study aims to address the gap in evidence highlighted by the recent European Society of Cardiology Guidelines for the management of acute coronary syndromes, 'evaluating diagnostic strategies to better classify patients according to their type of MI (Type 1 vs Type 2)'.

The primary outcome is a change in the primary diagnosis defined as a difference in the final diagnosis at discharge compared to the initial diagnosis prior to study recruitment. The primary outcome will therefore take account of the diagnostic effect of CTCA and any changes that might normally occur during standard care.

Referral to outpatient clinic or for additional cardiovascular test (including exercise tolerance testing, echocardiography, myocardial perfusion imaging, cardiac MRI)

EQ-5D-5L questionnaire. Reported as 5 digit code (Range 11111 - 55555) with higher numbers indicating worse quality of life and EQ visual analogue scale (Range 0-100) with higher numbers indicating better quality of life.

Inclusion Criteria: Patients with known or suspected Type 2 MI Exclusion Criteria: Unable to provide written informed consent Known severe coronary artery disease Previous PCI Previous CABG Severe renal dysfunction, defined as an eGFR <30 mL/min/1.73 m2 Tachycardia (>75bpm) refractory to heart rate control Pregnancy

Byrne RA, Rossello X, Coughlan JJ, Barbato E, Berry C, Chieffo A, Claeys MJ, Dan GA, Dweck MR, Galbraith M, Gilard M, Hinterbuchner L, Jankowska EA, Juni P, Kimura T, Kunadian V, Leosdottir M, Lorusso R, Pedretti RFE, Rigopoulos AG, Rubini Gimenez M, Thiele H, Vranckx P, Wassmann S, Wenger NK, Ibanez B; ESC Scientific Document Group. 2023 ESC Guidelines for the management of acute coronary syndromes. Eur Heart J Acute Cardiovasc Care. 2023 Sep 22:zuad107. doi: 10.1093/ehjacc/zuad107. Online ahead of print. No abstract available.