Dysglycemia and arrhythmias

Disorders in glucose metabolism can be divided into three separate but interrelated domains, namely hyperglycemia, hypoglycemia, and glycemic variability. Intensive glycemic control in patients with diabetes might increase the risk of hypoglycemic incidents and glucose fluctuations. These three dysglycemic states occur not only amongst patients with diabetes, but are frequently present in other clinical settings, such as during critically ill. A growing body of evidence has focused on the relationships between these dysglycemic domains with cardiac arrhythmias, including supraventricular arrhythmias (primarily atrial fibrillation), ventricular arrhythmias (malignant ventricular arrhythmias and QT interval prolongation), and bradyarrhythmias (bradycardia and heart block). Different mechanisms by which these dysglycemic states might provoke cardiac arr-hythmias have been identified in experimental studies. A customized glycemic control strategy to minimize the risk of hyperglycemia, hypoglycemia and glucose variability is of the utmost importance in order to mitigate the risk of cardiac arrhythmias.

Therapeutic Inefficacy and Proarrhythmic Nature of Metoprolol Succinate and Carvedilol Therapy in Patients With Idiopathic, Frequent, Monomorphic Premature Ventricular Contractions

BACKGROUND

Antiarrhythmic drugs remain the first-line therapy for treatment of idiopathic ventricular arrhythmias.

STUDY QUESTION

The aim of this study was to assess the therapeutic efficacy of extended-release metoprolol succinate (MetS) and carvedilol for idiopathic, frequent, monomorphic premature ventricular contractions (PVCs).

STUDY DESIGN

Study population consisted of 114 consecutive patients: 71 received MetS and 43 received carvedilol.

MEASURES AND OUTCOMES

All patients underwent 24-hour Holter monitoring at baseline and during drug therapy. PVC-burden response to drug therapy was categorized as "good" (≥80% reduction), "poor" (either <80% reduction or ≤50% increase), and "proarrhythmic" responses (>50% increase) based on change in PVC burden compared with baseline.

RESULTS

Most common presenting symptom was palpitations (65.8%), followed by coincidental discovery (29%). The mean MetS and carvedilol dosages were 65.57 ± 30.67 mg/d and 23.66 ± 4.26 mg/d, respectively. "Good," "poor," and "proarrhythmic" responses were observed in 11.3% and 16.3%, 63.4% and 67.4%, and 25.3% and 16.3% of patients treated with MetS and carvedilol, respectively. In patients with relatively high (≥16%) PVC burden, the sum of "poor"/"proarrhythmic" response was observed in 95.5% and 86.4% of patients treated with MetS and carvedilol, respectively. "Proarrhythmic" response was observed in 21.9% of the patients, particularly in the presence of relatively lower (≤10%) baseline PVC burden. Patients with "good" response during beta-blocker therapy had higher baseline daily average intrinsic total heart beats compared with patients with "poor"/"proarrhythmic" response combined (96,437 ± 26,488 vs. 86,635 ± 15,028, P = 0.047, respectively). Side effects and intolerance were observed in 5.6% and 18.6% of patients treated with MetS and carvedilol, respectively.

CONCLUSIONS

MetS and carvedilol for idiopathic, frequent, monomorphic PVCs are frequently inefficient. Therapeutic efficacy decreases further in patients with relatively high (≥16%) PVC burden. Relatively higher baseline daily intrinsic total heart beats may be used to predict "good" response before beta-blocker therapy.

EHRA research network surveys: 6 years of EP wires activity

Clinical practice should follow guidelines and recommendations mainly based on the results of controlled trials, which are often conducted in selected populations and special conditions, whereas clinical practice may be influenced by factors different from controlled scientific studies. Hence, the real-world setting is better assessed by the observational registries enrolling patients for longer periods of time. However, this may be difficult, expensive, and time-consuming. In 2009, the Scientific Initiatives Committee of the European Heart Rhythm Association (EHRA) has instigated a series of surveys covering the controversial issues in clinical electrophysiology (EP). With this in mind, an EHRA EP research network has been created, which included EP centres in Europe among which the surveys on 'hot topic' were circulated. This review summarizes the overall experience conducting EP wires over the past 6 years, categorizing and assessing the topics regarding clinical EP, and evaluating the acceptance and feedback from the responding centres, in order to improve participation in the surveys and better address the research needs and aspirations of the European EP community.

Asymptomatic ventricular premature depolarizations are not necessarily benign

AIMS

Most patients with idiopathic ventricular premature depolarizations (VPDs) complain of symptoms related to this arrhythmia, but some patients are asymptomatic even with a high VPD burden. Our understanding of the relationship between symptoms and cardiomyopathy related to this arrhythmia remains limited.

METHODS AND RESULTS

We evaluated 801 subjects (381 men; mean age, 55 ± 17 years) who visited our outpatient clinic. All subjects were diagnosed with frequent VPDs (1% or >1000 beats/day). The patients were divided into two groups according to the presence or absence of typical VPD symptoms (palpitations or skipped beats during VPDs): symptomatic patients (n = 455) and asymptomatic patients (n = 346). Clinical and electrocardiogram parameters were compared between these two groups. In the symptomatic group, palpitations were the most frequent symptom (91%). Daily VPD burden (P = 0.90) and electrocardiogram parameters (P>0.05) did not differ significantly between groups. The incidence of frequent VPDs with left ventricular dysfunction was significantly higher in the asymptomatic group (symptomatic patients, 3.0%; asymptomatic patients, 10.5%; P < 0.001).

CONCLUSION

The absence of typical VPD-related symptoms may be a risk factor for cardiomyopathy and be associated with an adverse outcome.