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Incidence of side effects of immunosuppressants commonly used in heart transplantation
Incidence of Side Effects of Immunosuppressants Commonly Used in Heart Transplantation L. Almenar, J. Rueda, A. Osa, M.A. Arnau, L. Martinez-Dolz, and M. Palencia
H
EART transplant (HT) is currently the treatment of choice in patients with severe heart disease in a poor clinical condition and not amenable to improvement with alternative therapies.1 These patients require chronic and sustained administration of immunosuppressive drugs to decrease the incidence and severity of graft rejection.2 In most centers, the immunosuppressive protocol used is the triple therapy with cyclosporine, azathioprine, and steroids. Because immune activity and the trend toward rejection are most marked in the first few months’ posttransplant, most regimens provide higher doses during this initial period, followed by gradual dose decrements until maintenance levels are reached. However, and despite the use of increasingly lower doses, the morbidity associated to immunosuppressive medication remains high.3– 6 The purpose of this study was to ascertain the frequency of side effects caused by the immunosuppressive drugs commonly used after HT, and the differences in their midand long-term incidence. MATERIALS AND METHODS Patients and Study Design Sixty-three consecutive HT patients subjected to routine follow-up in the cardiology outpatient clinic of our hospital were analyzed. There were 55 males and 8 females, with a mean age of 49 ⫾ 12 years (range 14 to 67 years). All patients were in a stable condition, with a time elapsed from transplant of more than 18 months. The disease leading to HT was idiopathic dilated cardiomyopathy (26 cases), ischemic heart disease (25 cases), valvular diseases (7 cases), and other conditions (7 cases). At the end of their routine follow-up visit, patients were administered a questionnaire to determine the side effects of immunosuppressive therapy. The questionnaire was always applied by the same physician. The answers were then analyzed to assess the overall incidence of each variable and the difference between the incidence rate of the effect before and after 5 years’ posttransplant.
Immunosuppressive Protocol The immunosuppressive protocol was the one routinely used in our center, and it consisted of cyclosporine (CyA) and azathioprine before surgery, followed by induction with OKT3 and maintenance with CyA, azathioprine, and steroids after transplant. The same protocol was given to all patients. Cyclosporine was given at doses appropriate to achieve levels ranging from 200 to 300 ng/mL in the first 6 months, and 100 to 200 ng/mL thereafter. The standard azathioprine dose was 2 mg/kg per
day, maintaining a WBC count above 4000/mm3. The steroid used was Deflazacort in all cases, at an initial dose of 1.2 mg/kg per day, followed by gradual decrements; 1 month after HT, the mean dose administered was 21 mg/d, as compared to 15 mg/d after one year. In our protocol, an attempt to discontinue Deflazacort is made. Drug discontinuation was achieved in 24 of the 63 patients included in the present study (38%).
Variables Analyzed A survey was made of the side effects of immunosuppression. The variables analyzed were vision loss, cataracts, cold hands and feet, gingival hypertrophy, impotence, nail mycosis, increased skin pigmentation or redness, disabling osteoporosis, hypertrichosis, and trembling of the hands (Table 1).
Statistical Analysis The variables analyzed were recorded as percentages. Comparisons were made using the chi-squared (with Yates’ continuity correction) and Fisher F tests (for small groups). A value of P ⱕ .05 was considered statistically significant.
