Transradial vs Transfemoral Coronary Intervention for AMI
Several clinical studies have compared the results of TRI and TFI in patients with AMI; however, most of these reports excluded shock cases. Patients with AMI complicated by cardiogenic shock have a worse clinical course, and shock has been reported to predict mortality. In the real world, PCI has been performed even in patients with AMI complicated by cardiogenic shock, although the influence of access-site remains unclear. Therefore, in the present study, we compared the clinical results of TRI and TFI in AMI patients who had cardiogenic shock and underwent emergency PCI.
Multiple potent antiplatelet drugs are routinely given to patients with AMI; therefore, it is not surprising that bleeding and vascular complications often develop in patients who undergo TFI. Compared with the femoral artery, the radial artery is more superficial, surrounded by less subcutaneous tissue, and has a smaller diameter. A small diameter is an important predictive factor for maintaining homeostasis of the access site after removal of the sheath, even when anticoagulants are given systemically. Several studies have reported that both reductions in bleeding and vascular complications are associated with improved clinical outcomes, especially in AMI patients. In this study, the incidence of major bleeding and vascular complications was higher than in previous studies in AMI patients without cardiogenic shock; however, the incidence of these complications in the present study was similar to previous reports where AMI was complicated by cardiogenic shock. Furthermore, compared with TFI, the TRI group was associated with significantly less major bleeding and vascular complications within 30 days and 1 year.
When major bleeding complications develop, it is desirable to correct them by transfusion. This is especially important in patients with cardiogenic shock. However, blood transfusion itself increases the risk of mortality in AMI patients. This might be due in part to alterations in erythrocyte nitric oxide biology in transfused blood that leads to initial vasoconstriction, platelet aggregation, and ineffective oxygen transportation. In addition, hemorrhage as well as blood transfusion by themselves can cause inflammation. Thus, it is important that TRI reduces the need for blood transfusion and its associated mortality risk.
IABP is the mechanical support device currently used most widely for the treatment of cardiogenic shock. The use of the IABP for cardiogenic shock is recommended in both American College of Cardiology/American Heart Association (class IB evidence) and European Society of Cardiology guidelines (class IC evidence). However, if IABP is used, there is a further risk of bleeding complications. Additionally, PCPS is also used as a support device in cases of cardiogenic shock, and no significant difference was apparent between the two groups in PCPS use ( Table 2 ). If PCPS is used, the risk of bleeding complications will obviously increase. In cases that require PCPS, IABP is often used at the same time, and the risk of bleeding complications should increase even further. TRI does not reduce the added bleeding risk from the IABP and/or PCPS; however, TRI is able to reduce the total risk of access-site bleeding complications in the patients who received IABP and/or PCPS. In addition, when PCPS and IABP are used together, both femoral arteries are needed to insert these devices, therefore, TRI is more useful in this situation.
Moreover, as in the RACE study conducted in North Carolina, if AMI patients who have not yet arrived at a PCI emergency center cannot immediately undergo PCI, fibrinolytic therapy may be carried out prior to transport. Since there is also a further risk of bleeding complications in such cases, TRI is recommended under these circumstances as well.
Cardiogenic shock has been reported to be an independent predictor of MACCE and mortality. In the present study, the overall rates of MACCE and mortality were similar to those in previous studies in patients with AMI complicated by cardiogenic shock. Both the rates of MACCE and mortality within 30 days and 1 year were higher in the TFI group than in the TRI group; however, these differences were not significant. The development of bleeding complications is an independent risk factor for both MACCE and in-hospital mortality. Although we observed less bleeding in the TRI group, no difference in mortality within 1 month was observed between the two groups. Since AMI complicated by cardiogenic shock has a high in-hospital mortality, it is possible that a difference in mortality due to bleeding complications was masked by the effect of cardiogenic shock on the mortality rate in both groups.
