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Page 4 of 26 Chen et al. Plast Aesthet Res 2023;10:24 https://dx.doi.org/10.20517/2347-9264.2022.136

Complication rates have been shown to be lower in patients who delay breast reconstruction until after
radiation is complete [35,36] . Though there is little consensus in the literature regarding the optimal timing of
autologous reconstruction following radiation therapy, the majority of surgeons report waiting for 4-6 or 7-
12 months after the end of radiation, with patient preference and desire to optimize aesthetic outcomes
being the primary drivers of the timing selected [37,38] . Notably, Baumann et al. found that among patients
receiving delayed abdominal free flap breast reconstruction, flap loss and reoperation rate was higher
following reconstruction within 12 months of completion of radiation therapy . At our institution, we
[39]
routinely delay breast reconstruction for at least 6-12 months after the last radiation treatment, depending
on the total radiation dosage, the patient’s symptoms, and the effects noted on physical examination.

Hormonal therapy
Anti-estrogen therapies used in the adjuvant treatment of hormone-sensitive breast cancers, most notably
tamoxifen, have been shown to be associated with venous thromboembolism [40-42] . However, results from
studies examining the effect of hormone therapy on flap thrombosis are conflicting [43-47] . Although there are
studies suggesting discontinuation of hormone therapy 2 to 4 weeks prior to breast reconstruction, there is
no consensus in the literature on whether cessation is necessary [44,46-50] . Until a more definitive conclusion is
reached, at our institution, we typically recommend holding hormone therapy for a period of 2 weeks before
and after surgery, given the low oncologic risk of short-term cessation.

Thromboprophylaxis
Administering antithrombotic agents as a prophylactic measure against microvascular thrombosis is a
common but non-standardized practice. Protocols for thromboprophylaxis are based largely on individual
surgeon preference and opinion, and thus vary widely with regard to agents, dosage, schedule, and duration.
In this section, we describe commonly used antithrombotic agents and present an overview of recent
evidence on thromboprophylaxis protocols as well as our own institution’s regimen.

Heparin
Heparin binds and enhances the activity of antithrombin III, which in turn inhibits the coagulation cascade
and effectively blocks clot formation and growth. Although animal studies have demonstrated improvement
in microvascular thrombosis rates with heparin, clinical findings have been conflicting [51,52] . Lighthall et al.
and Zhou et al. found no significant differences in flap failure rates between patients with postoperative
heparin and patients with no postoperative anticoagulants [53,54] . Multiple studies have also found no
significant differences in microvascular thrombosis rates between cases performed with and without
intraoperative heparin [25,55,56] . However, an earlier study by Kroll et al. found that free flap patients dosed
with postoperative heparin had lower pedicle thrombosis rates and a trend toward lower flap loss compared
[56]
to patients with no postoperative anticoagulant agents .

Aspirin
Aspirin inhibits the production of thromboxane A2 by platelets, which prevents further platelet activation
and aggregation. Similar to heparin, the effectiveness of aspirin for flap thrombosis prevention is unclear
despite its widespread use. When used alone, aspirin has not been found to be effective for
[53]
thromboprophylaxis and may be associated with higher complication rates . Interestingly, Ashjian et al.
found in a retrospective review of 505 microvascular free flap patients that rates of microvascular
thrombosis and flap loss were equivalent between patients who received a postoperative 5-day daily regimen
of 325 mg of aspirin and patients who received 5,000 units of LMWH until ambulating .
[57]