RESULTS Overall Side Effects
The incidence of side effects attributable to immunosuppressive treatment is shown in Table 2. Diminished vision, recorded in almost 50% of cases, was the most common secondary effect. Of note is the high incidence of cataracts (up to 30%). Tremor was the most frequent neurological adverse effect (24%). In turn, skin reddening and hyperpigmentation occurred in 38% of cases, while gingival hyperplasia and hypertrichosis (both typical of CyA treatment) were recorded in 38% and 43% of patients, respectively. The incidence of cold hands and feet, disabling bone pain, and nail mycosis was less significant. Most patients studied had at least one side effect. Only 13% were free of effects. Side Effects According to Time Periods
Table 2 summarizes the incidence of side effects by time periods. An increased incidence of gingival hyperplasia can From the Department of Cardiology, La Fe University Hospital, Valencia, Spain. Address reprint requests to Luis Almenar, Clinical Cardiology Section, Dept of Cardiology, La Fe University Hospital, 46-020 Valencia, Spain.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0041-1345/99/$–see front matter PII S0041-1345(99)00444-3
Transplantation Proceedings, 31, 2519–2521 (1999)
2519
2520
ALEMENAR, RUEDA, OSA ET AL Table 1. Questionnaire
Cataracts: Has the ophthalmologist told you that you have cataracts? Cold hands and feet: Do your hands and feet easily become cold— unlike before transplant? Gingival hypertrophy: Do you notice inflammation of the gums? Impotence: Do you feel a lessened sex urge or erection problems? Compared to pretransplant situation? Nail mycosis: Do your nails break easily at the edges? Did the dermatologists say it’s a fungal infection? Increased skin pigmentation: Do you easily become red or tanned spontaneously or following minor exposure to sunlight? Disabling osteoporosis: Do you suffer bone pain that limits daily activities? Hypertrichosis: Do you notice an increase in hairiness? Trembling of the hands: Have you tremor in the fingers? Spread your hands to see if your fingers tremble. Vision loss: Do you see worse than before the transplant?
be seen in the patients evaluated more than 5 years after HT. Limb coldness was also more frequent in this group of patients. In contrast, impotence was significantly less common in such patients. All other adverse effects occurred with a similar frequency in both study periods. DISCUSSION
The immunosuppressive state required for graft viability and the adverse effects attributable to the administration of immunosuppressive therapy are the basis underlying the most frequent complications following heart transplant.7 The need to suppress the immune system through chronic immunosuppressive medication in order to prevent graft rejection is common to all types of transplant. In most centers, triple therapy comprising CyA, azathioprine, and steroids is used. Although the extent of immunosuppression is reduced over time as the risk of rejection decreases, the side effects of immunosuppressive drugs remain important. Although kidney failure, systemic infection, neoplasms, and high blood pressure are the most worrisome adverse effects related to immunosuppressants, the present study centers on those effects that, while not life-threatening, are nevertheless important because of their high incidence and impact upon the patient’s quality of life. These adverse Table 2. Side Effects of Immunosuppressive Therapy (N ⫽ 63)
Vision loss Hypertrichosis Gingival hyperplasia Flushing Impotence Cataracts Tremor Coldness Osteoporosis Mycosis
Incidence
ⱕ5 years (N ⫽ 46)
⬎5 years (N ⫽ 17)
p
49% 43% 38% 38% 35% 30% 24% 16% 13% 5%
52% 37% 28% 39% 41% 28% 20% 9% 13% 4%
41% 59% 65% 35% 18% 35% 35% 35% 12% 6%
0.4 0.1 0.006 0.8 0.04 0.6 0.2 0.03 0.9 0.8
effects were evaluated by means of interviews conducted during routine monitoring visits to the cardiology outpatient clinic. The presence of diminished vision in transplant patients is an event related to multiple factors, such as age, neurological disorders, cataracts, peripheral vascular disease, and so on. Diminished vision is a very common and difficult-toassess complication. In the patient survey, almost 50% of the patients interviewed indicated significant vision loss. Cataracts have been related to the administration of corticoids, and the incidence has varied widely in the different reports. Matsunami et al8 reported a frequency of 34% among kidney transplant patients. However, it should be pointed out that the corticoid doses used in this study were substantially higher. Hypertrichosis is one of the adverse effects most frequently related to CyA treatment. Hypertrichosis in the face, shoulders, arms, and back has been reported in at least 50% of patients given CyA. In our study the overall incidence of hypertrichosis was 43%; both sexes were equally affected, and no differences were found between the study periods. Kahan et al9 noted a marked decrease in the presence of hypertrichosis over time