Representativeness of EXPLORER-HCM trial and prevalence of eligibility criteria for Mavacamten in a nationwide cohort

Introduction

The EXPLORER-HCM trial evaluated the safety and efficacy of Mavacamten, a cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy (HCM). Mavacamten improved symptoms, exercise capacity and left ventricular outflow tract (LVOT) obstruction. However, the proportion of patients eligible for this therapy in real practice remains unclear.

Purpose

To determine the prevalence of eligibility criteria for Mavacamten and to describe the profile of patients complying with EXPLORER-HCM criteria in a nationwide cohort.

Methods

Cross-sectional study including all HCM patients enrolled in a European country-based nationwide registry. Presence of EXPLORER-HCM inclusion [≥18 years, obstructive HCM (LVOT gradient ≥50 mmHg), left ventricular ejection fraction (LVEF) ≥55%, New York Heart Association (NYHA) class II–III] and exclusion criteria [syncope or sustained ventricular tachycardia with exercise] were analyzed.

Results

Of 1042 patients included in this analysis (57.8% male, mean age at diagnosis 52 years, 39.6% obstructive HCM), 45 met the EXPLORER-HCM inclusion criteria and, after applying exclusion criteria, 30 patients were eligible for therapy with Mavacamten.

Eligible patients were all Caucasian, mostly female (63.3%), with a mean age at diagnosis of 58±14 years. All patients presented with heart failure symptoms, and were mostly in NYHA class II (83.3%); 4 patients (13.3%) presented with atrial fibrillation. In the baseline echocardiogram, mean LVEF was 68±9%; mean interventricular septum thickness was 20±4 mm; most patients presented with systolic anterior motion of the mitral valve (96.7%) and mitral regurgitation (96.7%). In cardiac magnetic resonance imaging evaluation, maximal wall thickness was 22±4 mm and 76.9% had late gadolinium enhancement. A pathogenic or likely pathogenic HCM gene variant was identified in 5 patients (MYH7 and MYBPC3 gene mutations).

In this group, 86.2% of patients were treated with beta-blockers and 34.5% with calcium channel antagonists. Only 1 patient was on Disopyramide. Septal reduction techniques were used in 43.3% of patients: alcohol septal ablation and septal myectomy were performed in 7 (23.3%) and 6 (20.0%) patients, respectively. Cardioverter-defibrillators were implanted in 2 patients for primary prevention of sudden cardiac death, and 6 patients received a pacemaker for bradycardia indications.

Conclusion

Specific therapies remain an unmet need in HCM. In this large nationwide cohort, only 2.9% of patients were eligible for therapy with Mavacamten according to EXPLORER-HCM criteria. Among patients complying with the study criteria, invasive septal reduction therapies were offered to a high proportion of patients. Further real-world data are warranted to estimate the proportion of HCM patients that will benefit from Mavacamten.

Funding Acknowledgement

Type of funding sources: None.

Predictors of left ventricular dysfunction in hypertrophic cardiomyopathy: results from a nationwide registry

Introduction

Progression of hypertrophic cardiomyopathy (HCM) with incident left ventricular (LV) dysfunction (HCM-LVSD) is associated with poor prognosis and advanced heart failure (HF). Prevalence ranges from 5–10% in previous studies. Identification of predictors of adverse remodeling may improve risk stratification and prognostication in HCM.

Purpose

To identify predictors of HCM-LVSD in a nationwide cohort of HCM patients (pts).

Methods

Retrospective study including all HCM pts enrolled in a European country-based nationwide registry. HCM-LVSD group included pts with LV ejection fraction (LVEF) ≤50% at baseline and pts who developed LV dysfunction/dilated phenotype during follow-up. Multivariate logistic regression was performed to identify predictors of HCM-LVSD.

