title: P-wave voltage and peaking on electrocardiogram in patients undergoing head-up tilt testing for history of syncope.
abstract: BACKGROUND
  Only scanty data are available in the literature on P-wave (PW) morphology at ECG in patients with history of vasovagal syncope undergoing diagnostic functional testing. In this study, we evaluated resting and head-up tilt testing (HUTT) related changes in PW voltage (PWV) and duration (PVD) and their relationship with triggered syncope.
  
  
  METHODS
  55 patients, mean aged 41 ± 19 y (35 F), without patent heart disease or neuropathy, underwent potentiated HUTT according to the Italian protocol. Heart rate (HR), blood pressure (BP), PR-interval, PWV and PWD were measured at rest, 15 min from passive position (15-min) and after nitroglycerine (peak-HR). PW peaking (PWP) was calculated as percent increase in PWV than baseline values. Patients were divided into 2 groups based on tilt-positive (group-A) or negative (group-B) response.
  
  
  RESULTS
  20 patients (36%) entered the group-A, whereas 35 (64%) the group-B. Higher PWV was observed at baseline in group-A (0.147 ± 0.034 mV vs 0.114 ± 0.036 mV in group-B, p=0.001), with no differences in the remaining ECG measurements. BP was lower in group-A than in B, both at 15-min and peak-HR. HUTT-related PWP in lead II (the most significant among all inferior leads) was 31 ± 30% in group-A vs 95 ± 54% in group-B (p<0.0001) at 15-min, and 52 ± 44% vs 112±72% at peak-HR, respectively (p=0.002). 75% of patients with PWP ≤ 50% experienced HUTT-triggered syncope, vs 5% of those with PWP ≥ 100% (p<0.0001).
  
  
  CONCLUSIONS
  This study shows a potential relationship between HUTT-triggered syncope and low or absent PWP, suggesting a role for atrial chamber functional involvement in the mechanisms underlying the vasovagal syncope.
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy. Electronic address: cdegregorio@unime.it.
authors.forename: Cesare
authors.initials: C
authors.lastname: de Gregorio
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy.
authors.forename: Concetta
authors.initials: C
authors.lastname: Lentini
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Grimaldi
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Zagari
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Andò
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Di Bella
authors.affiliation: Department of Clinical and Experimental Medicine, Cardiology Unit, University Hospital of Messina, Messina, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Coglitore
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D019462:Syncope, Vasovagal / Q000175:diagnosis* / Q000503:physiopathology; D018667:Tilt-Table Test
keywords: Electrocardiogram; Head-up tilt testing; P-wave peaking; P-wave voltage; Syncope; Vasovagal syncope