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Tongxinluo Capsule Increases Coronary Plaque Fibrous Cap Thickness Over 12 Months
In patients with acute coronary syndrome, adding Tongxinluo capsule to standard statin therapy produced a meaningfully greater increase in minimum fibrous cap thickness compared to placebo at 12 months (115.0 µm vs. 80.0 µm, P < 0.001), a structural change associated with reduced plaque vulnerability. The result is encouraging as a mechanistic signal, though the trial was not powered to detect differences in hard cardiovascular outcomes.
What Was Studied
The trial investigated whether the traditional Chinese medicine preparation Tongxinluo capsule could enhance coronary plaque stability — specifically by thickening the fibrous cap of high-risk lesions — in patients already receiving guideline-directed therapy including statins. Thin-cap fibroatheroma is a well-established precursor of plaque rupture and acute coronary events, making fibrous cap thickness a clinically meaningful imaging surrogate.
How It Was Studied
TXL-CAP was a multicenter, randomized, double-blind, placebo-controlled trial registered in the Chinese clinical trials registry (ChiCTR1900025842). Eligible patients had a confirmed thin-cap lipid-rich coronary plaque identified by optical coherence tomography (OCT) in the setting of acute coronary syndrome, and were allocated 1:1 to receive either Tongxinluo capsule or matched placebo on top of standard care for 12 months. A total of 220 patients were recruited and randomized across participating centers. OCT-based plaque imaging was performed at baseline and again at 12 months, allowing direct comparison of structural plaque characteristics within the same lesion over time.
What Was Observed
- Fibrous cap thickness increased substantially more in the Tongxinluo group. At 12 months, minimum fibrous cap thickness was greater in the treatment arm than in the placebo arm (115.0 µm vs. 80.0 µm, P < 0.001), with the net change from baseline also significantly larger in the Tongxinluo group (increase of 61.2 µm vs. 33.7 µm, P = 0.002), indicating approximately twice the structural thickening over the study period.
- Lipid arc, a marker of plaque lipid burden, was more substantially reduced with Tongxinluo. The maximum lipid arc decreased by 38.4° in the treatment group compared with only 8.1° in the placebo group (P = 0.007), suggesting a meaningful reduction in the size of the necrotic lipid core — a key determinant of plaque instability.
- Angina symptom burden improved to a greater degree in treated patients. Tongxinluo recipients showed greater improvements than placebo recipients on both the Seattle Angina Questionnaire score and Canadian Cardiovascular Society grading, indicating a patient-reported as well as clinician-assessed symptomatic benefit.
- No significant difference in cardiovascular events was detected. The trial did not demonstrate a reduction in hard clinical endpoints at 12 months, though the study was not specifically designed or powered to assess event rates as a primary outcome.
Why This Matters
Stabilization of vulnerable coronary plaques is a central therapeutic goal in atherosclerosis research, and validated imaging surrogates such as fibrous cap thickness measured by OCT are increasingly accepted in mechanistic trials. This study provides the first randomized, controlled OCT-based evidence that Tongxinluo may augment plaque stabilization beyond what statins alone achieve, adding a quantitative structural dimension to prior observational and experimental data on this compound. The findings open a pathway for larger, event-driven trials to determine whether these imaging changes translate into clinical benefit.
How to Read This Result
While the OCT endpoints are objectively measured and the trial design is rigorous, the study was conducted in a single country, the 12-month follow-up limits conclusions about durability and longer-term outcomes, and the absence of a cardiovascular event benefit means the clinical translation of the structural changes remains to be established.
Limitations
The abstract does not explicitly report study limitations.