Results

1042 HCM patients (57.8% male, mean age at diagnosis 52 years) were included, of whom 81 (8%) belonged to the HCM-LVSD group. HCM-LVSD pts were mostly male (60.5%) and tended to be older at the time of diagnosis than those without LVSD (55 vs 52 years, p=0.054). HCM-LVSD pts were more often symptomatic at the index visit (84.1% vs 65.2%, p<0.001), with more functional impairment (New York Heart Association class III–IV: 18.5% vs 9.2%, p=0.021). Atrial fibrillation (21.3% vs 8.6%, p<0.001) and intraventricular conduction disturbances (28.6% vs 14.4%, p=0.002) were more prevalent in HCM-LVSD pts. HCM-LVSD pts had higher baseline left atrium (LA) volumes (52 vs 39 ml, p=0.001), lower LVEF (50 vs 67%, p<0.001) and higher rates of mitral regurgitation (79.0% vs 65.1%, p=0.011). Prevalence of obstructive HCM was lower in the HCM-LSVD group (25.3% vs 40.9%, p=0.007). Presence of late gadolinium enhancement (92.6% vs 74.6%, p=0.035) was more common in pts with LVSD. Baseline N-terminal pro–B-type natriuretic peptide was higher in HCM-LVSD (3839 vs 1281 pg/ml, p=0.027). There were no differences in the number and type of genetic variants between groups. In HCM-LVSD pts, implantation of cardioverter-defibrillators for secondary prevention was more frequent (28.6% vs 6.4%, p=0.002), as was the use of pacemaker (16.7% vs 7.0%, p=0.002). During a mean follow-up of 5.3±6.1 years, hospitalization for HF (50.0% vs 11.3%) and all-cause mortality (12.3% vs 2.9%, p<0.001) were more frequent in HCM-LVSD group.

After multivariate analysis, higher LA volume (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01–1.05, p=0.003) and nonobstructive HCM (OR 2.74, 95% CI 1.03–7.27, p=0.043) were independent predictors of HCM-LVSD.

Conclusions

In this large nationwide cohort of HCM pts, prevalence of LVSD was 8%, in line with existing literature. In this cohort, larger LA volumes and nonobstructive HCM predicted progression to HCM-LVSD.

Funding Acknowledgement

Type of funding sources: None.

The impact of mitral regurgitation grade on exercise capacity following cardiac rehabilitation program after transcatheter aortic valve implantation

Introduction

Severe aortic stenosis (AS) and mitral regurgitation (MR) often coexist. Transcatheter aortic valve implantation (TAVI) is becoming widely used for the treatment of patients (pts) with symptomatic severe AS. However, conflicting data reside concerning the impact of MR on outcomes after TAVI. Also, very few data exist regarding the benefits of a cardiac rehabilitation program (CRP) following TAVI in pts with MR.

Purpose

To evaluate the effect of a CRP in functional parameters after TAVI, particularly in pts with MR grade ≥ II.

Methods

Retrospective study which included all pts submitted to TAVI between 2014 and 2020 that completed a CRP following the procedure. Cardiopulmonary exercise tests (CPET) were performed after TAVI at baseline (pre-CRP) and post-CRP. We evaluated pre- and post-CRP peak oxygen consumption (pVO2), pVO2 at the anaerobic threshold (AT), respiratory exchange ratio (RER), VE/VCO2 and CPET duration. The exercise protocol included low/medium intensity exercises and consisted of sessions 3 times per week carried over 3 months. MR grading severity was assessed with transthoracic echocardiography performed after TAVI and was divided into 2 groups (grade < II vs grade ≥ II).

Results

Fifty-two pts were included, 59,6% were male, mean age of 78,6±8,6 years-old. Mean Society of Thoracic Surgery (STS) risk score was 4,9. Mean pre-TAVI aortic valve area was 0,68 cm2, with a mean gradient of 45,5 mmHg and a mean ejection fraction (EF) of 51%. The majority of pts implanted a self-expandable prosthesis (55,8%).

Twenty-seven (51,9%) pts had MR grade ≥ II. Baseline characteristics were similar between pts with MR grade < II vs MR grade ≥ II, with the exception of the prevalence of coronary artery disease which was higher in MR grade ≥ II (p=0,036). Patients with MR grade < II had higher maximum and median aortic gradients before TAVI (p<0,05 for all). The mean number of cardiac rehabilitation sessions was 21±7, without differences between both groups. In pts with MR grade ≥ II, there was an improvement in CPET duration after CRP (HF protocol from 03:57 min to 05:02 min; p=0,017 and modified Bruce protocol from 06:03 min to 06:41 min; p=0,049) but without significant changes in pVO2 (14,7 mL/kg/min to 14,9 mL/kg/min; p=0,990), RER or VEVCO2/VO2 ratio. Patients with MR grade < II significantly improved pVO2 (13,8 mL/kg/min to 14,7 mL/kg/min; p=0,015), and CPET duration with HF protocol from 05:04 min to 06:23 min; p=0,006 after CRP. There was also an improvement in VEVCO2/VO2 ratio, although not statically significant.