To achieve rapid revascularization, TFI is still used for PCI in patients with AMI. The learning curve for TRI is greater than for TFI, and it has been reported that the rate of access-site crossover is higher in TRI. This is especially true in shock cases, when it is difficult to palpate a pulse in the radial artery. Door-to-balloon times have been shown to be an independent predictor of mortality. In this study, no significant difference was observed in the doorto-balloon time between TRI and TFI. In addition, the procedural success rate was 95.3% in the entire cohort. This success rate is similar to previous studies of AMI that either excluded or included cardiogenic shock cases. Furthermore, in the present study, the procedural success rate was similar between the TRI and TFI groups. According to a previous report, a higher success rate and skill in PCI can be acquired by the systematic use of TRI. Therefore, we suggest that TRI is able to be used as the primary access site in most AMI patients.
Moreover, in the RIVAL trial, it was suggested that the benefits of TRI over TFI include a higher level of experience and expertise by the operators performing TRI. Accordingly, PCI was performed largely with TRI by four very experienced operators at our center, and we believe this will lead to increased skill and experience.
In previous studies, TRI was shown to shorten the duration of hospitalization, improve quality of life, and reduce the cost of catheterization. However, in our study, no significant difference was found between the two groups in the length of hospital stay. The overall average length of hospital stay in our study was 35.6 days, and this prolonged duration of hospitalization was probably due to the fact that all patients enrolled in the study had cardiogenic shock.
This study did have some limitations that deserve consideration. First, our center generally performed PCI using TRI at the time this study was initiated. Since the operators were well trained in the use of TRI, it is possible that this training influenced the results. Therefore, it may be difficult to generalize these results to centers that do not perform TRI on a routine basis. Second, the access site for PCI was chosen by the operators; thus, some selection bias may have been possible. However, PCPS was used in the most severe cases, and no significant difference was apparent between the two groups. PCPS was used in more than 20% of the cases in the TRI group ( Table 2 ), and this indicates that operators did not avoid TRI based on the severity of the patient's condition. Finally, this was a retrospective analysis of a nonrandomized, single-center experience, and the sample size was relatively small. Thus, further prospective multicenter studies are needed to confirm our results.
Discussion
Several clinical studies have compared the results of TRI and TFI in patients with AMI; however, most of these reports excluded shock cases. Patients with AMI complicated by cardiogenic shock have a worse clinical course, and shock has been reported to predict mortality. In the real world, PCI has been performed even in patients with AMI complicated by cardiogenic shock, although the influence of access-site remains unclear. Therefore, in the present study, we compared the clinical results of TRI and TFI in AMI patients who had cardiogenic shock and underwent emergency PCI.
Major Bleeding and Vascular Complications Within 30 Days and 1 Year
Multiple potent antiplatelet drugs are routinely given to patients with AMI; therefore, it is not surprising that bleeding and vascular complications often develop in patients who undergo TFI. Compared with the femoral artery, the radial artery is more superficial, surrounded by less subcutaneous tissue, and has a smaller diameter. A small diameter is an important predictive factor for maintaining homeostasis of the access site after removal of the sheath, even when anticoagulants are given systemically. Several studies have reported that both reductions in bleeding and vascular complications are associated with improved clinical outcomes, especially in AMI patients. In this study, the incidence of major bleeding and vascular complications was higher than in previous studies in AMI patients without cardiogenic shock; however, the incidence of these complications in the present study was similar to previous reports where AMI was complicated by cardiogenic shock. Furthermore, compared with TFI, the TRI group was associated with significantly less major bleeding and vascular complications within 30 days and 1 year.
When major bleeding complications develop, it is desirable to correct them by transfusion. This is especially important in patients with cardiogenic shock. However, blood transfusion itself increases the risk of mortality in AMI patients. This might be due in part to alterations in erythrocyte nitric oxide biology in transfused blood that leads to initial vasoconstriction, platelet aggregation, and ineffective oxygen transportation. In addition, hemorrhage as well as blood transfusion by themselves can cause inflammation. Thus, it is important that TRI reduces the need for blood transfusion and its associated mortality risk.
