The purpose of this study was to compare the diagnostic sensitivity of 1-day Holter monitoring versus 7-day Holter monitoring (7DH) to detect atrial and ventricular arrhythmias in a population of stable patients with chronic heart failure and left ventricular dysfunction. Sixty-three consecutive stable patients with chronic heart failure with left ventricular ejection fractions ≤50% were included. Blood samples were obtained, the Minnesota Living With Heart Failure Questionnaire was administered, and echocardiography, 6-minute walk tests, and 7DH were performed at enrollment. The mean ejection fraction was 35.8 ± 9.8%, and the mean age was 55.5 ± 13.9 years. Seven-day Holter monitoring did not significantly increase the detection of nonsustained atrial tachycardia or atrial fibrillation. In contrast, the incidence of nonsustained ventricular tachycardia increased in nonischemic patients from 35.1% on day 1 to 54.1% on day 7 (p = 0.01). In ischemic patients, the sensitivity increased from 11.5% to 46.2% (p = 0.004). Two patients without nonsustained ventricular tachycardia on day 1 had episodes of 13 and 16 beats on days 3 and 6 of monitoring. In patients with left ventricular ejection fractions >35% and N-terminal–pro-brain natriuretic peptide levels <1,000 pg/ml, no episodes of nonsustained ventricular tachycardia were detected on day 1 in nonischemic and ischemic patients, but 7DH detected 3 new patients in each group. In conclusion, 7DH clearly improves the detection and allows a better characterization of ventricular arrhythmic episodes but seems to be less useful for supraventricular events.
The purpose of this study was to compare the diagnostic sensitivity of 1-day Holter monitoring (1DH) versus 7-day Holter monitoring (7DH) to detect atrial and ventricular arrhythmias in a population of stable patients with chronic heart failure (CHF) and systolic dysfunction in ischemic versus nonischemic cardiomyopathy.
Methods
The study was carried out following the principles of the Declaration of Helsinki. It was approved by the local ethics committee, and written informed consent was obtained from each patient. Patients were recruited during scheduled outpatient visits to cardiology heart failure outpatient clinic at our center. From September 2007 to February 2008, 63 consecutive patients with established diagnoses of stable CHF met eligibility criteria and gave written informed consent to participate. All patients had ejection fractions (EFs) ≤50% and were clinically stable, without need for hospital admission or intravenous vasoactive agents. Exclusion criteria included age <18 years and serious co-morbid conditions with associated life expectancy <1 year. Hospitalization for myocardial infarction, unstable angina, or heart failure within the past 3 months and any cardiac revascularization procedure <30 days before enrollment were also exclusion criteria.
Data on demographic and clinical characteristics, medications, and laboratory parameters were acquired at enrollment. Risk factors were defined as follows: hypertension (elevated systolic pressure >140 mm Hg or diastolic blood pressure >90 mm Hg or the use of antihypertensive drugs), hypercholesterolemia (low-density lipoprotein cholesterol >160 mg/dl, lipid-lowering medication use, or dietary control) and diabetes mellitus (all patients with fasting plasma glucose >126 mg/dl or receiving antidiabetic therapy). All subjects underwent 12-lead electrocardiography, chest x-rays, and 6-minute walk tests according to standardized procedures. The Minnesota Living With Heart Failure Questionnaire was administered and 7DH performed at enrollment. Echocardiography was also performed (Sonos 7500; Philips Medical Systems, Andover, Massachusetts), and standardized projections and measurements were made for chamber quantification. The left ventricular EF was calculated using Simpson’s biplane method. All patients received standard management as recommended by contemporary guidelines.
Ambulatory 7-day, 3-channel electrocardiographic recordings with x-y-z orthogonal leads were obtained using a commercially available device (Lifecard CF; Del Mar Reynolds, Issaquah, Washington). The raw electrocardiographic data, stored in a proprietary format, were exported to the International Society for Holter and Noninvasive Electrocardiology standard using custom-made software in accordance with the specifications provided by the manufacturer. To improve the accuracy of the QRS template classification and preliminary Holter analysis, data were split into 7 pieces and processed using standard Holter analysis software (ELA Medical, Sorin Group, Paris, France). A visual check of the QRS complex classification and every arrhythmic event was performed by a trained cardiologist, and manual corrections were made as needed. Nonsustained atrial tachycardia (NSAT) was defined as ≥3 consecutive premature normal beats at >120 beats/min and nonsustained ventricular tachycardia (NSVT) as ≥3 consecutive ventricular premature beats at >120 beats/min.
Continuous variables were tested for a normal distribution using the Kolmogorov-Smirnov test. Normally distributed data are presented as mean ± SD and non-normally distributed data as medians with interquartile ranges. Categorical variables are expressed as percentages. Student’s t test (impaired data) or the Mann-Whitney U test if appropriate was used to compare continuous variables, and the chi-square test was used for categorical variables. McNemar’s test was used to compare the percentage of events (supraventricular or ventricular) between day 1 and the end of the monitoring period (days 1 to 7). We also examined the presence of NSVT, comparing day 1 to days 1 to 7 according to the EF and N-terminal–pro-brain natriuretic peptide (NT-proBNP) levels. We used a cut-off point of 35% for the left ventricular EF and 1,000 pg/ml for NT-proBNP because these values have been associated with increased morbidity and mortality in stable patients with CHF. Data were processed using SPSS version 13 (SPSS, Inc., Chicago, Illinois). A p value <0.05 was considered statistically significant.
Results
Sixty-three patients were enrolled in the study. The mean age was 55.5 ± 13.9 years, and 88.8% were men. The mean EF was 35.8 ± 9.8%, and 71.4% of patients were in New York Heart Association class II. Table 1 lists baseline demographics and clinical characteristics in ischemic and nonischemic patients. Ischemic patients were older and had a higher prevalence of diabetes, hypertension, and hypercholesterolemia.
