Relationships between left ventricular mass and QRS duration in diverse types of left ventricular hypertrophy

AIMS

Hypertrophic cardiomyopathy (HCM) may be associated with very narrow QRS, while left ventricular hypertrophy (LVH) may increase QRS duration. We investigated the relationships between QRS duration and LV mass (LVM) in subtypes of abnormal LV wall thickness.

METHODS AND RESULTS

Automated measurement of LVM on MRI was correlated to automated measurement of QRS duration on ECG in HCM, left ventricular non compaction (LVNC), left ventricular hypertrophy (LVH), and controls with healthy hearts. Uni and multivariate analyses were performed between groups including explanatory variables expected to influence LVM and QRS duration. The relationships between QRS duration and LVM were further studied within each group. Two hundred and twenty-one HCM, 28 LVNC, 16 LVH, and 40 controls were retrospectively included. Mean QRS duration was 92 ms for HCM, 104 for LVNC, 110 for LVH, and 92 for controls (P < 0.01). Mean LVM was 100, 90, 108, and 68 g/m2 (P < 0.01). QRS duration, LVM, hypertension, maximal wall thickness, and late gadolinium enhancement were significantly linked to HCM in multivariate analysis (w/wo bundle branch block). An independent negative correlation was found between LVM and QRS duration in the HCM group, while the relationship was reverse in LVNC, LVH, and controls.

CONCLUSION

QRS duration increases with LVM in LVNC, LVH, or in healthy hearts, while reverse relationship is present in HCM. These relationships were independent from other parameters. These results warrant additional investigations for refining diagnosis criteria for HCM in the future.

Precision and reproducibility of non-automatic measurement of the QRS complex in potential candidates for cardiac resynchronization therapy

BACKGROUND

Accurate measurement of QRS complex duration (QRSd) remains crucial for the selection of patients for cardiac resynchronization therapy (CRT). However, assessment of QRSd on conventional surface electrocardiograms (ECG), especially when performed without computer assistance, may be challenging due to the limited accuracy of the human eye to discriminate differences in the range of 10 ms at 25 mm/s. The value and reproducibility of visual assessment of QRSd at 25 mm/s on conventional ECGs was compared to those obtained using an electrophysiology recording system (EPRS) with simultaneous 12 lead traces at 100 mm/s, which was considered the gold standard.

METHODS

The ECGs of 102 consecutive patients with left ventricular dysfunction undergoing electrophysiological evaluation were collected. Two sets of measurements were obtained: 1) QRSd-25 measured on conventional 12-lead ECGs printed at 25 mm/s with standard amplification (10 mm/mV) by 4 different observers, and 2) QRSd-100 measured on simultaneous 12-lead traces at 100 mm/s and 40 mm/mV by 2 different observers using electronic callipers.

RESULTS

Significant differences were observed between QRSd-100 and QRSd-25 measurements (19.3 ± 9.9 ms, range 1.0-47.5, p < 0.001). QRSd-25 showed significant inter and intra-observer variability. When categorizing individual ECGs in three QRSd-25 subgroups (<120 ms, 120-149 ms and ≥150 ms), low concordance was observed between both techniques (kappa index 0.25, p < 0.001). The sensitivity and specificity of QRSd-25 to detect QRSd-100 ≥ 150 ms was 36.6% and 100.0% respectively.

CONCLUSIONS

Visual measurement of QRSd at 25 mm/s often underestimates its magnitude and presents significant inter and intraobserver variability.

Reliability and reproducibility of QRS duration in the selection of candidates for cardiac resynchronization therapy

BACKGROUND

A QRS >120 ms remains the recommended criterion for the selection of cardiac resynchronization therapy (CRT) candidates. However, the reproducibility of this measurement has not been studied thoroughly.

METHODS

QRS duration was measured by 3 experienced cardiologists and by automatic measurement on 228 electrocardiograms (ECGs) randomly collected from 188 subjects, including neonates, healthy adults, patients with complete and incomplete bundle branch block, and CRT candidates. All ECGs were recorded at a 25 mm/s sweep speed. Forty recordings were duplicated and 50 ECGs were recorded at both 25 and 50 mm/s.

RESULTS

Significant interobserver differences (P < 0.001) were found between each combination of paired observers, with an up to 50-ms absolute variability between cardiologists and low concordance with computerized measurements. Intraobserver absolute variability was also significant (P < 0.01) for the 3 observers. These significant differences persisted (P < 0.01) when focusing our interest on the ECGs in the 100-140 ms range (defined as at least one out of the 4 measures in this range). Considering the 120 ms limit, 22 (27.5%) ECGs were differently classified by at least one of the cardiologists. We observed similar interobserver differences between each combination of paired observers with a 50 mm/s sweep speed.

CONCLUSION

Manual QRS duration measurements were associated with significant inter- and intraobserver variability and low concordance with computerized measurements. The measurement of QRS is, therefore, operator-dependent and a reevaluation of the measurement methods may be essential to develop clinical and investigative standards.