Study of late potentials and ventricular arrhythmias in hypertensive patients with normal electrocardiograms

Losartan controlled blood pressure and reduced left ventricular hypertrophy but did not alter arrhythmias in hypertensive men with preserved systolic function

The effect of antihypertensive therapy on arrhythmias is controversial. An initial study in patients with chronic heart failure indicated that losartan, an angiotensin II receptor antagonist, may possess antiarrhythmic properties. However, the effect of AT1 receptor antagonists on arrhythmias of subjects with good systolic function has never been evaluated. Thirty-nine men with primary hypertension (18 without left ventricular hypertrophy [LVH], and 21 with LVH, aged 48.2 +/-8.6 and 50.5 +/-6.0 years, respectively), 15 healthy normotensive subjects (47.9 +/-8.5 years), and 14 highly trained athletes (34.1 +/-1.6 years) were studied. Transthoracic echocardiography and 24-hour Holter ambulatory monitoring were performed at baseline (without treatment). Hypertensive patients underwent the same examinations after 8 months of losartan administration. The prevalence and complexity of ventricular arrhythmias, and the frequency of supraventricular arrhythmias were increased in hypertensive patients with LVH compared to normotensive controls and athletes, at baseline. A similar significant reduction of blood pressure (BP) was noted in both groups of patients (p < 0.001). The LVH was reduced in hypertensives with LVH (the left ventricular mass index by 12%, the interventricular septum by 8.1%, the posterior wall by 7%, all p < 0.01). However, the arrhythmias did not change in either group of patients, even if all hypertensives were considered as 1 group. In conclusion, an 8-month course with losartan was effective in lowering BP and reducing LVH. However, the increased arrhythmias, which were registered in hypertensive patients with LVH at baseline, did not change.

Morphologic left ventricular patterns and prevalence of high-grade ventricular arrhythmias in the normotensive and hypertensive elderly

In the elderly, systemic hypertension is the main risk factor for cardiovascular diseases. Left ventricular hypertrophy, the most common adaptation to chronic pressure overload, has been recognized as an independent risk factor for an increased incidence of sudden death and arrhythmic disturbances. This study compared the prevalence of serious ventricular arrhythmias in elderly individuals with uncomplicated hypertension and in normotensive age-matched controls, using left ventricular mass index (LVMI) to differentiate patterns of anatomic adaptation to systolic, diastolic, or systolic-diastolic hypertension. The study enrolled 378 consecutive untreated elderly subjects (> or = 65 years of age), without clinical evidence of heart failure; 203 were hypertensive and 175 were normotensive. Each participant underwent standard 12-lead electrocardiography, M-mode and B-mode echocardiography, and 24-hour ambulatory electrocardiographic monitoring. Serious, statistically significant arrhythmias (Lown classes > or = 3) were present in 6.8% of normal subjects versus 17.1% of individuals with systolic, 31.5% of those with diastolic, and 20.4% of participants with systolic-diastolic hypertension. Arrhythmias did not differ in terms of left ventricular morphologic patterns or LVMI or between subgroups of hypertensive patients. Our data support the hypothesis that the pathogenesis of arrhythmias is related not to the electrophysiologic derangement of hypertrophied muscle but, rather, to the effects of hypertension on the cardiac structure. Cardiac fibrosis, one of the deleterious events accompanying hypertension, may be the main substrate for ventricular arrhythmias.

Markers of electrical instability in hypertensive patients with and without ventricular arrhythmias. Are they useful in identifying patients with different risk profiles?

BACKGROUND

Markers of electrical instability of the ventricular myocardium, namely abnormal repolarization and late potentials, are frequently observed in patients with hypertension when both ventricular arrhythmias and left ventricular hypertrophy are present. This information cannot be extrapolated to the population of hypertensive patients with ventricular arrhythmias but without left ventricular hypertrophy.

OBJECTIVE

To evaluate QT duration, QT dispersion and the incidence of ventricular late potentials in patients with essential hypertension, already on anti-hypertensive therapy, both with and without non-sustained ventricular arrhythmia.