in kidney transplant patients, with a drop in incidence from 53% in the first months following surgery to only 5% at 5 years. Gingival hyperplasia, with an increase in the number of gingival fibroblasts and their collagen production, is clearly related to CyA treatment.10 The condition is more common in the first few months after transplant and in patients with poor oral hygiene. Interestingly, this side effect is greatly enhanced when certain drugs are associated with CyA. Thus, CyA alone has been reported to cause about a 10% incidence of gingival hyperplasia, as compared to up to 50% when administered in combination with nifedipine or diltiazem.11,12 In our series the incidence was 38%, with a higher frequency in those patients evaluated more than 5 years after HT. Of note is the fact that all patients who showed gingival hyperplasia in this period were taking one of the above-cited calcium channel blockers, which could account for the high incidence of gingival hyperplasia seen in this patient subgroup. Along with gingival hyperplasia, facial flushing is a typical and frequent adverse effect of CyA. This adverse effect is persistent, and does not vary in incidence over posttransplant time. It probably results from changes in vascular reactivity caused by this drug. Sexual dysfunction, and specifically impotence, is common in transplant patients. Cyclosporine may cause endocrine and metabolic changes, including modifications in plasma testosterone levels, gynecomastia, and altered spermatogenesis. Drug interactions may also be responsible for these effects. In fact, impotence has been described in relation to drugs frequently used in these patients, such as nifedipine,13 enalapril,14 and gemifibrozil.15 However, it should be pointed out that many of these patients are diabetics suffering from peripheral arterial disease, which contributes to a high incidence of this effect. We have
IMMUNOSUPPRESSANT SIDE EFFECTS
recorded a decrease in the incidence of this effect after 5 years, possibly related to less sexual activity over time. Neurological side effects occur in approximately 20% to 25% of patients,16 and are highly diverse. Of note is the development of mood changes, fine tremors and headache, visual disturbances and cortical blindness, seizures, and coma.17 Essential tremor is the most common effect (24% of patients studied), with no significant differences being found between the study periods. The appearance of tremor is related to an increased serotoninergic activity induced by CyA at the neuronal level.18 Coldness of the hands and feet is a multifactorial phenomenon in which neurogenic and vascular changes play a significant role. In addition, a Raynaud’s phenomenon has been reported that can be attributed to CyA. In our study, the overall incidence of cold hands and feet was 16%, but the salient finding was that it tended to occur more frequently in patients with longer posttransplant evolution times. Peripheral arterial disease is probably a significant explanation for this trend. Osteoporosis is an important source of morbidity following HT, and limits patient rehabilitation and quality of life. Osteoporosis was initially almost exclusively attributed to corticoids, since their effects upon bone—increasing bone resorption and decreasing bone formation—result in a diminished bone mass and an increased risk of fractures.19 However, the influence of CyA in the development of osteoporosis, as shown in animal models, should also be stressed.20 This is consistent with our own results, where 13% of patients suffered disabling bone pain, mainly at lumbar level, with no significant differences being found between patients taking corticoids. No differences were seen either in the two time periods examined. It is important to stress that our immunosuppressive treatment protocol includes Deflazacort, which has fewer negative effects upon bone and its metabolism. Nail mycosis is closely related to corticoid treatment. Its incidence in these patients is usually low (5%). As a result, nail mycosis is not routinely evaluated in studies that analyze the side effects of immunosuppressants in transplant patients. We believe the incidences of side effects recorded in the present study to be very reliable—mainly due to the homogeneity afforded by questionnaire compilation by the same physician. Conversely, we consider the two main limitations
2521
of our study to be its cross-sectional design (involving different patients) and the relatively few number of patients in the second study period. The results obtained in the present study thus show the incidence of side effects after heart transplant to be very high (only 13% of the patients had no side effects). Vision loss and hypertrichosis are of particular note, as they occurred in almost half of all cases. Furthermore, the incidence of these effects varied according to the posttransplant period analyzed, although further research involving a greater number of patients is required to clarify this issue.
