\begin{table}
\centering
\caption{Predictors of Late-Acquired Stent Malapposition}
\label{table_4}
\begin{tabular}{lccc}
\hline
 & Late-Acquired Stent Malapposition Lesions (n=54) & No Late-Acquired Stent Malapposition Lesions (n=302) & P Value \\
\hline
\multicolumn{4}{l}{Follow-up optical coherence tomography} \\
Time intervals after index procedure, days & 173 $\pm$ 43 & 175 $\pm$ 63 & 0.841 \\
Late-acquired malapposed struts, \% & 3.8 $\pm$ 4.5 & 0 & --- \\
Maximum late-acquired stent malapposition cross-sectional area, mm$^2$ & 0.95 $\pm$ 0.90 & 0 & --- \\
Late-acquired stent malapposition volume, mm$^3$ & 2.06 $\pm$ 3.24 & 0 & --- \\
Late-acquired stent malapposition volume, \% (of stent volume) & 1.7 $\pm$ 3.1 & 0 & --- \\
Late-acquired stent malapposition within stent body & 33 (61\%) & 0 & --- \\
Acute coronary syndrome* & 18 (33\%) & 88 (30\%) & 0.586 \\
Dyslipidemia* & 34 (63\%) & 155 (52\%) & 0.144 \\
B2- or C-type lesion & 24 (44\%) & 132 (44\%) & 0.745 \\
Baseline diameter stenosis, \% & 69 $\pm$ 20 & 65 $\pm$ 14 & 0.299 \\
Stent diameter, mm & 3.22 $\pm$ 0.37 & 3.14 $\pm$ 0.36 & 0.178 \\
Stent length, mm & 19.0 $\pm$ 5.4 & 18.9 $\pm$ 5.1 & 0.955 \\
\multicolumn{4}{l}{Poststent optical coherence tomography} \\
Plaque/thrombus prolapse & 38 (70\%) & 128 (42\%) & $<$0.001 \\
\hline
\end{tabular}
\end{table}

*Analyzed in patient level.

implantation. Neointimal healing reduces the volume of acute stent malapposition with many acute stent malapposition struts becoming completely integrated into the vessel wall. However, cases of acute stent malapposition with a large volume or acute stent malapposition located within the edges of the stent were not resolved in most cases. Thus, acute stent malapposition volume and location within stent edges were identified as independent predictors of late-persistent stent malapposition. Our results indicate that an acute stent malapposition with a larger volume or area is more likely to persist at follow-up examinations, which is consistent with findings from previous studies \cite{4,6,8}. Late-persistent stent malappositions could be differentiated from resolved acute stent malapposition by an acute stent malapposition area $>$1.2 mm$^2$ according to an IVUS study \cite{6}. A strut-to-vessel distance $\geq$260 $\mu$m on poststent OCT images was suggested as a cut-off value for resolved acute stent malapposition \cite{18}. A volume of acute stent malapposition $>$2.56 mm$^3$ best separated late-persistent stent malapposition lesions from resolved acute stent malapposition lesions in the present study.

\section{Late-Acquired Stent Malapposition}

The presence of a plaque/thrombus protrusion, which was most often (75\%) located within the stent body on poststent IVUS images, was reported to be a predictor of late-acquired stent malapposition \cite{6}. Thus, it was suggested that plaque/

\begin{table}
\centering
\caption{Incidences of Clinical Events and Duration of Dual Antiplatelet Therapy During Follow-up}
\label{table_5}
\begin{tabular}{lccccc}
\hline
 & Overall Patients (N=351) & Both Late-Persistent and Late-Acquired Stent Malapposition (n=23) & Late-Acquired Stent Malapposition Alone (n=31) & Late-Persistent Stent Malapposition Alone (n=45) & No Stent Malapposition (n=252) \\
\hline
Follow-up duration after PCI, mo & 28.6 $\pm$ 10.3 & 24.3 $\pm$ 4.3 & 27.7 $\pm$ 10.0 & 28.4 $\pm$ 9.2 & 29.1 $\pm$ 10.8 \\
Follow-up duration after follow-up OCT, mo & 22.8 $\pm$ 10.4 & 18.4 $\pm$ 4.4 & 22.0 $\pm$ 10.4 & 22.6 $\pm$ 8.9 & 23.3 $\pm$ 10.9 \\
Composite of clinical events & 10 (2.9\%) & 0 (0\%) & 1 (3.2\%) & 1 (2.2\%) & 8 (3.2\%) \\
Cardiovascular death & 1 (0.3\%) & 0 (0\%) & 0 (0\%) & 0 (0\%) & 1 (0.4\%) \\
Nonfatal myocardial infarction & 1 (0.3\%) & 0 (0\%) & 0 (0\%) & 0 (0\%) & 1 (0.4\%) \\
Stent thrombosis & 0 (0\%) & 0 (0\%) & 0 (0\%) & 0 (0\%) & 0 (0\%) \\
Target lesion revascularization & 8 (2.3\%) & 0 (0\%) & 1 (3.2\%) & 1 (2.2\%) & 6 (2.4\%) \\
Duration of dual antiplatelet therapy, mo & 14.2 $\pm$ 8.2 & 11.9 $\pm$ 5.3 & 15.5 $\pm$ 6.4 & 13.8 $\pm$ 7.1 & 14.3 $\pm$ 8.7 \\
At least 12 mo of dual antiplatelet therapy & 262 (75\%) & 15 (65\%) & 27 (87\%) & 36 (80\%) & 184 (73\%) \\
\hline
\end{tabular}
\end{table}

OCT indicates optical coherence tomography; and PCI, percutaneous coronary intervention.