DESIGN

The study population consisted of 49 patients with essential hypertension who were compared to 89 control normotensive subjects both with and without frequent (> 30 per h) ventricular ectopic beats (VPBs). Patients were divided into four groups: (1) hypertensive patients without VPBs (H, n = 19), (2) hypertensive patients with VPBs (HA, n = 30), (3) normotensive subjects without VPBs (C, n = 28), and (4) normotensive subjects with VPBs (CA, n=61).

METHODS

Echocardiographic parameters, QT interval, QT dispersion and signal-averaged ECG were evaluated without withdrawing anti-hypertensive drugs.

RESULTS

In no case was left ventricular hypertrophy documented. The number of VPBs during 24 h Holter recording (median 11 343 versus 7617) and the incidence of repetitive VPBs (37 versus 46% of patients) were similar in the two groups of patients (HA versus CA). Signal-averaged ECG parameters were normal and not different between the four groups. QT interval was longer in hypertensive patients compared to controls irrespective of the presence of VPBs. QT dispersion was slightly greater in subjects with VPBs, both hypertensive and normotensive, compared to subjects without arrhythmias.

CONCLUSIONS

In patients with hypertension well-controlled by drug therapy and without left ventricular hypertrophy, frequent VPBs are not associated with markers indicating an electrophysiological substrate for re-entrant arrhythmias. However, QT prolongation suggests the persistence of a higher risk of cardiovascular mortality that is independent of the presence of VPBs.

Prevalence of late potentials in adult aortic stenosis

Sudden death and syncope are well-recognized clinical manifestations of valvular aortic stenosis (AS). Furthermore, patients with left ventricular hypertrophy due to hypertension have a greater prevalence of late potentials (LP) compared with normal subjects. Chronic pressure overload in AS is frequently characterized by development of left ventricular hypertrophy. The aims of this study were (1) to determine the prevalence of LP in patients with moderate to severe AS, and (2) to investigate the relationship between LP and left ventricular hypertrophy. Signal-averaged electrocardiograms (SAECG) were recorded using a 40 Hz high pass filter in 32 patients (19 M and 13 F), aged 69 +/- 11 years with AS, and in 25 age- and sex-matched controls. QRS duration (QRSD) < 114 ms, low amplitude signal of last 40 ms (LAS40) < 38 ms and root mean square voltage of last 40 ms (RMS40) > 20 microV were considered normal. LP were considered to be present if at least two of the above criteria were abnormal. Each patient underwent a complete echo-Doppler examination and the following parameters were measured; aortic valve area, fractional shortening, left ventricular end-diastolic diameter and mass index. Coronary arteriography was performed in 17 (53%) patients. LP were present in 8 out of 32 (25%) AS patients and in 1 out of 25 controls (4%); this difference was statistically significant (P < 0.006). No difference with regard to age, sex, presence of congestive heart failure, angina, syncope, complex ventricular arrhythmias and coronary artery disease was found in AS patients with and without LP. No correlation was found between indices of left ventricular structure and function and each SAECG parameter. In conclusion, the prevalence of LP in patients with AS is higher than in controls and the presence of LP in AS might be related to factors other than coronary artery disease and left ventricular mass and/or function.

Cardiac arrhythmias and left ventricular hypertrophy in systemic hypertension and their influences on prognosis

Left ventricular hypertrophy (LVH) is the adaptative mechanism of the heart to systolic overload of the left ventricle. Nevertheless, LVH plays a role in some complications, such as cardiac arrhythmias. Patients with LVH are more likely to develop ventricular arrhythmias than the hypertensive population without LVH. Further, the relation between left ventricular mass and ventricular arrhythmias is graded and continuous. The arrhythmias described in hypertensive patients with LVH are usually isolated premature ventricular contractions. The presence of electrocardiographic criteria of LVH represents a risk of higher incidence of sudden death, especially in men. The risk is even greater in the presence of ventricular arrhythmias. The presence of late potentials has been recently characterized as more related to ventricular arrhythmias than LVH. Antihypertensive drugs that can reduce LVH also have a beneficial effect on cardiovascular morbility and mortality.