REFERENCES 1. Arizo ´n JM: Rev Esp Cardiol 49:781, 1996 2. Pulpo ´n LA, Anguita M: Rev Esp Cardiol 47:687, 1994 3. Arizo ´n JM: Rev Esp Cardiol 48 (suppl 7):71, 1995 4. Copeland JG, Mammana RB, Fuller JK, et al: JAMA 251: 1563, 1984 5. Emery RW, Cork R, Christensen R, et al: Chest 90:29, 1986 6. Oyer PE, Stinson EB, Jamieson SW: Transplant Proc 15 (suppl 1):2546, 1983 7. Crespo MG, Hermida LF, Portela F: Medicine 7(24):1002, 1996 8. Kahan BD, Flechner SM, Lorber MI, et al: Transplantation 43:197, 1987 9. Kahan BD: N Engl J Med 321:1725, 1989 10. Erer B, Polchi P, Lucarelli G, et al: Bone Marrow Transplant 18:157, 1996 11. Shuto H, Kataoka Y, Kanaya A, et al: Eur J Pharmacol 341(1):33, 1988 12. Wysocki GP, Gretzinger HA, Laupacis A, et al: Oral Surg Oral Med Oral Pathol 55:274, 1983 13. Thomason JM, Seymour RA, Ellis JS, et al: J Periodontol 66:742, 1995 14. King GN, Fulinfaw R, Higgins TJ, et al: J Clin Periodontol 20:286, 1993 15. Lukert BP, Raisz LG: Ann Intern Med 112:352, 1990 16. Schlosberg M, Movsowitz C, Epstein S: Endocrinology 124: 2179, 1989 17. Matsunami C, Hilton AF, Dyer JA, et al: Aust N Z J Ophthamol 22(1):53, 1994 18. Martinez-Garcia F: Aten Primaris (Letter). 9:178, 1992 19. Pertusa S, Bueno JM, Quirce F: Med Clin (Barc) (Letter). 98(2):78, 1992 20. Alcala´ JN, Prada JL: (Letter). An Med Interna 15(3):175, 1998
H
EART transplant (HT) is currently the treatment of choice in patients with severe heart disease in a poor clinical condition and not amenable to improvement with alternative therapies.1 These patients require chronic and sustained administration of immunosuppressive drugs to decrease the incidence and severity of graft rejection.2 In most centers, the immunosuppressive protocol used is the triple therapy with cyclosporine, azathioprine, and steroids. Because immune activity and the trend toward rejection are most marked in the first few months’ posttransplant, most regimens provide higher doses during this initial period, followed by gradual dose decrements until maintenance levels are reached. However, and despite the use of increasingly lower doses, the morbidity associated to immunosuppressive medication remains high.3– 6 The purpose of this study was to ascertain the frequency of side effects caused by the immunosuppressive drugs commonly used after HT, and the differences in their midand long-term incidence. MATERIALS AND METHODS Patients and Study Design Sixty-three consecutive HT patients subjected to routine follow-up in the cardiology outpatient clinic of our hospital were analyzed. There were 55 males and 8 females, with a mean age of 49 ⫾ 12 years (range 14 to 67 years). All patients were in a stable condition, with a time elapsed from transplant of more than 18 months. The disease leading to HT was idiopathic dilated cardiomyopathy (26 cases), ischemic heart disease (25 cases), valvular diseases (7 cases), and other conditions (7 cases). At the end of their routine follow-up visit, patients were administered a questionnaire to determine the side effects of immunosuppressive therapy. The questionnaire was always applied by the same physician. The answers were then analyzed to assess the overall incidence of each variable and the difference between the incidence rate of the effect before and after 5 years’ posttransplant.
