Determinants of inducibility of ventricular tachycardia

Clinical investigation: Utility of left ventricular end diastolic diameter in the prediction of susceptibility to ventricular tachyarrhythmias

BACKGROUND

Prior studies have shown the utility of using both QRS duration and QT dispersion (QTd) as predictors of risk for ventricular tachyarrhythmias (VA). Lengthening of the QRS duration represents dyssynchrony of regional myocardial wall contraction, and increased QTd similarly represents variations in myocardial repolarization. We sought to examine the left ventricular end diastolic diameter (LVEDD) as a predictor of VA susceptibility.

METHODS

Eighty-eight patients referred for electrophysiologic (EP) studies were evaluated. EP testing was performed using a standard protocol of up to three extrastimuli. QTd and QRS duration analyses were performed in a blinded manner. Values were defined as abnormal if QRS duration>120 ms, QTd>60 ms, and LVEDD>6 cm.

RESULTS

Of 88 patients (65 males; 23 females; mean age 67+/-15 years), 33 were inducible by EP testing. Patients with either increased QRS duration or QTd are shown to be at greater risk for VA inducibility. LVEDD is a strong predictor of inducibility for VA (p<0.02 between inducible and non-inducible patients). LVEDD in combination with QRS duration and QTd, further strengthens predictability for VA (p<0.03 for QRS duration and p<0.02 for QTd) with a trend towards inducibility as each value increases. Combination of the three parameters of QRS duration, QTd, and LVEDD was 91% sensitive for the identification of those patients inducible for VA.

CONCLUSION

The LVEDD is an echocardiographic value that strongly predicts VA inducibility, and when combined with QRS duration and QTd, identifies patients at higher risk for these tachyarrhythmias.

Echocardiographic predictors of survival in patients undergoing radiofrequency ablation of postinfarct clinical ventricular tachycardia

INTRODUCTION

The aim of this study was to determine the predictive value of echocardiographic parameters of systolic left ventricular (LV) dysfunction for survival in a group of patients with "mappable" ventricular tachycardia (VT) after myocardial infarction who underwent radiofrequency ablation (RFA) of their clinical VT(s).

METHODS AND RESULTS

RFA of at least one inducible, "mappable," and clinical VT was attempted in 61 patients. In total, 63 (79%) of 80 target clinical VTs were ablated successfully, such that clinical VT(s) were noninducible in 49 (80%) of 61 patients. At the last recorded follow-up (range 2 to 98 months; mean 21 +/- 20), nonfatal VT recurrences were observed in 11 (22%) patients; 10 (16%) patients died. On univariate analysis, a higher LV end-diastolic volume (LVEDV; P = 0.008) and, by multivariate analysis, applying backward selection of variables, older age (P = 0.03) with a higher LVEDV (P = 0.003) predicted patients more likely to die. When age and LV ejection fraction (LVEF) were excluded, LV end-systolic diameter (LVESD; P = 0.007) was the most significant predictor of survival.

CONCLUSION

In our patient population with postinfarct VT who underwent RFA of mappable clinical VT(s), LVEF did not predict survival. In this group of patients with overall low mean LVEF (<35%), older age together with higher LVEDV and LVESD predicted patients who were more prone to die. LV size rather than LVEF correlated with survival.