Gated-SPECT in the Planning of Ischemia Guided PCI in STEMI Patients

Cardiovascular diseases (CVDs) are the leading cause of death globally.
According to WHO:
- An estimated 17.9 million people died from CVDs in 2019, representing 32% of all global deaths.
- Of these deaths, 85% were due to heart attack and stroke. Over three quarters of CVD deaths take place in low- and middle-income countries.
- Out of the 17 million premature deaths (under the age of 70) due to noncommunicable diseases in 2019, 38% were caused by CVDs.
- Most cardiovascular diseases can be prevented by addressing behavioral risk factors such as tobacco use, unhealthy diet and obesity, physical inactivity and harmful use of alcohol.
- It is important to detect cardiovascular disease as early as possible so that management with counselling and medicines can begin.

Among CDV - Ischemic heart disease (IHD) represents the largest share of morbidity and mortality globally. Also referred to as coronary artery disease (CAD) and atherosclerotic cardiovascular disease (ACD), IHD manifests clinically as myocardial infarction and ischemic cardiomyopathy.
The evaluation and management of ischemic heart disease has evolved significantly over the past decade. In particular, several clinical trials have documented the benefits of revascularization in patients with acute ischemic syndromes as well as the efficacy of medical therapy, including lifestyle modification in patients with stable coronary disease.
A fundamental premise in establishing new listing criteria for IHD mortality, morbidity and disability is the linking of anatomic or structural evidence of coronary heart disease (CHD) with both functional impairment and severe anginal symptoms. Because many patients with IHD are unable to exercise, standard stress electrocardiographic criteria for ischemia (the sole determinant of objective ischemia assessment in past years) have been expanded significantly to encompass non-exercise modalities (including nuclear imaging and echocardiography provoked by pharmacologic vasodilator stress) to assess the presence of severe inducible ischemia.

Primary percutaneous coronary intervention (PPCI) is the standard of care for ST-segment elevation myocardial infarction (STEMI), when performed by experienced groups in a timely manner. Although initial observational studies have shown conflicting results, evidence from four randomized controlled trials suggests that a post-primary percutaneous intervention (PPCI) strategy of staged PCI of the non-culprit vessel(s) is beneficial and safe in STEMI patients. Importantly, for this application, issues related to the evaluation of ischemia in the STEMI patient with multivessel coronary artery disease (CAD) focusing on PCI in the non-culprit lesion have not been fully addressed. When considering that 40-70% of STEMI patients have multivessel disease, alternative approaches for post-PPCI non-culprit lesion intervention need to be considered. The current application proposes a primary objective of applying gated-SPECT MPI as a guide to post-PPCI non-culprit coronary lesion intervention as compared to standard approaches which use post-PPCI intervention of all non-culprit lesions (based on anatomy alone).

We performed an international, randomized, non-inferiority trial comparing ischemia-guided non-culprit vessel angioplasty to routine non-culprit vessel angioplasty, following primary PCI for STEMI. The Ischemia-guided versus routine non-culprit vessel angioplasty for patients with ST segment elevation myocardial infarction and multi-vessel disease - the IAEA SPECT STEMI trial - Clinical trial registration number: CTRI/2018/08/015384

In the ischemia-guided arm, non-culprit PCI was performed if patients were symptomatic or had a positive stress myocardial perfusion imaging (MPI). In the routine non-culprit vessel PCI arm, all non-culprit vessels with angiographically significant lesions were treated within 6 weeks of randomization. The primary outcome was the difference in percent ischemic myocardium at follow-up stress MPI between the two arms. All MPI images were processed and analyzed at a central core lab, blinded to treatment allocation.

The hypothesis : "A strategy of ischemia-guided non-culprit vessel PCI is non-inferior to a routine non-culprit vessel PCI" was proved, thus helping to establish the value of gated-SPECT MPI protocol with pharmacological stress to guide efficacious multivessel PCI in STEMI patients.

This CRP contributes to achieve the SDG goal 3.4, by 2013 reduce by 30% the premature mortality due to NCDs. Which is in line with the objective of programme 2.2. of Supporting MS to address their health needs related to the prevention, diagnosis and treatment using radiation medicine.