Immunosuppressive Protocol The immunosuppressive protocol was the one routinely used in our center, and it consisted of cyclosporine (CyA) and azathioprine before surgery, followed by induction with OKT3 and maintenance with CyA, azathioprine, and steroids after transplant. The same protocol was given to all patients. Cyclosporine was given at doses appropriate to achieve levels ranging from 200 to 300 ng/mL in the first 6 months, and 100 to 200 ng/mL thereafter. The standard azathioprine dose was 2 mg/kg per
day, maintaining a WBC count above 4000/mm3. The steroid used was Deflazacort in all cases, at an initial dose of 1.2 mg/kg per day, followed by gradual decrements; 1 month after HT, the mean dose administered was 21 mg/d, as compared to 15 mg/d after one year. In our protocol, an attempt to discontinue Deflazacort is made. Drug discontinuation was achieved in 24 of the 63 patients included in the present study (38%).
Variables Analyzed A survey was made of the side effects of immunosuppression. The variables analyzed were vision loss, cataracts, cold hands and feet, gingival hypertrophy, impotence, nail mycosis, increased skin pigmentation or redness, disabling osteoporosis, hypertrichosis, and trembling of the hands (Table 1).
Statistical Analysis The variables analyzed were recorded as percentages. Comparisons were made using the chi-squared (with Yates’ continuity correction) and Fisher F tests (for small groups). A value of P ⱕ .05 was considered statistically significant.
RESULTS Overall Side Effects
The incidence of side effects attributable to immunosuppressive treatment is shown in Table 2. Diminished vision, recorded in almost 50% of cases, was the most common secondary effect. Of note is the high incidence of cataracts (up to 30%). Tremor was the most frequent neurological adverse effect (24%). In turn, skin reddening and hyperpigmentation occurred in 38% of cases, while gingival hyperplasia and hypertrichosis (both typical of CyA treatment) were recorded in 38% and 43% of patients, respectively. The incidence of cold hands and feet, disabling bone pain, and nail mycosis was less significant. Most patients studied had at least one side effect. Only 13% were free of effects. Side Effects According to Time Periods
Table 2 summarizes the incidence of side effects by time periods. An increased incidence of gingival hyperplasia can From the Department of Cardiology, La Fe University Hospital, Valencia, Spain. Address reprint requests to Luis Almenar, Clinical Cardiology Section, Dept of Cardiology, La Fe University Hospital, 46-020 Valencia, Spain.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0041-1345/99/$–see front matter PII S0041-1345(99)00444-3
Transplantation Proceedings, 31, 2519–2521 (1999)
2519
2520
ALEMENAR, RUEDA, OSA ET AL Table 1. Questionnaire
Cataracts: Has the ophthalmologist told you that you have cataracts? Cold hands and feet: Do your hands and feet easily become cold— unlike before transplant? Gingival hypertrophy: Do you notice inflammation of the gums? Impotence: Do you feel a lessened sex urge or erection problems? Compared to pretransplant situation? Nail mycosis: Do your nails break easily at the edges? Did the dermatologists say it’s a fungal infection? Increased skin pigmentation: Do you easily become red or tanned spontaneously or following minor exposure to sunlight? Disabling osteoporosis: Do you suffer bone pain that limits daily activities? Hypertrichosis: Do you notice an increase in hairiness? Trembling of the hands: Have you tremor in the fingers? Spread your hands to see if your fingers tremble. Vision loss: Do you see worse than before the transplant?