Conclusions

Patients with MR grade < II after TAVI who underwent a CRP significantly improved pVO2 and CPET duration. Although pts with MR grade ≥ II did not improved pVO2 after a CRP, an improvement in CPET duration may translate into a clinical benefit in these pts. These results highlight the importance of further research and personalization among this potentially higher risk subset of pts.

Funding Acknowledgement

Type of funding sources: None.

Teaching and learning in a multilingual Europe: findings from a cross-European study

School classrooms within the EU are multilingual learning environments. The diversity of pupils in classrooms raises significant challenges for teachers, but to date, there are no data from large-scale surveys that compare views within and across European countries. A bespoke questionnaire was designed to examine views of current classroom learning environments with respect to the multilingualism. The questionnaire was piloted and subsequently completed by 2792 teachers across different European countries. Eleven countries provided sufficient data for analyses. Results from structural equation modelling showed that teachers’ attitudes could be reliably measured across Europe with the use of carefully devised questionnaire, whose loading and factor structure remained invariant across countries. Teachers’ views about multilingualism were most challenged by the numbers of children in their classes, not the percentage of multilingual pupils in the class. Countries differed in how they perceived multilingualism, with their differences leading to distinctive country clusters. Gender and education level (elementary vs. secondary) differences were also observed irrespective of country. These findings enhance our understanding of the role that the characteristics of teachers and their classrooms play in a multilingual setting across diverse European settings. The practical relevance of the results and new opportunities for teacher training are discussed.

Early discharge after TAVI: should we still be afraid of conduction disturbances?

Introduction

Conduction disturbances (CD) after TAVI remains the most frequent complication of the procedure, frequently increasing the length of hospital stay. A lack of consensus exists regarding in-hospital management of CD post-TAVI.

Purpose

To evaluate if an early discharge (ED) protocol could be safely implemented in patients (pts) with CD post-TAVI.

Methods

Retrospective study of all pts submitted to TAVI between 2016 and 2018. Pts with prior permanent pacemaker (PP) and non-transfemoral approach were excluded. ECG data before, immediately after the procedure and at day 3 post-TAVI were collected, and continuous telemetry monitoring was recorded. We applied a recently proposed ED algorithm (adapted from Management of Conduction Disturbances Associated With Transcatheter Aortic Valve Replacement - JACC Scientific Expert Panel; JACC 2019; 74(8):1086–106) to identify which pts could have been candidates for ED. ED was defined as discharge in the first 72 hours (h) after the procedure. We evaluated if an ED strategy would have been safe at 1-year follow-up (FUP), as defined by the absence of need for PP, syncope and mortality.

Results

242 pts were included, 44,8% males, mean age 80,4 years, mean Euroscore II 5,4 and the majority implanted a self-expandable prosthesis (64,1%). Mean hospital stay after TAVI was 7,7 days. The most frequent CD after TAVI were: new onset left bundle brunch block (36%) and high degree atrioventricular block (HAVB) (16,3%). During hospital stay 21,6% needed PP, mainly because of HAVB (mainly implanted in the first 72h).

According to the proposed algorithm, 70,7% of our pts were ED-candidates. ED-candidates had lower prevalence of predilation (18,5% vs 36,8%, p=0,008) with no significant differences between type of prosthesis or baseline ECG. ED-candidates had smaller PR interval post-TAVI (184,5 vs 202,5 ms, p=0,044) and smaller PR and QRS at 72h (p<0,001 in both).

At 1-year FUP, only 2,3% of ED-candidates needed a PP (vs 37,7% non-ED, p<0,001). It is noteworthy that in those ED-candidates who needed a PP during FUP, the percentage of ventricular pacing was less than 2% at 6 months. In the FUP period, 3,2% of ED candidates presented at the ER because of syncope, with no significant differences to non-ED pts. No differences between groups were found in 30-days and 1-year ER presentation because of syncope or all-cause mortality.

Conclusions

According to the proposed algorithm for ED in pts with CD post-TAVI, pts with specific ECG characteristics and without rhythm events during continuous telemetry monitoring can be early discharged with long-term safety.

