Interatrial Block Predicts Life‐Threatening Arrhythmias in Dilated Cardiomyopathy

Figure 1. Patient selection for this retrospective analysis performed within the Maastricht Dilated Cardiomyopathy Registry. All patients presented between 2004 and 2017 at the DCM outpatient clinic (OC) in the Maastricht University Medical Center. *Baseline ECG: ECG closest to OC (at the latest 1 month before or after OC). AF indicates atrial fibrillation; DCM, dilated cardiomyopathy; and IAB, interatrial block.

Figure 2. Kaplan–Meier curves of survival free of life‐threatening arrhythmias performed within the Maastricht Dilated Cardiomyopathy cohort. A, stratified by No interatrial block (IAB), IAB, and Atrial Fibrillation (AF). The survival distribution between the groups was significantly different (P=0.003, χ 2=11.5). This difference was significantly different for both IAB or AF vs No IAB (P=0.006 and P=0.001, respectively), but not for IAB vs AF (P=0.999) after applying Bonferroni correction. B, stratified by No interatrial block (IAB), Partial IAB, Advanced IAB, and Atrial Fibrillation (AF). The survival distribution between the groups was significantly different (P=0.006). This difference was significantly different for Partial IAB, Advanced IAB or AF vs No IAB (P=0.032 and P=0.005, 0.003, respectively), but not for Partial IAB vs Advanced IAB (P=0.999) after applying Bonferroni correction.

Figure 3. Univariable overview of hazard ratios (HR) for the study end point (life‐threatening arrhythmias). ACEi indicates angiotensin‐converting enzyme inhibitor; AF, atrial fibrillation; ARB, angiotensin receptor blocker; BMI, body mass index; bpm, beats per minute; DBP, diastolic blood pressure; DCM, dilated cardiomyopathy; DM, diabetes; FH CMP, self‐reported family history of cardiomyopathy; HFH, heart failure hospitalization; HR, heart rate; IAB, inter‐atrial block; LAVI, left atrial volume index; LVEDDI, left ventricular end‐diastolic diameter indexed by body surface area; LVEF, left ventricular ejection fraction; LVH, left ventricular hypertrophy (LVMI≥95 in female patients or LVMI≥115 in male patients); LVMI, left ventricular mass indexed by body surface area; MRA, mineralocorticoid receptor antagonist; NT‐proBNP, N‐terminal‐pro hormone Brain Natriuretic Peptide; NYHA, New York Heart Association classification; OMT, percentage of optimal medical heart failure therapy in line with the ESC 2016 guidelines 5 ; ref, reference; and SBP, systolic blood pressure.

Figure 4. Multivariable overview (applying backward selection) of hazard ratios (HR) for the study end point (life‐threatening arrhythmias). A, P‐morphology stratified as No IAB (PWD≤120 ms), IAB (PWD>120 ms), or AF. B, P morphology stratified as No IAB (PWD≤120 ms), Partial IAB (PWD>120 ms), Advanced IAB (PWD>120 ms AND biphasic morphology of P‐wave in leads II, III and aVF as previously described 14 ; patients with biphasic morphology of P‐wave in at least III and aVF were also included in this group) or AF. AF indicates atrial fibrillation; FH CMP, self‐reported family history of dilated cardiomyopathy; IAB, inter‐atrial block; LVH, left ventricular hypertrophy (LVMI≥95 in female patients or LVMI≥115 in male patients); PWD, P‐wave duration; and ref, reference.

Figure 5. Kaplan–Meier curves of survival free of life‐threatening arrhythmias performed within the Utrecht Cardiomyopathy cohort (UNRAVEL). A, stratified by No interatrial block (IAB), IAB, and atrial fibrillation (AF). The survival distribution between the groups was significantly different (P=0.008, χ 2=9.7). This difference was significantly different for both IAB or AF vs No IAB (P=0.037 and P=0.005, respectively), but not for IAB vs AF (P=0.836) after applying Bonferroni correction. B, stratified by No interatrial block (IAB), Partial IAB, Advanced IAB and AF. The survival distribution between the groups was significantly different (P=0.004). This difference was significantly different for Advanced IAB or AF vs No IAB (P=0.009 and P=0.010, respectively), but not for Partial IAB vs No IAB (P=0.211) and Partial vs Advanced IAB (P=0.473), after applying Bonferroni correction.

Figure 6. Interatrial block (IAB) and atrial fibrillation (AF) assessed at baseline ECG confer similar increased risk of life‐threatening arrhythmias (LTAs) in ambulant patients with dilated cardiomyopathy (DCM) in 2 independent cohorts (The Maastricht DCM Cohort and The Utrecht Cardiomyopathy Cohort, UNRAVEL). The survival distribution was significantly different for the 3 groups in both cohorts (P=0.003 Maastricht; P=0.008 Utrecht). This difference was significantly different for both IAB and AF vs No IAB, but not for IAB vs AF. *=monophasic P‐wave;**=bi‐phasic P‐wave. PWD indicates P‐wave duration.