Aten D contains atenolol and chlorthalidone. Atenex contains atenolol.
Atenolol may interfere with lipid metabolism and hence can have adverse effects on cholesterol. Normally the effect is on Very Low Density Lipoprotein (VLDL) which increases and High Density Lipoprotein which decreases. The overall effect is increase in cholesterol.
In patients below 55 years of age, the first line therapy should be losartan (sold as Losacar) 50mg once daily. Since your wife is already taking atenolol + chlorthalidone (a diuretic), the alternative would be Losacar-H one tablet daily. Losacar-H contains losartan + hydrochlorthiazide (a diuretic quite similar to chlorthalidone). If the BP is not controlled, then in the evening plain Losacar can be added.