Funding Acknowledgement

Type of funding source: None

P5270Impaired myocardial deformation assessed by cardiac magnetic resonance is associated with increased arrhythmic risk in hypertrophic cardiomyopathy

Background

Strain techniques, such as feature tracking cardiac magnetic resonance (FT-CMR), have emerged as a promise for more accurate evaluation of cardiac function compared to ejection fraction. In hypertrophic cardiomyopathy (HCM) patients, impaired myocardial deformation measured by FT-CMR has been associated with severity of hypertrophy and presence of late gadolinium enhancement (LGE) but associations with clinical severity and prognosis are scarce.

Purpose

To analyse the association between left ventricular strain measured by FT-CMR, morphologic features and prognostic markers in patients with HCM.

Methods

Retrospective analysis of clinical, echocardiography, Holter and CMR data of HCM patients aged ≥16 years followed at two referral centres. Ventricular arrhythmias (VA) were defined as non-sustained or sustained ventricular tachycardia or sudden cardiac arrest. Sudden cardiac death (SCD) risk was evaluated using the score proposed by the European Society of Cardiology. LGE extension was evaluated using the American Heart Association 17-segment model. FT-CMR was used to evaluate global peak systolic longitudinal (GLS), radial (GRS) and circumferential (GCS) strains - GLS was averaged from three standard longitudinal views while GRS and GCS were averaged from the basal, mid and apical LV short-axis planes.

Results

A total of 109 HCM patients (59.2±16.2 years old; 60.6% males) were included; mean follow-up was 39±25 months. Mean LV mass was 170.6±70.3g, LVEF was 63.7±10.0% and the number of segments with LGE was 3.14±3.32. Mean GLS, GRS and GCS were −14.8±4.0%, 34.4±13.3% and −17.5±4.8%, respectively. Impaired strain was associated with higher LV mass (GLS: r=0.46, GRS: r=−0.46, GCS: r=0.47, p<0.001 for all), reduced LVEF (GLS: r=−0,33, GRS: r=0,44, GCS: r=−0.41, p<0.003 for all) and LGE extension (GLS: r=0.26, GRS: r=−0.38, GCS: r=0.38, p<0.01 for all).

SCD risk score was 3.12%±2.98 (8 patients scored as high risk) and VA were documented in 26 patients (26%). Patients with VA had worse strain values than those without (GLS −13.2±4.12 vs −15.5±3.71, p=0.011; GCS −15,8±5.22 vs −18.3±4.24, p=0.017). Patients with high estimated risk of SCD also had worse strain values than those at low/intermediate risk (GLS −12.2±3.57 vs −15.1±3.83, p=0.048; GCS −14.5±4.26 vs −17.9±4.54, p=0.047). A correlation between SCD risk and GLS and GCS was observed (r=0.32, p=0.004; r=0.23, p=0.03, respectively).

Conclusions

In our population, worse strain measurements were associated with a more severe HCM phenotype, presence of VA and a higher estimated risk of SCD. Strain assessed by FT-CMR may improve risk stratification in HCM patients.

The MSH2 c.388_389del mutation shows a founder effect in Portuguese Lynch syndrome families

The MSH2 c.388_389del mutation has occasionally been described in Lynch families worldwide. At the Portuguese Oncology Institute in Porto, Portugal, we have identified 16 seemingly unrelated families with this germline mutation. To evaluate if this alteration is a founder or a recurrent mutation we performed haplotype analysis in the 16 Portuguese index cases and 55 relatives, as well as in four index cases and 13 relatives reported from Germany, Scotland, England, and Argentina. In the Portuguese families we observed a shared haplotype of approximately 10 Mb and all were originated from the north of Portugal. These results suggest that this alteration is a founder mutation in Portugal with a relatively recent origin. In the reported families outside Portugal with this mutation different haplotype backgrounds were observed, supporting the hypothesis that it occurred de novo on multiple occasions. We also conclude that the high proportion of families with the MSH2 c.388_389del mutation indicates that screening for this alteration as a first step may be cost-effective in the genetic testing of Lynch syndrome suspects of Portuguese ancestry, especially those originating from the north of Portugal.

