Electrophysiological and therapeutic implications of cardiac arrhythmias in hypertension

Hypertension, especially if associated with left ventricular hypertrophy (LVH), is a risk factor in complex ventricular arrhythmia (VA) and sudden cardiac death (SCD). To determine the effectiveness of the clinical use of programmed ventricular stimulation (PVS) we studied 40 symptomatic hypertensive patients after excluding coronary heart disease (CHD), as characterized by dizziness and palpitation, syncope, aborted SCD and/or documented complex VA. PVS revealed a normal result, i.e. a maximum of six ventricular echobeats, in 70% (group A) and a pathological result, i.e. ventricular tachycardia (VT) or fibrillation (VF) in 30% (group B). Both groups differed significantly with respect to LV (left ventricular) muscle mass: 158±45 (A) vs. 222±112 (B)g. m−2, LVEF (left ventricular ejection fraction): 71±17% (A) vs. 47±18% (B) and LV end-systolic volume index: 34±25 (A) vs. 63±27 (B) ml. m−2. Coronary reserve was comparably reduced in both groups: 2·6±1·0 (A) vs. 2·3±0·6 (B). In 3/8 (37%) patients with aborted SCD and VT/VF the clinical VA (2/2 VT and 1/6 VF) could be induced, whereas in the remaining five patients nsVT or no complex VA was induced. The therapeutic regimen included no drugs in 30%, β-blockers in 50%, serial drug testing in 12% and implantation of an automatic cardioverter defibrillator (AICD) in 8% of patients. Ventricular late potentials (LPs), detected by the signal averaging electrocardiogram, represent zones of delayed myocardial activation, which may become an origin of ventricular tachycardias. Three criteria constitute a positive LP: (1) QRS duration>114 ms, (2) root mean square voltage of the last 40 ms 38 ms. To look for the prognostic value of LP in hypertension we investigated 43 hypertensive patients without evidence of CHD. All three criteria were positive in 4/43 patients (9%), three of them demonstrating inducible monomorphic VT during PVS. 17/30 patients (56%) with LVH had at least one positive criterion, whereas only one out of 13 patients without left ventricular hypertrophy (8%) had one positive criterion. Symptomatic patients presenting with syncope, aborted SCD or documented VT/VF differed significantly from patients without symptoms or complex arrhythmias in regard to all three criteria. Conclusion In hypertensive heart disease clinical arrhythmias as well as the result of electrophysiological testing are closely related to left ventricular performance and hypertrophy. PVS is appropriate to detect reentrant VT, whereas for induction of primary VF, trigger mechanisms other than PVS are necessary. Nevertheless, PVS is an aid to deciding whether to use conservative drug or invasive AICD therapy in high risk patients. Late potentials have a significantly higher prevalence in hypertensive patients with LVH compared to those without LVH. LP analysis aids identification of patients prone to VT and may therefore be used to screen symptomatic hypertensive patients.