Regression of fragmented QRS complex: a marker of electrical reverse remodeling in cardiac resynchronization therapy

Tighter is better: Can a simple and cost-free parameter predict response to cardiac synchronization therapy?

BACKGROUND

Several studies have evaluated the role of QRS duration (QRSd) or QRS narrowing as a predictor of response to cardiac resynchronization therapy (CRT) to reduce nonresponders.

AIM

Our study aimed to determine the correlation between the relative change in QRS index (QI) compared to clinical outcome and prognosis in patients who underwent CRT implantation.

METHODS

A three-centers study involving 398 patients with a CRT device was conducted. Clinical, echocardiographic and pharmacological variables, QRSd before and after CRT implantation and QI were measured.

RESULTS

In a 6-month follow-up, a significant improvement in left ventricular ejection fraction (LVEF), left ventricular end-diastolic and systolic volumes (LVEDV and LVESV) were observed. QI was related to reverse remodeling (multiple r-squared: 0.48, adjusted r-squared: 0.43, p = .001), and the cut-off value that best predicted LV reverse remodeling after 6 months of CRT was 12.25% (AUC 0.7, p = .001). At 24 months, a statistically significant difference was found between patients with a QI ≤ 12.25% and those with a QI > 12.25% regarding NYHA class worsening (p = .04). The mean of the QI of patients who died from cardiovascular causes was lower than patients who died of other causes (p = .0179). A correlation between pre-CRT QRSd/LVEDV and QI was observed (r = + 0.20; p = .0003). A higher QRSd/LVEDV ratio was associated with an improved LVEF, LVEDV, and LVESV (p < .0001) at follow-up.

CONCLUSIONS

QI narrowing after CRT was related to greater echocardiographic reverse remodeling and a lower rate of adverse events (death or cardiovascular hospitalizations). The QI can improve the prediction of adverse events in a population with CRT regardless of comorbidities according to the Charlson Comorbidity Index. QI could be used to predict CRT response.

Fragmented QRS complex is a prognostic marker of microvascular reperfusion and changes in LV function occur in patients with ST elevation myocardial infarction who underwent primary percutaneous coronary intervention

The present study aimed to investigate the in-hospital and long-term prognostic value of fragmented QRS complex (fQRS) for microvascular reperfusion and changes in left ventricular (LV) function in patients with ST elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI). A total of 216 patients with STEMI undergoing primary PCI were included in the current study. Patients were divided into two groups based on the presence (n=126) or absence (n=90) of fQRS following electrocardiograms (ECGs) on admission. Following primary PCI and follow up, patients were divided into four groups based on new onset, resolution, persistence and absence of fQRS. Major adverse cardiac events were defined to include cardiovascular death, arrhythmia, heart failure, reinfarction and target vessel revascularization. The percentage of patients with heart failure and microvascular reperfusion differed significantly between the fQRS(+) and fQRS(−) groups. Levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), Peak creatine kinase-MB (CK-MB) and Troponin I levels were observed to be significantly higher in the fQRS(+) group compared with the fQRS(−) group. In univariate logistic regression analysis, left ventricular ejection fraction (LVEF), NT-proBNP, Troponin I, Peak CK-MB and microvascular reperfusion were found to be associated with fQRS. Multivariate analysis identified that LVEF, NT-proBNP, Troponin I and microvascular reperfusion may be independent predictors of fQRS. The presence of fQRS was demonstrated to be associated with left ventricular dysfunction at follow up assessments. The presence of fQRS was not only significantly associated with myocardial microvascular reperfusion and left ventricular function, but was also a prognostic marker in STEMI.

Magnitude of QRS duration reduction after biventricular pacing identifies responders to cardiac resynchronization therapy

BACKGROUND

Several studies have investigated the association between native QRS duration (QRSd) or QRS narrowing and response to biventricular pacing. However, their results have been conflicting. The aim of our study was to determine the association between the relative change in QRS narrowing index (QI) and clinical outcome and prognosis in patients who undergo cardiac resynchronization therapy (CRT) implantation.

