2. Gillmore JD, Maurer MS, Falk RH, et al. Nonbiopsy diagnosis of cardiac transthyretin amyloidosis. Circulation 2016;133:2404–12. 3. Gagliardi C, Tabachhi E, Bonfiglioli R, et al. Does the etiology of cardiac amyloidosis determine the myocardial uptake of [18F]-NaF PET/CT? J Nucl Cardiol 2016 Mar 14 [E-pub ahead of print]. A Bridging Protocol in High-Thrombotic Risk Mechanical Valve Bearers Undergoing Surgery or Invasive Procedures Periprocedural bridging in high-thrombotic-risk me- chanical heart valve (htr-MHV) bearers has not been definitively addressed (1–3). In a previous study (4), we assessed the effectiveness and safety of a bridging protocol with an intermediate dose of low- molecular-weight heparins (LMWHs), but definite conclusions for htr-MHV patients could not be drawn. To this end, we performed a hybrid registry-cohort study in htr-MHV bearers, defined as a prosthesis in the mitral position or in the aortic position associated with risk factors (2). Low-risk aortic prostheses were excluded. The protocol (70 anti-factor Xa U/kg enoxaparin or nadroparin twice daily) was designed to satisfy the closest requirement for a per-kilogram commercially available prefilled syringe; thus, an 80-kg patient would receive 6000 International Units (IU) of enox- aparin twice daily or 5700 IU of nadroparin twice daily. The protocol, detailed elsewhere (4), is outlined in Figure 1. It had to be strictly followed, but some flexibility was allowed, for example, LMWH could be initiated at day À5 in case international normalized ratio (INR) was below therapeutic range; or the pro- cedure could be postponed if day 0 INR was >1.5; or post-intervention, LMWH could be resumed 12 or 24 h according to hemostasis adequacy. The primary efficacy and safety outcomes were the incidence of thrombotic and major bleeding events (4) during a follow-up of 90 and 30 days, respectively. A sample size of 360 cases was set as appropriate based on a mean incidence of com- posite events on htr-MHV of 4.4% in the previous study (4). Overall, 385 consecutive procedures were re- ported, with 366 procedures included in the final analysis. Mean age was 69 years old, and 47.8% were female. Body weight ranged from 35 to 130 kg (median 74 kg). The most common vitamin K antag- onists and LMWH used were warfarin (85%) and enoxaparin (72%). MHV in mitral and aortic positions were almost evenly distributed (43% and 40%, respectively), whereas 17% of the patients had double-valve replacements. The most common MHVs were bileaflet valves (86%), followed by tilting-disk (13%) and caged-ball valves (1%). Overall, there were 136 and 230 high- and low-bleeding risk pro- cedures, respectively. No procedure was postponed because of an INR >1.5 at day 0. One arterial thrombotic event (0.27%; 95% confi- dence interval [CI]: 1.01 to 1.69) was recorded during follow-up, and no clinical signs of prosthesis dysfunction were reported. Major bleeding, reported in 24 cases (6.6%; 95% CI: 4.4 to 9.6), was significantly more frequent in patients undergoing high-bleeding-risk surgery (11.8% vs. 3.5%, respec- tively; odds ratio: 3.7; 95% CI: 1.5 to 8.9; p ¼ 0.004). FIGURE 1 Periprocedural Bridging Protocol Days LMWH LMWH Surgery No VKA Outpatient In or Outpatient Depending on Procedure VKA at usual+50% boost dose VKA at usual dose –5 –3 –1 +1 12hrs +2 +3 +6 0 INR INR INR INR ¼ international normalized ratio; LMWH ¼ low-molecular-weight heparins; VKA ¼ vitamin K antagonist. Letters JACC VOL. 68, NO. 24, 2016 DECEMBER 20, 2016:2710 – 8 2714