Morphological supply and dynamic reserve mismatch in coronary chronic total occlusion: a multimodality imaging study
H Kawai, A Yamada, M Sarai, M Ishikawa, H Ota, T Muramatsu, M Yanase, H IzawaAbstract
Background
In coronary chronic total occlusion (CTO), revascularization is often guided by angiographic collaterals and relative perfusion. However, whether these indices reflect actual hemodynamic reserve remains unclear.
Purpose
We aimed to investigate the relationship between morphological supply and dynamic reserve, with the latter defined by an O2 pulse plateau during cardiopulmonary exercise testing (CPET) as a marker of global hemodynamic limitation.
Methods
We prospectively included 38 CTO patients (33 men; median age, 71.0 [IQR, 62.8–77.3] years) scheduled for PCI. Patients underwent CPET, dobutamine stress echocardiography (DSE), and adenosine myocardial perfusion SPECT (MPS). O2 pulse, defined as VO2 divided by heart rate, represents the oxygen volume extracted per heartbeat; a plateau in this parameter reflects a stroke volume limitation induced by extensive ischemia. Contractile response in the CTO territory during DSE was categorized into five patterns: normal, sustained improvement, worsening, biphasic, or no change. Patients were stratified by O2 pulse plateau status: the ischemia (+) group (n=12) vs. the (-) group (n=26).
Results
Resting LVEF was preserved and comparable between groups (p=0.22). The incidence of a biphasic wall motion pattern on DSE, induced by high-dose dobutamine and indicating local mechanical limitation, was significantly more frequent in the O2 pulse plateau (+) group than in the (-) group (83.3% vs. 46.2%, p=0.03); this finding was consistent with global hemodynamic limitation. Conversely, morphological and relative perfusion parameters showed possible discordance; neither Rentrop collateral grade (p=0.47) nor SPECT-ischemia (58.3% vs. 73.1%, p=0.37) differed significantly between groups.
Conclusion
While angiographic and pharmacological perfusion metrics primarily provide anatomical information on the supply side, dynamic stress testing (CPET and DSE) may provide clinically relevant insights into hemodynamic and contractile limitations under high-demand conditions in CTO; these parameters do not necessarily coincide.Functional Reserve vs. Supply in CTOFor image description, please refer to the figure legend and surrounding text.Patient Characteristics and Imaging FindingsFor image description, please refer to the figure legend and surrounding text.