METHODS AND RESULTS

We included 311 patients in whom a CRT device was implanted in accordance with current guidelines for CRT. On implantation, the native QRS, the QRSd and the QI during CRT were measured. After 6months, 220 (71%) patients showed a 10% reduction in LVESV. The median [25th-75th] QI was 14.3% [7.2-21.4] and was significantly related to reverse remodeling (r=+0.22; 95%CI: 0.11-0.32, p=0.0001). The cut-off value of QI that best predicted LV reverse remodeling after 6months of CRT was 12.5% (sensitivity=63.6%, specificity=57.1%, area under the curve=0.633, p=0.0002). The time to the event death or cardiovascular hospitalization was significantly longer among patients with QI>12.5% (log-rank test, p=0.0155), with a hazard ratio (HR) of 0.3 [95%CI: 0.11-0.78]. In the multivariate regression model adjusted for baseline parameters, a 10% increment in QI (HR=0.61[0.44-0.83], p=0.002) remained significantly associated with CRT response.

CONCLUSIONS

Patients with a larger decrease in QRSd after CRT initiation showed greater echocardiographic reverse remodeling and better outcome from death or cardiovascular hospitalization. QI is an easy-to-measure variable that could be used to predict CRT response at the time of pacing site selection or pacing configuration programming.

Usefulness of notched duration to predict response to cardiac resynchronization therapy

OBJECTIVES

The presence of notches in the biventricular paced QRS complex (BiP-QRS) from the posterolateral cardiac vein displays delays in the activation of the left ventricle and may consequently be linked with longer times of stimulus conduction. Our objective was to determine the relationship between the notch duration ≥ 0.1 mV in the BiP-QRS and the effectiveness of cardiac resynchronization therapy (CRT).

DESIGN

A total of 210 patients, who underwent de novo CRT implantation previously and had ≥ 1 follow-up between August 2009 and February 2014, were enrolled in the study. Echocardiographic response to CRT was defined as "an increase of ≥ 5% in ejection fraction" and clinical response to CRT was defined as "an improvement ≥ 1 in New York Heart Association class without heart failure hospitalization after 6 months of CRT implantation."

RESULTS

At a mean follow-up of 9.2 ± 2.1 months, 142 patients (67%) were classified as responders to CRT. BiP-QRS duration was significantly longer among non-responders compared with responders (p = 0.036). More of the non-responders have notched in their BiP-QRS than responders (63% vs. 40%, p = 0.002). Median duration of notch was significantly higher among non-responders (80 ms vs. 67.5 ms, p = 0.041). Notch duration > 67.5 ms was associated with 2.8 times higher non-response to therapy (odds ratio: 2.8; 95% confidence interval: 1.075-7.588, p = 0.035).

CONCLUSIONS

Patients with notch duration greater than 67.5 ms are associated with poor response to CRT. Notch duration > 67.5 ms predicts non-response to therapy with 50.0% specificity and 72.1% sensitivity.

QRS fragmentation and sudden cardiac death in the obese and overweight

Background

Obesity has been associated with significantly greater risk of sudden cardiac death (SCD); however, identifying the obese patient at highest risk remains a challenge. We evaluated the association between QRS fragmentation on the 12‐lead electrocardiogram and SCD, in obese/overweight subjects.

Methods and Results

In the ongoing prospective, community‐based Oregon Sudden Unexpected Death Study (population approximately 1 million), we performed a case‐control analysis, comparing obese/overweight SCD victims with obese/overweight controls from the same geographic region. Archived ECGs prior and unrelated to the SCD event were used for cases and all ECG measurements were assessed in blinded fashion. Fragmentation was defined as the presence of RSR’ patterns and/or notching of the R/S wave in at least 2 contiguous leads. Analysis was limited to ECGs with QRS duration <120 ms. Overall prevalence of fragmentation was higher in cases (n=185; 64.9±13.8 years; 67.0% male) compared with controls (n=405; 64.9±11.0 years; 64.7% male) (34.6% versus 26.9%, P=0.06). Lateral fragmentation was significantly more frequent in cases (8.1% versus 2.5%; P<0. 01), with non‐significant differences in anterior and inferior territories. Fragmentation in multiple territories (≥2) was also more likely to be observed in cases (9.7% versus 4.9%, P=0.02). In multivariable analysis with consideration of established SCD risk factors, lateral fragmentation was significantly associated with SCD (OR 2.84; 95% CI 1.01 to 8.02; P=0.05).

Conclusion

QRS fragmentation, especially in the lateral territory is a potential risk marker for SCD independent of the ejection fraction, among obese/overweight subjects in the general population.