Increased temporal dispersion of myocardial repolarization in myotonic dystrophy type 1: beyond the cardiac conduction system

Objectives

To assess ventricular dysfunction and ventricular interaction after repair of Tetralogy of Fallot (ToF) employing echocardiography speckle-tracking and cardiac magnetic resonance imaging (CMR).

Background

Severe pulmonary regurgitation and right ventricular (RV) dysfunction are common after repair of ToF and may also affect the shape and function of the left ventricle (LV). Recent studies suggest that LV dysfunction may be of particular prognostic value.

Methods and results

Twenty-one consecutive adults with repaired ToF (15 male, mean age 38 ± 11 years, 7 with severe PR) underwent a comprehensive echocardiographic exam including speckle-tracking analysis, CMR and cardiopulmonary exercise testing. Twenty-one subjects without relevant heart disease served as controls. Echocardiographically measured RV diameters correlated with RV volumes obtained from CMR (r = 0.63; p = 0.006). In addition, a close correlation was found between RV and LV function on CMR (r = 0.74, p = 0.002), speckle-tracking LV and RV peak longitudinal 2D strain (r = 0.66, p = 0.003) and mitral and tricuspid annular plain systolic excursion (r = 0.71, p = 0.0003). While LV ejection fraction was normal in the majority of patients and not different from controls, LV longitudinal strain was significantly reduced in ToF patients (− 16.5 ± 3.3 vs. -20.5 ± 2.7%, p = 0.0001).

Conclusion

Left and right ventricular function both by CMR and speckle-tracking is interrelated in adults with repaired ToF. Despite normal LV ejection fraction, 2D longitudinal strain is significantly reduced in ToF patients, suggesting subclinical LV myocardial damage. Considering the potential prognostic value of LV dysfunction in ToF, this measurement may gain importance and should be included in future outcome studies.     

Left anterior descending coronary artery flow impaired by right ventricular apical pacing: The role of systolic dyssynchrony

Introduction

Right ventricular (RV) pacing may affect myocardial perfusion and coronary blood flow; however, it remains unknown whether this is related to systolic dyssynchrony induced by RV pacing. This prospective study was aimed to assess the relationship between dyssynchrony and the changes of coronary blood flow.

Methods

Seventy patients with sinus node dysfunction were prospectively enrolled. Coronary flow was evaluated by measuring diastolic velocity time integral (VTI) and duration at the distal-portion of left anterior descending coronary artery (LAD) with transthoracic echocardiography at baseline and follow-up. Systolic dyssynchrony was assessed with tissue Doppler imaging by time standard deviation to peak systolic velocity of 12 left ventricular segments (Ts-SD, cutoff value ≥ 33 ms).

Results

Adequate data for analysis was available from 65 patients. At follow-up (mean follow up time: 127 ± 45 days), LAD velocity-time integral (LAD-VTI: 12.1 ± 4.2 vs. 10.7 ± 4.6 cm, p < 0.001) was decreased and there was deterioration of left ventricular systolic function (left ventricular ejection fraction: 65 ± 7% vs. 62 ± 7%). However, these changes were only detected in those with RV pacing induced systolic dyssynchrony. Significant reduction of LAD-VTI (defined as ≥ 5%) occurred in 34 (52%) patients which was more prevalent in those with pacing-induced systolic dyssynchrony than those without (85.3% versus 16.1%, χ² = 31.1, p < 0.001). Though similar at baseline, LAD-VTI was significantly lower in the dyssynchrony group at follow up (p < 0.001). Cox-regression analysis showed that pacing-inducing systolic dyssynchrony [hazard ratio (HR): 3.62, p = 0.009] and higher accumulative pacing percentage (HR: 1.02, p = 0.002) were independently associated with reduction of LAD-VTI. ROC curve demonstrated that accumulative pacing percentage ≥ 35% was 97% sensitive and 84% specific in revealing significant reduction (area under the curve: 0.961, p < 0.001).

Conclusions

RV pacing induced dyssynchrony is associated with reduced coronary flow and this may account for, in part, the deleterious effect of RV pacing on ventricular function over time.     

Natural history of and risk factors for idiopathic atrial fibrillation recurrence (FAP Registry)

INTRODUCTION AND OBJECTIVES: The natural history of idiopathic atrial fibrillation is not well understood. The aim of this study was to investigate the frequency of and risk factors for disease recurrence. METHODS: The study involved 115 patients with a first episode of paroxysmal atrial fibrillation of unknown origin who were included the FAP registry, which contains data from 11 district hospitals in Catalonia, Spain. All patients underwent comprehensive clinical, laboratory, electro-cardiographic and echocardiographic investigations at baseline and were followed up periodically every 6 months to identify the occurrence of new symptomatic episodes and their complications. RESULTS: During a mean follow-up period of 912 (445) days, 32 (27.8%) patients experienced recurrence of atrial fibrillation. Those who experienced recurrence had a significantly higher left ventricular ejection fraction (P=.023) and smaller end-systolic volume (P<.001), and they were more likely to consume alcohol regularly (P=.013). Cox regression analysis confirmed that these variables had independent prognostic value. In contrast, the occurrence of syncope during the initial episode was associated with a lower likelihood of recurrence (P=.017). CONCLUSIONS: The risk of recurrence of idiopathic atrial fibrillation was high, and was enhanced by moderate alcohol consumption and increased left ventricular activity, probably of sympathetic origin. This trend was less marked in paroxysmal atrial fibrillation of vagal origin.