Low urinary 6-sulphatoxymelatonin levels in patients with coronary artery disease

A decrease in nocturnal serum melatonin levels was reported in patients with clinically uncharacterized coronary artery disease. To assess whether there was a correlation between melatonin production and disease stage, we measured the nocturnal urinary excretion of 6-sulphatoxymelatonin (an index of blood melatonin concentration) in patients with chronic stable or unstable coronary disease and in a group of age-matched controls. Three groups of individuals were studied: a) 24 healthy subjects (mean age: 63 +/- 13 yr); b) 32 patients with chronic, stable, coronary disease (62 +/- 11 yr); and c) 27 patients with unstable angina (62 +/- 12 yr). For 6-sulphatoxymelatonin measurement, urine was collected from 18:00 to 06:00 hr, within 48 hr of hospitalization in the case of unstable angina. 6-Sulphatoxymelatonin was measured by a specific radioimmunoassay. Urinary 6-sulphatoxymelatonin excretion was significantly lower in unstable angina patients than in healthy subjects or in patients with stable angina. 6-Sulphatoxymelatonin correlated negatively with age in healthy subjects, but not in coronary patients. 6-Sulphatoxymelatonin excretion in patients treated with beta-adrenoceptor blockers did not differ significantly from coronary patients not receiving beta-blockers. The results indicate that patients with coronary disease have a low melatonin production rate, with greater decreases in those with higher risk of cardiac infarction and/or death.

Morbidity and mortality following early administration of amiodarone in acute myocardial infarction. GEMICA study investigators, GEMA Group, Buenos Aires, Argentina. Grupo de Estudios Multicéntricos en Argentina

AIMS

The objective of this study was to ascertain the effect of intravenous and oral amiodarone on morbidity and mortality in patients during the first hours after the onset of an acute myocardial infarction.

METHODS AND RESULTS

A cohort of 1073 patients admitted to the CCU within 24 h of the onset of symptoms of an acute myocardial infarction and heart failure (Killip and Kimball A-B) were randomized to receive amiodarone (n=542) or placebo (n=531) for 6 months. Because of the higher mortality, on an interim analysis, from a 'high dose' of amiodarone or placebo (516 patients) the protocol was changed to a 'low dose' or placebo (557 patients). Mortality with high doses of amiodarone was 16.30% vs 10.16% in the placebo group (P=0.04), whereas mortality with low doses was 6.61% vs 9.47% in the control group (P=0.20). Several non-fatal adverse effects were observed in 108 and 73 patients treated with amiodarone and placebo, respectively.

CONCLUSION

This study demonstrated that early administration of amiodarone in low doses to patients with an acute myocardial infarction may be used only if life-threatening arrhythmia justify its prescription. Conversely, when given in high doses, it might increase mortality.

A novel KCNH2 frameshift mutation (c.46delG) associated with high risk of sudden death in a family with congenital long QT syndrome type 2

Background

The congenital long QT syndrome type 2 is caused by mutations in KCNH2 gene that encodes the alpha subunit of potassium channel Kv11.1. The carriers of the pathogenic variant of KCNH2 gene manifest a phenotype characterized by prolongation of QT interval and increased risk of sudden cardiac death due to life-threatening ventricular tachyarrhythmias.

Results

A family composed of 17 members with a family history of sudden death and recurrent syncopes was studied. The DNA of proband with clinical manifestations of long QT syndrome was analyzed using a massive DNA sequencer that included the following genes: KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, ANK2, KCNJ2, CACNA1, CAV3, SCN1B, SCN4B, AKAP9, SNTA1, CALM1, KCNJ5, RYR2 and TRDN. DNA sequencing of proband identified a novel pathogenic variant of KCNH2 gene produced by a heterozygous frameshift mutation c.46delG, pAsp16Thrfs*44 resulting in the synthesis of a truncated alpha subunit of the Kv11.1 ion channel. Eight family members manifested the phenotype of long QT syndrome. The study of family segregation using Sanger sequencing revealed the identical variant in several members of the family with a positive phenotype.

Conclusions

The clinical and genetic findings of this family demonstrate that the novel frameshift mutation causing haploinsufficiency can result in a congenital long QT syndrome with a severe phenotypic manifestation and an elevated risk of sudden cardiac death.