IABP is the mechanical support device currently used most widely for the treatment of cardiogenic shock. The use of the IABP for cardiogenic shock is recommended in both American College of Cardiology/American Heart Association (class IB evidence) and European Society of Cardiology guidelines (class IC evidence). However, if IABP is used, there is a further risk of bleeding complications. Additionally, PCPS is also used as a support device in cases of cardiogenic shock, and no significant difference was apparent between the two groups in PCPS use ( Table 2 ). If PCPS is used, the risk of bleeding complications will obviously increase. In cases that require PCPS, IABP is often used at the same time, and the risk of bleeding complications should increase even further. TRI does not reduce the added bleeding risk from the IABP and/or PCPS; however, TRI is able to reduce the total risk of access-site bleeding complications in the patients who received IABP and/or PCPS. In addition, when PCPS and IABP are used together, both femoral arteries are needed to insert these devices, therefore, TRI is more useful in this situation.
Moreover, as in the RACE study conducted in North Carolina, if AMI patients who have not yet arrived at a PCI emergency center cannot immediately undergo PCI, fibrinolytic therapy may be carried out prior to transport. Since there is also a further risk of bleeding complications in such cases, TRI is recommended under these circumstances as well.
MACCE and All-cause Death Within 30 Days and 1 Year
Cardiogenic shock has been reported to be an independent predictor of MACCE and mortality. In the present study, the overall rates of MACCE and mortality were similar to those in previous studies in patients with AMI complicated by cardiogenic shock. Both the rates of MACCE and mortality within 30 days and 1 year were higher in the TFI group than in the TRI group; however, these differences were not significant. The development of bleeding complications is an independent risk factor for both MACCE and in-hospital mortality. Although we observed less bleeding in the TRI group, no difference in mortality within 1 month was observed between the two groups. Since AMI complicated by cardiogenic shock has a high in-hospital mortality, it is possible that a difference in mortality due to bleeding complications was masked by the effect of cardiogenic shock on the mortality rate in both groups.
Door-to-balloon Time and PCI Procedural Success
To achieve rapid revascularization, TFI is still used for PCI in patients with AMI. The learning curve for TRI is greater than for TFI, and it has been reported that the rate of access-site crossover is higher in TRI. This is especially true in shock cases, when it is difficult to palpate a pulse in the radial artery. Door-to-balloon times have been shown to be an independent predictor of mortality. In this study, no significant difference was observed in the doorto-balloon time between TRI and TFI. In addition, the procedural success rate was 95.3% in the entire cohort. This success rate is similar to previous studies of AMI that either excluded or included cardiogenic shock cases. Furthermore, in the present study, the procedural success rate was similar between the TRI and TFI groups. According to a previous report, a higher success rate and skill in PCI can be acquired by the systematic use of TRI. Therefore, we suggest that TRI is able to be used as the primary access site in most AMI patients.
Moreover, in the RIVAL trial, it was suggested that the benefits of TRI over TFI include a higher level of experience and expertise by the operators performing TRI. Accordingly, PCI was performed largely with TRI by four very experienced operators at our center, and we believe this will lead to increased skill and experience.
Length of Hospital Stay
In previous studies, TRI was shown to shorten the duration of hospitalization, improve quality of life, and reduce the cost of catheterization. However, in our study, no significant difference was found between the two groups in the length of hospital stay. The overall average length of hospital stay in our study was 35.6 days, and this prolonged duration of hospitalization was probably due to the fact that all patients enrolled in the study had cardiogenic shock.
Study Limitations
This study did have some limitations that deserve consideration. First, our center generally performed PCI using TRI at the time this study was initiated. Since the operators were well trained in the use of TRI, it is possible that this training influenced the results. Therefore, it may be difficult to generalize these results to centers that do not perform TRI on a routine basis. Second, the access site for PCI was chosen by the operators; thus, some selection bias may have been possible. However, PCPS was used in the most severe cases, and no significant difference was apparent between the two groups. PCPS was used in more than 20% of the cases in the TRI group ( Table 2 ), and this indicates that operators did not avoid TRI based on the severity of the patient's condition. Finally, this was a retrospective analysis of a nonrandomized, single-center experience, and the sample size was relatively small. Thus, further prospective multicenter studies are needed to confirm our results.