be seen in the patients evaluated more than 5 years after HT. Limb coldness was also more frequent in this group of patients. In contrast, impotence was significantly less common in such patients. All other adverse effects occurred with a similar frequency in both study periods. DISCUSSION
The immunosuppressive state required for graft viability and the adverse effects attributable to the administration of immunosuppressive therapy are the basis underlying the most frequent complications following heart transplant.7 The need to suppress the immune system through chronic immunosuppressive medication in order to prevent graft rejection is common to all types of transplant. In most centers, triple therapy comprising CyA, azathioprine, and steroids is used. Although the extent of immunosuppression is reduced over time as the risk of rejection decreases, the side effects of immunosuppressive drugs remain important. Although kidney failure, systemic infection, neoplasms, and high blood pressure are the most worrisome adverse effects related to immunosuppressants, the present study centers on those effects that, while not life-threatening, are nevertheless important because of their high incidence and impact upon the patient’s quality of life. These adverse Table 2. Side Effects of Immunosuppressive Therapy (N ⫽ 63)
Vision loss Hypertrichosis Gingival hyperplasia Flushing Impotence Cataracts Tremor Coldness Osteoporosis Mycosis
Incidence
ⱕ5 years (N ⫽ 46)
⬎5 years (N ⫽ 17)
p
49% 43% 38% 38% 35% 30% 24% 16% 13% 5%
52% 37% 28% 39% 41% 28% 20% 9% 13% 4%
41% 59% 65% 35% 18% 35% 35% 35% 12% 6%
0.4 0.1 0.006 0.8 0.04 0.6 0.2 0.03 0.9 0.8
effects were evaluated by means of interviews conducted during routine monitoring visits to the cardiology outpatient clinic. The presence of diminished vision in transplant patients is an event related to multiple factors, such as age, neurological disorders, cataracts, peripheral vascular disease, and so on. Diminished vision is a very common and difficult-toassess complication. In the patient survey, almost 50% of the patients interviewed indicated significant vision loss. Cataracts have been related to the administration of corticoids, and the incidence has varied widely in the different reports. Matsunami et al8 reported a frequency of 34% among kidney transplant patients. However, it should be pointed out that the corticoid doses used in this study were substantially higher. Hypertrichosis is one of the adverse effects most frequently related to CyA treatment. Hypertrichosis in the face, shoulders, arms, and back has been reported in at least 50% of patients given CyA. In our study the overall incidence of hypertrichosis was 43%; both sexes were equally affected, and no differences were found between the study periods. Kahan et al9 noted a marked decrease in the presence of hypertrichosis over time in kidney transplant patients, with a drop in incidence from 53% in the first months following surgery to only 5% at 5 years. Gingival hyperplasia, with an increase in the number of gingival fibroblasts and their collagen production, is clearly related to CyA treatment.10 The condition is more common in the first few months after transplant and in patients with poor oral hygiene. Interestingly, this side effect is greatly enhanced when certain drugs are associated with CyA. Thus, CyA alone has been reported to cause about a 10% incidence of gingival hyperplasia, as compared to up to 50% when administered in combination with nifedipine or diltiazem.11,12 In our series the incidence was 38%, with a higher frequency in those patients evaluated more than 5 years after HT. Of note is the fact that all patients who showed gingival hyperplasia in this period were taking one of the above-cited calcium channel blockers, which could account for the high incidence of gingival hyperplasia seen in this patient subgroup. Along with gingival hyperplasia, facial flushing is a typical and frequent adverse effect of CyA. This adverse effect is persistent, and does not vary in incidence over posttransplant time. It probably results from changes in vascular reactivity caused by this drug. Sexual dysfunction, and specifically impotence, is common in transplant patients. Cyclosporine may cause endocrine and metabolic changes, including modifications in plasma testosterone levels, gynecomastia, and altered spermatogenesis. Drug interactions may also be responsible for these effects. In fact, impotence has been described in relation to drugs frequently used in these patients, such as nifedipine,13 enalapril,14 and gemifibrozil.15 However, it should be pointed out that many of these patients are diabetics suffering from peripheral arterial disease, which contributes to a high incidence of this effect. We have
