Prediction of outcome by 82Rb PET/CT in patients with ischemia and nonobstructive coronary arteries

doi:10.1007/s12350-022-03144-9

Journal of Nuclear Cardiology

Volume 30, Issue 3, June 2023, Pages 1110-1117

https://doi.org/10.1007/s12350-022-03144-9 Get rights and content

Abstract

Background

The purpose of this study was to assess the prognostic value of cardiac ⁸²Rb positron emission tomography (PET)/computed tomography (CT) imaging in patients with myocardial ischemia of nonobstructive coronary arteries (INOCA).

Methods

We retrospectively evaluated 311 INOCA patients who underwent rest stress ⁸²Rb PET/CT. Cardiac end points were cardiac death, myocardial infarction, or late coronary revascularization. A parametric survival model was also used to identify how the variables influenced time to event.

Results

During a median follow-up of 37 months (range 6–108), 23 (7%) cardiac events occurred. In patients with events total perfusion defect (TPD) was higher and myocardial flow reserve (MFR) lower compared to those without events (both P < .001). At multivariable Cox analysis, increased TPD (i.e., ≥ 5%) and reduced MFR (i.e., < 2) were predictors of events (both P < .001). At Weibull survival analysis, the highest probability of cardiac events and risk acceleration were observed in patients with both increased TPD and reduced MFR. Annualized event rate was higher in patients with reduced MFR compared to those with preserved MFR (P < .001).

Conclusion

In patients with INOCA, the combined evaluation of myocardial perfusion and coronary vascular function by ⁸²Rb PET/CT is able to identify those at higher risk of cardiac events.

Introduction

In patients with suspected coronary artery disease (CAD), the diagnostic work up is based on the detection of hemodynamically relevant stenosis.¹ However, up to 40% of invasive coronary angiography performed in patients with signs and symptoms of myocardial ischemia will be reported as nonobstructive CAD.² Myocardial ischemia of nonobstructive coronary arteries (INOCA) is a clinical entity associated with unfavorable prognosis, in particular in patients with alterations of myocardial perfusion.³^,⁴ Despite the physiologic mechanisms associated with INOCA remain to be elucidated, there is an increasing evidence that coronary microvascular dysfunction plays an important role.⁵ Radionuclide myocardial perfusion imaging is able to identify patients with abnormal perfusion at higher risk.⁶ Cardiac positron emission tomography (PET)/computed tomography (CT) is the gold standard for non-invasive evaluation of myocardial perfusion and coronary vascular function, integrated by the evaluation of coronary atherosclerotic burden. The extent of coronary calcification and presence of coronary vascular dysfunction are associated with an increased risk of adverse cardiac events in patients with suspected CAD.⁷ Combined evaluation of coronary artery calcium (CAC) score, myocardial perfusion, and myocardial flow reserve (MFR) is able to identify the high-risk patients.⁸^,⁹ However, the prognostic value of this approach has not been tested in patients with INOCA, in which the identification of coronary microvascular dysfunction might enhance risk stratification and patients’ management. The purpose of this study was to assess the prognostic value of cardiac ⁸²Rb PET/CT imaging in patients with INOCA.

Section snippets

Patients

We retrospectively evaluated 335 INOCA patients who underwent rest stress ⁸²Rb PET/CT between March 2012 and March 2016. INOCA was defined according to the evidence of symptoms and/or signs of ischemia, coronary risk profiles, and ECG findings in patients without significant CAD (≥ 50%) at invasive coronary angiography.¹⁰^,¹¹ For each patient, the presence of coronary risk factors was noted. This study complies with the declaration of Helsinki. The review committee of our institution approved

Patients characteristics

Follow-up data were not available in 24 (7%) of the 335 patients enrolled, leaving 311 subjects for the analysis. The median follow-up was 37 months (range 6–108). No patients experienced early (< 3 months) coronary revascularization procedures. During the follow-up, 23 events occurred (7% cumulative event rate, with an annual event rate of 1.1% person-years). The events were cardiac death in 2 (9%) patients, nonfatal myocardial infarction in 10 (43%), and coronary revascularization in 11 (48%)

Discussion

To our knowledge, this is the first study examining the prognostic value of cardiac PET/CT imaging in patients with INOCA. From our data it emerged that the combination of regional coronary myocardial perfusion and vascular function is able to predict the occurrence of events in patients without obstructive CAD at coronary angiography.

The presence of signs and symptoms of myocardial ischemia in patients with normal or near normal coronary arteries has been defined as INOCA.¹⁰ Previous studies

New knowledge gained

Our study adds new information about the potential role of cardiac PET/CT in the evaluation of patients with INOCA. The identification of subjects at higher risk of future cardiac events in this population is still challenging and myocardial perfusion imaging by ⁸²Rb PET/CT may contribute to selecting those candidates to more close therapeutic strategies.

Conclusion

In patients with INOCA, the combined evaluation of myocardial perfusion and coronary vascular function by ⁸²Rb PET/CT imaging is able to identify patients at higher risk of future cardiac events. Patients with myocardial perfusion abnormalities and impaired MFR are at higher risk of future cardiac events, suggesting that this combined evaluation may enhance risk stratification in patients with INOCA.

Disclosure

Emilia Zampella, Teresa Mannarino, Adriana D’Antonio, Roberta Assante, Valeria Gaudieri, Pietro Buongiorno, Mariarosaria Panico, Valeria Cantoni, Roberta Green, Carmela Nappi, Parthiban Arumugam, Mario Petretta, and Alberto Cuocolo, declare that they have no financial conflicts of interest. Wanda Acampa is consultant of D-Spectrum.

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Original ArticlePrediction of outcome by 82Rb PET/CT in patients with ischemia and nonobstructive coronary arteries

Abstract

Background

Methods

Results

Conclusion

Introduction

Section snippets

Patients

Patients characteristics

Discussion

New knowledge gained

Conclusion

Disclosure

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

J Nucl Cardiol

J Am Coll Cardiol

Atherosclerosis

Int J Cardiol

J Nucl Cardiol

J Nucl Cardiol

Am J Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Nucl Cardiol

Eur Heart J Cardiovasc Imaging

Low diagnostic yield of elective coronary angiography

N Engl J Med

Original Article
Prediction of outcome by ⁸²Rb PET/CT in patients with ischemia and nonobstructive coronary arteries