[Attempt to assess the risk of recurrence of life-threatening ventricular arrhythmia using simple non-invasive tests]

Abstract

Baroreflex sensitivity (BRS), as assessed using phenylephrine method, and depressed 24-hour heart rate variability (HRV) have been shown to be powerful predictors of life-threatening ventricular arrhythmias. However, before these tests are widely used, their methodology has to be simplified. The aim of this study was to assess the prognostic value of simple non-invasive BRS parameter (Robbe index, BRS-RI) and short-term HRV, together with left ventricular ejection fraction (LVEF) and late potentials (LP) assessment in patients after myocardial infarction (MI) with documented history of ventricular tachycardia (VT) and ventricular fibrillation (VF).

Material and methods: The observation was conducted on 53 patients after MI with documented VT or VF. They were was divided into two groups: with or without recurrence arrhythmia. During the follow-up malignant ventricular arrhythmia events occurred in 31 patients VT/VF(+), no VT or VF was recorded in the 22 subjects VT/VF(-). In all patients the following parameters were analyzed: BRS-RI (transfer function, 0.07-0.14 Hz), HRV parameters such as: SDNN, rMSSD, pNN50, LF LF (NU), LF/HF. Additionally, LVEF and LP were assessed.

Results: In the VT/VF(+) and VT/VF(-) groups, values of analyzed parameters were: BRS-RI: 4.4 +/- 2.5 and 8.4 +/- 6.1 ms/mm Hg (p=0.03); BRS-RI < or = 3 ms/mm Hg: 8/15 and 2/16 (p=0.02); SDNN: 23.0 +/- 18.0 and 20.0 +/- 11.6 ms (p=0.99); rMSSD: 70.9 +/- 69.8 and 34.1 +/- 30.2 ms (p=0.34); pNN50: 10.7 +/- 14.6 and 4.4 +/- 9.0% (p=0.7); LF: 204.5 +/- 509.7 and 160.7 +/- 265.8 ms2 (p=0.95); LF (NU): 0.5 +/- 0.4 and 0.5 +/- 0.3 (NU) (p=0.77); LF/HF: 1.3 +/- 1.2 and 2.1 +/- 2.2 (p=0.49); LVEF: 32.5 +/- 9.1 and 39.8 +/- 13.3% (p=0.03); LP: 19/24 and 15/19 (p=0.99). The only indices of prognostic values were Robbe-index and LVEF. Their prognostic value in prediction of arrhythmic event occurrence was independent of each other's and of age, time elapsed from MI and number of MI (p=0.007). Non-diagnostic values of BRS-RI were found in 22 patients (42%).

Conclusions: Among the evaluated indices, only LVEF and Robbe-index have prognostic value in prediction of life-threatening ventricular arrhythmia recurrence after myocardial infarction. However, a high percentage of non-diagnostic values obtained in BRS-RI assessment limits the usefulness of this index.