Spontaneous variability in ventricular ectopic activity during chronic antiarrhythmic therapy

Repeatability of ectopic beats from 48-hr ambulatory electrocardiography: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

The purpose of this study was to characterize the repeatability of ectopic beats, defined by premature atrial contractions (PACs) and premature ventricular contractions (PVCs), on ambulatory electrocardiogram (aECG) monitoring and evaluate the effect of length of aECG monitoring on the repeatability estimates.

METHODS

This analysis includes 95 randomly selected participants from the Atherosclerosis Risk in Communities Study (ARIC; 2011-2013). The participants wore a Holter monitor for two, 48-hr periods separated by a mean of 38 days following an identical, standardized protocol. We divided each 48-hr recording into 3-, 6-, 12-, and 24-hr recording periods and calculated intraclass correlation coefficients (ICCs) for PACs and PVCs and also as a percentage of the corresponding total of recorded beats per hour among these periods.

RESULTS

All participants had ≥1 PAC during the 48-hr recordings, and only two participants had no PVCs. ICCs were >0.83 for all indices and recording lengths ≥12 hrs. ICCs were intermediate for 6-hr recordings (range 0.80-0.83) and lower for 3-hr recordings (range 0.74-0.80). The ratio of the between- to within-participant variation increased with recording length.

CONCLUSION

Repeatability of PACs and PVCs was excellent for recording lengths of 6-24 hr and fair for 3 hr. Repeatability varies over shorter duration recordings within the 48-hr recording period, and thus the present results have implications for detection algorithms for ectopic beats and can facilitate epidemiologic and clinical applications in which knowledge of measurement variability and misclassification are needed.

Losartan decreased premature ventricular contractions in patients with hypertension

Losartan, enalapril and amlodipine reduced the number of premature ventricular contractions (PVCs) in patients with essential hypertension as well as blood pressure. The effect of losartan was the most prominent among the three drugs.

Effect of continuous positive airway pressure on ventricular ectopy in heart failure patients with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) elicits a number of cardiovascular perturbations that could lead acutely or chronically to increased ventricular ectopy in patients with heart failure (HF). We tested the hypothesis that treatment of OSA with continuous positive airway pressure (CPAP) in patients with HF would reduce the frequency of ventricular premature beats (VPBs) during sleep in association with reduced sympathetic nervous system activity.

METHODS

Following optimisation of medical treatment, 18 HF patients with OSA and >10 VPBs per hour of sleep were randomised to a control group (n = 8) or a treatment group who received CPAP (n = 10). The frequency of VPBs and urinary norepinephrine (noradrenaline) concentrations during total sleep time were determined at baseline and after 1 month.

RESULTS

Control patients did not experience any significant changes in apnoea-hypopnoea index (AHI), mean nocturnal O(2) saturation, or the frequency of VPBs. In contrast, there was a significant reduction in AHI (p<0.001), an increase in minimum O(2) saturation (p = 0.05), a reduction in urinary norepinephrine concentrations (p = 0.009), and a 58% reduction in the frequency of VPBs during total sleep (from mean (SE) 170 (65) to 70 (28) per hour, p = 0.011) after 1 month of CPAP treatment.

CONCLUSIONS

In patients with HF, treatment of co-existing OSA by CPAP reduces the frequency of VPBs during sleep. These data suggest that reductions in VPBs and other ventricular arrhythmias through treatment of OSA might improve the prognosis in patients with HF.

Correlation and stability of heart rate and ventricular ectopy variability in patients with congestive heart failure

The stability of indexes of heart rate variability and their possible association with spontaneous variability of ventricular ectopy was examined in 13 patients with advanced congestive heart failure over 14 consecutive days of 24-hour ambulatory electrocardiographic recording. It was found that time and frequency domain measures of heart rate variability are stable over time and are inversely correlated with spontaneous variability of ventricular ectopy.

Pharmacokinetics of pirmenol enantiomers and pharmacodynamics of pirmenol racemate in patients with premature ventricular contractions

The pharmacokinetics and pharmacodynamics of pirmenol were investigated in 12 patients with premature ventricular contractions (PVCs) after oral administration of racemic pirmenol, 100 mg and 200 mg every 12 hours. Holter monitoring was performed and serial blood samples were collected after the seventh doses. Plasma concentrations of pirmenol enantiomer were determined using a stereospecific liquid chromatographic assay. Clearance of total (-)-pirmenol was 20% higher than that of total (+)-pirmenol, and the difference in unbound clearance was 45% between enantiomers. Total pirmenol showed a smaller difference because of stereoselective protein binding, with 25% (100-mg dose) or 27% (200-mg dose) higher fraction unbound for (+)-pirmenol than for (-)-pirmenol. Distribution volume was similar for both enantiomers. Dose-dependent clearance was observed for unbound pirmenol enantiomers, as both enantiomers showed 20% lower unbound clearance at the higher dose. Antiarrhythmic effect (% reduction in PVCs from baseline) was correlated with plasma concentrations of pirmenol using a sigmoid maximum drug effect model, and patients showed a large variability in their antiarrhythmic response to plasma concentrations of pirmenol. The median value for minimum effective plasma concentration of racemic pirmenol was 1.5 micrograms/mL.

Loss of efficacy during long-term cifenline therapy: development of antiarrhythmic resistance?

OBJECTIVE

To describe the possible development of antiarrhythmic resistance to cifenline, an investigational Class I agent.

METHODS

Forty patients with chronic ventricular premature depolarizations (VPDs) underwent dose-ranging studies with cifenline, an investigational Class I antiarrhythmic agent. Patients had a minimum of 30 VPDs/h detected by ambulatory electrocardiographic (ECG) monitoring over a 48-hour baseline placebo lead-in period. Twenty-two patients (55 percent) who initially responded received long-term cifenline therapy. Ambulatory ECG monitoring over 24 hours was repeated during active cifenline therapy at three-month intervals and during placebo reintroduction at six-month intervals.

RESULTS

After an average follow-up of 28 months, VPD frequency during cifenline therapy was similar to that during initial baseline placebo therapy in 8 of the 22 patients (36 percent) who initially responded. Placebo reintroduction following cifenline failure showed a VPD frequency similar to that with active therapy. All patients had further cifenline dosage increases without success. Plasma cifenline concentrations increased in all patients and were in the high therapeutic range. All 8 patients were switched to other Class I antiarrhythmic agents with successful VPD suppression during treatment with the first alternative drug.

CONCLUSIONS

We conclude that antiarrhythmic resistance occurred with cifenline in these patients as (1) initial efficacy was established for a minimum of two years, (2) VPD frequency was similar during cifenline therapy and placebo reintroduction, (3) cifenline therapy failure continued despite further dosage titration, and (4) alternative Class I antiarrhythmic therapy was successful in all patients. Repeat intermittent ambulatory ECG monitoring is necessary not only to assess the continued need for antiarrhythmic drug therapy, but also to establish continued long-term efficacy.