MSH6 germline mutations in early-onset colorectal cancer patients without family history of the disease

Germline MLH1 and MSH2 mutations are scarce in young colorectal cancer patients with negative family history of the disease. To evaluate the contribution of germline MSH6 mutations to early-onset colorectal cancer, we have analysed peripheral blood of 38 patients diagnosed with this disease before 45 years of age and who presented no family history of hereditary nonpolyposis colorectal cancer-related cancers. Blood samples from 108 healthy volunteers were analysed for those genetic alterations suspected to affect the function of MSH6. Of the seven (18.4%) MSH6 alterations found, we have identified three novel germline mutations, one 8 bp deletion leading to a truncated protein and two missense mutations resulting in the substitution of amino acids belonging to different polarity groups. High-frequency microsatellite instability was found in the patient with the MSH6 deletion, but not in the other 27 carcinomas analysed. No MLH1 promoter methylation was detected in tumour tissue. Our findings suggest that germline MSH6 mutations contribute to a subset of early-onset colorectal cancer. Further studies are warranted to understand the genetic and environmental factors responsible for the variable penetration of MSH6 germline mutations, as well as to identify other causes of early-onset colorectal cancer.

Evaluation of recombinant antigens for serodiagnosis of Chagas' disease in South and Central America

The commercially available diagnostic tests for Chagas' disease employ whole extracts or semipurified fractions of Trypanosoma cruzi epimastigotes. Considerable variation in the reproducibility and reliability of these tests has been reported by different research laboratories, mainly due to cross-reactivity with other pathogens and standardization of the reagents. The use of recombinant antigens for the serodiagnosis of Chagas' disease is recommended to increase the sensitivity and specificity of serological tests. Expressed in Escherichia coli, as fusion products with glutathione S-transferase, six T. cruzi recombinant antigens (H49, JL7, A13, B13, JL8, and 1F8) were evaluated in an enzyme-linked immunosorbent assay for Chagas' disease. The study was carried out with a panel of 541 serum samples of chagasic and nonchagasic patients from nine countries of Latin America (Argentina, Bolivia, Brazil, Chile, Colombia, El Salvador, Guatemala, Honduras, and Venezuela). The optimal concentration of each recombinant antigen for coating of plates was determined with the help of 125I-labelled recombinant proteins. While the specificity of the epimastigote antigen was 84% because of false positives from leishmaniasis cases, for the recombinant antigens it varied from 96.2 to 99.6%. Recombinant antigens reacted with 79 to 100% of serum samples from chronic chagasic patients. In this way, it is proposed that a mixture of a few T. cruzi recombinant antigens should be employed in a diagnostic kit to minimize individual variation and promote high sensitivity in the diagnosis of Chagas' disease.

[The role of external radiotherapy in the treatment of medullary carcinoma of the thyroid]

Medullary carcinoma of the thyroid represents 3 to 10% of all thyroid cancers. Surgery is the main treatment. External beam radiotherapy has a fundamental role in the treatment of residual disease following surgery, in cases of cervical node involvement, and in unresectable tumors. Between 1975 and 1993, 12 patients with medullary carcinoma of the thyroid were treated at the Department of Radiotherapy of the Portuguese Institute of Oncology in Oporto. Nine of these patients (75%) were male and 3 (25%) female, ranging from 24 to 80 years of age (mean = 43). All of them had residual tumor after surgery and underwent treatment with external beam radiotherapy. The follow-up period ranged from 36 to 180 months, with a median of 78 months; 8 patients (66.7%) are alive, 5 of them show no evidence of disease. Average survival was 70 months, and 4 patients (33%) died with metastatic disease. The aim of this paper is to analyse the role of external beam radiotherapy in local control of these tumors, with a brief review of the literature.

[Gliosarcomas]

Gliosarcomas are rare tumors of the central nervous system with a poor prognosis. Histologically these tumors are characterized by an admixture of neoplastic glial cells and sarcomatous elements. Due to the scarcity of data in literature, the diagnosis is often missed and treatment is difficult. The authors report three cases of cerebral gliosarcomas and review the literature on this subject.

[Monoclonal antibodies. General approach and radioimmunotherapy]

Two major obstacles to systemic cancer therapy are the lack of specificity of therapeutic modalities and the intrapatient and interpatient heterogeneity of cancer cells. Because of their natural specificity, antibodies directed against tumor specific or tumor associated antigens have been raising interest in oncology. This article makes an overview of the basic principles of monoclonal antibodies, their limitations and perspectives, with particular attention to Immunoradioconjugates. The most important Immunoradiotherapy clinical studies are also reviewed.

