Ventricular Activation Time as a Marker for Diastolic Dysfunction

Abstract

Hypertension in the developed world affects up to 30% of adults causing a significant disease burden. Poorly controlled hypertension precipitates structural changes resulting in heart failure. Reports suggest that diastolic left ventricular dysfunction may be the earliest detectable sequence that may precede left ventricular hypertrophy clinically detected by the standard 12-lead electrocardiogram voltage criteria. Early diagnosis of hypertension, focusing on diastolic dysfunction parameters by electrocardiogram, is of clinical value, but not clinically well established yet. Only few studies have investigated atrial changes, reflected by P wave voltage/duration abnormalities, in diastolic dysfunction patients. These were criticized by the low sensitivity to disease severity and pathophysiology identification. Hence, the need for new electrical markers was urged. As early as 1982, the close relationship between the delays in the time for ventricular depolarization "called ventricular activation time" (known also as intrinsicoid deflection) and left atrial (LA) abnormalities was documented in spontaneous hypertensive rat models. However, we know little about similar changes in humans. Ventricular activation time, measured in milliseconds on the surface electrocardiogram from the onset of the QRS complex to the peak of the R wave (QR interval), has provided a new marker in predicting diastolic dysfunction. The ventricular activation time prolongation in diastolic dysfunction patients, without left ventricular hypertrophy, has proven association and is proportionally increased with diastolic dysfunction progression (from grade I to grade III). Other studies have examined the direct relationship between diastolic dysfunction and atrial changes presented by relatively novel electrocardiogram P wave markers (P wave terminal force in lead V1 and P wave dispersions). We therefore reviewed the available evidence of novel interval electrocardiogram markers in newly diagnosed hypertensive patients with evidence for diastolic dysfunction.