Pathophysiology of heart failure with normal ejection fraction (HFNEF) is still poorly understood. We identified 7 patients with HFNEF associated with interatrial block (IAB) and a particular Doppler mitral inflow pattern.

The patients were selected during the past 2 years, because they had severe HFNEF, and a short, abruptly terminated mitral A wave. We analyzed their echo-Doppler, hemodynamic and electrophysiologic features.

There were 1 male and 6 female patients, mean age was 75±7. Pulsed wave mitral Doppler was restrictive and triphasic, including high velocity E wave, a mid-diastolic “L” wave, and a delayed and shortened A wave (figure). Mean E/A and E/E’ ratios were 3.7±1.3 and 23±4, respectively. Mean mitral A wave duration was 98±15ms compared to 170±24ms at the tricuspid valve (p=0,001). TDI study of A’ at the lateral tricuspid and mitral annulus showed an interatrial mechanical delay of 110±43ms. Catheterization showed severe postcapillary pulmonary hypertension: mean pulmonary artery pressure 44±7, wedge pressure 26±5 with a V wave of 49±11mmHg. Electrophysiologic study showed an interatrial conduction delay of 140±20ms, a normal right atrio-ventricular interval (170±30ms), and a short left atrio-ventricular interval (30±20ms).

All 7 patients exhibited 1) severely raised filling pressures, 2) features consistent with decreased left atrial (LA) compliance, and 3) IAB with a delayed LA systole. We believe that severe IAB may be responsible for a delayed LA activation that occurs against a closing mitral valve, thereby interrupting the active LV filling. Furthermore, the hindered LA emptying may induce pressure overload and increase LA stiffness.

We identified a category of HFNEF patients with a stereotyped presentation, in which IAB could be one major explanation. Whether these patients could be improved by atrial resynchronization deserves further investigation.