Prevalence of Cardiac Arrhythmias and Distal Conduction Disorders in Patients With Chronic Chagas' Disease and Elevated Autoantibodies Against M2 Muscarinic Acetylcholine Receptors

Chagas' disease (ChD) is a parasitic disease endemic to regions of Latin America and with an increasingly global reach. Up to 30% of patients with ChD develop severe dilated cardiomyopathy, ventricular arrhythmias, conduction disorders and/or sudden cardiac death. Autoantibodies against M₂ muscarinic acetylcholine receptors (M₂ mAChR) have been implicated in the pathogenesis of ChD. We sought to understand whether there was an association between anti-M₂ mAChR autoantibody titers in patients with chronic ChD and the presence of distal cardiac conduction disorders or cardiac arrhythmias. We conducted a cross-sectional study in 79 patients from Argentina and Bolivia with chronic ChD without evident structural heart disease. Autoantibody titers were measured using indirect enzyme-linked immunosorbent assay. Elevated anti-M₂ mAChR autoantibody titers were associated with the presence of distal conduction disease but not with cardiac arrhythmias. High anti-M₂ mAChR autoantibody levels could assist with identifying early structural heart disease in patients with chronic ChD.

[Different phenotypes of mitral regurgitation in patients with right apical ventricular pacing: an echocardiographic approach in a heterogeneity of clinical scenarios]

The presence of mitral regurgitation (MR) in patients with right ventricular apical pacing can be the result of multiple phenomena. On the one hand, this stimulation causes an asynchronous activation of the left ventricle (LV) and the papillary muscles, leading to a deterioration of the LV ejection fraction and causing an inadequate closure of the valve apparatus. However, there is a wide heterogeneity of ischemic and non-ischemic myocardial conditions that can coexist with mechanical alteration of the LV and the mitral valve leading to or worsening MR in these patients, which can make the etiological determination of valvular regurgitation difficult. Transthoracic echocardiography study allows comprehensive evaluation of mitral valve regurgitation and ventricular function parameters and mechanical asynchrony as a result of artificial pacing. The comprehensive study of these phenomena is relevant in clinical decision-making to define those patients who benefit from cardiac resynchronization therapy to alleviate symptomatic MR.

Insights of tricuspid regurgitation mechanisms in patients with right ventricular apical pacing by three-dimensional echocardiography

OBJECTIVE

Device lead-induced tricuspid regurgitation (LITR) mechanisms are well-defined by 3D transthoracic echocardiography (3D-TTE). There is a lack of data on the Latin-American population. The objective of this study was to describe the prevalence of several mechanisms and insights in patients with permanent right ventricular (RV) implanted devices by 3D-TTE examination.

METHODS

We performed a cross-sectional analysis of 101 patients with permanent cardiac devices such as pacemakers or defibrillators. 3D-TTE was obtained on all patients in RV-focused apical views to perform a complete tricuspid valve (TV) evaluation: leaflets, subvalvular apparatus, precise lead location, and functional assessment to evaluate possible mechanisms of tricuspid regurgitation (TR).

RESULTS

In a total of 101 patients, the leads did not interfere with TV function in 53 p. (59%), while LITR was observed in 38 (41%) patients. Adherent, impinging, entangled, and mixed lead-induced mechanisms were observed. Time in years since device implantation was significantly higher in patients with LITR.

CONCLUSIONS

LITR was present in a high proportion of our population. LITR is the result of damage to the TV as well as its subvalvular apparatus due to the fibrotic and inflammatory response over time when leads are situated in unfavorable locations.

3D-Echocardiography in the assessment of lead-induced tricuspid regurgitation

Background

Lead-induced tricuspid regurgitation (LITR) is caused by several mechanisms that can be assessed by 3D-Echocardiography (3DE). Its prevalence was not studied to date in the Latin-American series.

Purpose

To determine prevalence and mechanisms of LITR in a series of patients with permanent cardiac devices by 3DE.

Methods

We perform a cross-sectional analysis of 101 patients with permanent cardiac devices as pacemakers or defibrillators. Transthoracic 3DE was obtained on all patients in RV-focused apical views to perform a complete tricuspid valve leaflets, subvalvular apparatus, lead placement and functional assessment to evaluate possible mechanisms of tricuspid regurgitation.

Results

Of a total of 101 patients, lead visualization was possible in 88%. In 59% lead was in commissural position and did not interfere with tricuspid leaflet mobility. Nevertheless, in 41% LITR was observed by several mechanisms. Leaflet impingement was the most prevalent cause in 30,7% causing valve leaflet interference and organic damage. Catheter adherence and/or entrapment to the leaflet or the tricuspid subvalvular apparatus was present in 10.3%. Two patients seem to have leaflet perforation by the catheter as the main mechanism; however, a further assessment was not possible. Patients with LITR had higher time since catheter implantation, lower left ventricular ejection fraction, more severity of tricuspid regurgitation, and right ventricular dilatation.

Conclusions

3DE enables to the identification of 41% of patients with LITR and leaflet impingement was the most prevalent mechanism. LITR patients had more time since cardiac device implantation. Some unfavorable catheter locations on the tricuspid valve can have some influence on the development of LITR over time.

Funding Acknowledgement

Type of funding sources: None.