What is the clinical evidence from this study?

Study design: Case-Control. Population: Obstructive Sleep Apnea Syndrome (n=85). Intervention: Obstructive Sleep Apnea Syndrome vs. No OSAS (AHI <5 events/h). Primary outcome: Fragmented QRS frequency (OR 2.842, 95% CI 1.155-6.992, p=0.021).

August 10, 2015Open Access

Presence of Fragmented QRS Complexes in Patients with Obstructive Sleep Apnea Syndrome

Q: What are the key findings of this study?

Patients with obstructive sleep apnea syndrome had a significantly higher frequency of fragmented QRS complexes compared to controls (61% vs. 35%, p=0.021).

Q: What does this research mean for the field?

Patients with obstructive sleep apnea syndrome have a significantly higher frequency of fragmented QRS complexes compared to controls. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Key Result

Patients with obstructive sleep apnea syndrome had a significantly higher frequency of fragmented QRS complexes compared to controls (61% vs. 35%, p=0.021).

Study Design

Type

Case-Control (n=85)

Blinding

Single-blind

Multicenter

Structured PICO

Population

85 participants total, including 51 patients recently diagnosed with Obstructive Sleep Apnea Syndrome (OSAS) (AHI ≥5 events/h, never received therapy, mean age 41.6 ± 10.1 years, 80% male) and 34 control volunteers without OSAS (AHI <5 events/h, mean age 43.1 ± 11.6 years, 50% male). Key exclusions: COPD, previous CPAP treatment, stage 2-3 hypertension, positive stress test, CAD/MI, LV dysfunction, LV hypertrophy, moderate-to-severe valve disease, renal/hepatic dysfunction, thyroid impairment, atrial fibrillation, dysrhythmia, pacemakers, bundle branch block, and electrolyte abnormalities.

Comparator

34 control volunteers in whom OSAS was excluded (AHI <5 events/h)

Outcome

Presence of fragmented QRS complexes and QRS duration measured on 12-lead electrocardiogramsurrogate

Patients with obstructive sleep apnea syndrome exhibit a significantly higher frequency of fragmented QRS complexes and prolonged QRS durations, suggesting subclinical myocardial changes that may be linked to increased cardiovascular risk.

Main Result

Effect estimate: OR 2.842 (95% CI 1.155-6.992)

Absolute Event Rate: 61% vs 35%

p-value: p=0.021

Limitations

Small sample size
Higher proportion of male patients in the OSAS group
ECG measurements calculated with electronic caliper and magnifying lens instead of computer-assisted methods
Lack of invasive methods like coronary angiography to rule out coronary artery disease
Sleep clinic population may not reflect the general community

Abstract

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is a disease with increasing prevalence, which is mainly characterized by increased cardiopulmonary mortality and morbidity. It is well-known that OSAS patients have increased prevalence of cardiovascular diseases including coronary heart disease, heart failure, and arrhythmias. The aim of this study was to evaluate the presence of prolonged and fragmented QRS complexes, which have previously been associated with cardiovascular mortality, in OSAS patients. METHODS: Our study included 51 patients (mean age 41.6 ± 10.1 years) who were recently diagnosed with OSAS (apnea-hypopnea index AHI ≥5 events/h) and never received therapy. The control group consisted of 34 volunteers (mean age 43.1 ± 11.6 years) in whom OSAS was excluded (AHI <5 events/h). The longest QRS complexes was measured in the 12-lead electrocardiogram (ECG) and the presence of fragmentation in QRS complexes was investigated. RESULTS: Fragmented QRS frequency was significantly higher in patients with OSAS (n = 31 61% vs. n = 12 35%, P = 0.021). QRS and QTc durations were also significantly longer in OSAS patients than controls (99.8 ± 13.9 ms vs. 84.7 ± 14.3 ms, P < 0.001; 411.4 ± 26.9 ms vs. 390.1 ± 32.2 ms, P = 0.001, respectively). Analysis of the patient and controls groups combined revealed a weak-moderate correlation between AHI and QRS duration (r = 0.292, P = 0.070). OSAS group had no correlation between AHI and QRS duration (r = -0.231, P = 0.203). CONCLUSIONS: In our study fragmented QRS frequency and QRS duration were found to increase in OSAS patients. Both parameters are related with increased cardiovascular mortality. Considering the prognostic importance of ECG parameters, it may be reasonable to recommend more detailed evaluation of OSAS patients with fragmented or prolonged QRS complexes with respect to presence of cardiovascular diseases.

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