IMMUNOSUPPRESSANT SIDE EFFECTS
recorded a decrease in the incidence of this effect after 5 years, possibly related to less sexual activity over time. Neurological side effects occur in approximately 20% to 25% of patients,16 and are highly diverse. Of note is the development of mood changes, fine tremors and headache, visual disturbances and cortical blindness, seizures, and coma.17 Essential tremor is the most common effect (24% of patients studied), with no significant differences being found between the study periods. The appearance of tremor is related to an increased serotoninergic activity induced by CyA at the neuronal level.18 Coldness of the hands and feet is a multifactorial phenomenon in which neurogenic and vascular changes play a significant role. In addition, a Raynaud’s phenomenon has been reported that can be attributed to CyA. In our study, the overall incidence of cold hands and feet was 16%, but the salient finding was that it tended to occur more frequently in patients with longer posttransplant evolution times. Peripheral arterial disease is probably a significant explanation for this trend. Osteoporosis is an important source of morbidity following HT, and limits patient rehabilitation and quality of life. Osteoporosis was initially almost exclusively attributed to corticoids, since their effects upon bone—increasing bone resorption and decreasing bone formation—result in a diminished bone mass and an increased risk of fractures.19 However, the influence of CyA in the development of osteoporosis, as shown in animal models, should also be stressed.20 This is consistent with our own results, where 13% of patients suffered disabling bone pain, mainly at lumbar level, with no significant differences being found between patients taking corticoids. No differences were seen either in the two time periods examined. It is important to stress that our immunosuppressive treatment protocol includes Deflazacort, which has fewer negative effects upon bone and its metabolism. Nail mycosis is closely related to corticoid treatment. Its incidence in these patients is usually low (5%). As a result, nail mycosis is not routinely evaluated in studies that analyze the side effects of immunosuppressants in transplant patients. We believe the incidences of side effects recorded in the present study to be very reliable—mainly due to the homogeneity afforded by questionnaire compilation by the same physician. Conversely, we consider the two main limitations
2521
of our study to be its cross-sectional design (involving different patients) and the relatively few number of patients in the second study period. The results obtained in the present study thus show the incidence of side effects after heart transplant to be very high (only 13% of the patients had no side effects). Vision loss and hypertrichosis are of particular note, as they occurred in almost half of all cases. Furthermore, the incidence of these effects varied according to the posttransplant period analyzed, although further research involving a greater number of patients is required to clarify this issue.
REFERENCES 1. Arizo ´n JM: Rev Esp Cardiol 49:781, 1996 2. Pulpo ´n LA, Anguita M: Rev Esp Cardiol 47:687, 1994 3. Arizo ´n JM: Rev Esp Cardiol 48 (suppl 7):71, 1995 4. Copeland JG, Mammana RB, Fuller JK, et al: JAMA 251: 1563, 1984 5. Emery RW, Cork R, Christensen R, et al: Chest 90:29, 1986 6. Oyer PE, Stinson EB, Jamieson SW: Transplant Proc 15 (suppl 1):2546, 1983 7. Crespo MG, Hermida LF, Portela F: Medicine 7(24):1002, 1996 8. Kahan BD, Flechner SM, Lorber MI, et al: Transplantation 43:197, 1987 9. Kahan BD: N Engl J Med 321:1725, 1989 10. Erer B, Polchi P, Lucarelli G, et al: Bone Marrow Transplant 18:157, 1996 11. Shuto H, Kataoka Y, Kanaya A, et al: Eur J Pharmacol 341(1):33, 1988 12. Wysocki GP, Gretzinger HA, Laupacis A, et al: Oral Surg Oral Med Oral Pathol 55:274, 1983 13. Thomason JM, Seymour RA, Ellis JS, et al: J Periodontol 66:742, 1995 14. King GN, Fulinfaw R, Higgins TJ, et al: J Clin Periodontol 20:286, 1993 15. Lukert BP, Raisz LG: Ann Intern Med 112:352, 1990 16. Schlosberg M, Movsowitz C, Epstein S: Endocrinology 124: 2179, 1989 17. Matsunami C, Hilton AF, Dyer JA, et al: Aust N Z J Ophthamol 22(1):53, 1994 18. Martinez-Garcia F: Aten Primaris (Letter). 9:178, 1992 19. Pertusa S, Bueno JM, Quirce F: Med Clin (Barc) (Letter). 98(2):78, 1992 20. Alcala´ JN, Prada JL: (Letter). An Med Interna 15(3):175, 1998