Background: Central systolic blood pressure (cSBP) has been postulated to correlate closely with cardiovascular risk. Identifying factors associated with cSBP is therefore important. Prolonged QT interval is known to be associated with cardiovascular outcomes and might also be associated with the arterial waveform and cSBP. We investigated the possible associations between electrocardiogram wave interval and cSBP in general population samples.
Methods: Brachial blood pressure and radial arterial waveform were measured simultaneously. Augmentation index (AIx) was calculated from the radial waveform as the ratio of the height of the late systolic peak to that of the first peak. cSBP was defined as the absolute pressure of the late systolic peak.
Results: In the first panel (n = 8,085), QT interval was strongly association with AIx (r = 0.330; P < 0.001). This association remained significant even in the heart rate-adjusted analysis (r = 0.184; P < 0.001). Although subjects with a longer QT interval were older and had higher blood pressure, heart rate, and pulse wave velocity, multivariable analysis with adjustment for these covariables nevertheless identified longer corrected QT interval as an independent determinant of increased AIx and smaller pulse pressure amplification (PPa; brachial SBP minus cSBP) (β = -0.066; P < 0.001). This association was replicated in the independent second panel (n = 1,412) (β = -0.105; P < 0.001). In contrast, QRS interval was positively associated with PPa (β = 0.056; P < 0.001).
Conclusions: Longer QT interval and short QRS duration were significantly associated with arterial waveform and PPa. Our results provide a clue to the elucidation of unidentified mechanisms of the increased cardiovascular outcome and mortality risks in subjects with longer QT interval.
Keywords: QRS interval; QT interval.; blood pressure; central blood pressure; hypertension; pulse pressure amplification.