[Otorhinolaryngologic symptoms caused by the intranasal abuse of cocaine. Report of a case]

Cocaine abuse is associated with medical complications that depends on the route of administration. Intranasal "snorting" is associated with complications secondary to chronic irritation on the nasal mucosa. A case of long-standing intranasal cocaine abuse is presented with unusual complications: septal and palatal necrosis, osteolytic sinusitis and bilateral optic neuropathy. The CT scan demonstrated a soft-tissue mass in etmoid and sphenoidal sinus and orbits. The histopathologic examination revealed a nonspecific pattern of chronic inflammation with no evidence suggestive of infection, neoplasm or lethal midline granuloma. The case had a fatal outcome. Because of the constellation of singular manifestations we discuss the differential diagnosis. Interdisciplinary approach is stressed. Emphasis is made in early diagnosis.

[The clinical experience in Panama with metronidazole in treating Chagas' disease in the acute and chronic phases]

The authors evaluated the serological response of metronidazole, or 8823 RP-(Hydroxy-2' ethy1)-1-methyl-2 nitro-5 imidazole) in 1307 patients, with Chagas' disease in the acute or chronic stage with age ranging between 6 months to 73 years. 273 patients were in the acute phase: 153 children and 120 adults. Patients in the chronic stage were classified with serological, clinical and cardiological criteria: 1.-POSITIVE SEROLOGY without cardiological signs or symptomatology (EKG, VECTO, ECHO M mode and 2-D, Chest Rx, physiological and pharmacological tests, radiocardiological-HMIBI, MUGA); 2.- POSITIVE SEROLOGY with cardiological signs and symptoms (all cardiological tests were abnormals); 3.- POSITIVE SEROLOGY with cardiomyopathy and cardiac failure. Metronidazole, P.O. or I.V. was utilizing dosages ranging from 15 to 25 mg/Kilo body weight per five days in acute phase and 250 to 500 mg. P.O. in the chronic stage of the disease for 180 days. The drug was well tolerated by all patients in both phases of the disease. Adequate anabolic effect was identified in both stages of the illness. Serological reactions were negative in all patients (100%) without cardiomyopathy. In patients with cardiomyopathy and cardiac failure, the complement fixation test title were similar before and after treatment.

Evidence that estramustine binds MAP-1A to inhibit type IV collagenase secretion

Estramustine is a novel anti-microtubule drug shown to bind MAP-1 and MAP-2 (microtubule-associated proteins) in vitro. In this paper we have shown that estramustine specifically binds MAP-1A in Du 145a cells, resulting in disruption of MAP-1A microtubules and inhibition of type IV collagenase secretion. Immunofluorescence studies revealed that at 30 microM levels estramustine blocked type IV collagenase secretion by partial disruption of the MAP-1A microtubule networks. Immunoprecipitation studies with polyclonal antibodies provided quantitative evidence that 30–60 microM estramustine blocked secretion of a 105 × 10(3) Mr type IV collagenase. Pulse-labeling experiments confirmed that the effect was not a result of inhibition of either protein synthesis or altered rates of type IV collagenase turnover. Finally, drug uptake studies with [3H]estramustine, scintillation counting and fluorography demonstrated that the principal target of the drug was MAP-1A. For the first time we have shown that the drug blocks secretion by binding MAP-1A and causing incomplete disruption of the microtubule networks.

Microbiological study of localized juvenile periodontitis in Panama

The occurrence of subgingival Actinobacillus actinomycetemcomitans and Capnocytophaga in 12 localized juvenile periodontitis and 10 gingivitis patients from Panama was determined using selective culture techniques. A actinomycetemcomitans was present in all localized juvenile periodontitis lesions studied and was, on average, recovered in hundred-fold-higher numbers from localized juvenile periodontitis lesions than from gingivitis lesions. Capnocytophaga was only recovered in approximately threefold-higher numbers from localized juvenile periodontitis than from gingivitis. The study confirms and extends previous data indicating a close relationship between A actinomycetemcomitans and localized juvenile periodontitis. It is proposed that identification of A actinomycetemcomitans may be a valuable adjunct in the diagnosis of localized juvenile periodontitis.