Electrocardiographic changes during antihypertensive treatment with diltiazem in relation to the achieved serum levels of the drug

Abstract

Lind L, Lithell H, Johansson CG, Mörlin C, Ljunghall S. Electrocardiographic changes during antihypertensive treatment with diltiazem in relation to the achieved serum levels of the drug. Scand J Clin Lab Invest 1994; 54: 337-40.

Diltiazem is a calcium channel blocker with antihypertensive and antiarrhythmic actions.

In the present study 24 hypertensive patients were treated with diltiazem (180-360 mg daily) for 6 months. The effects on the electrocardiogram (ECG) were studied and were related to the serum levels of diltiazem.

Treatment with diltiazem induced a non-significant reduction in heart rate with 3 beatsmkr¹ and decreased blood pressure (-11/-9mm Hg, p < 0.001). The treatment also induced a prolongation of the PQ-interval (+1.4cs, p < 0.02), a prolongation only being weakly related to the plasma levels of diltiazem (r = 0.28, not significant) and its metabolite MA (r = 0.37, p = 0.07). Neither was the induced increase in the QT-interval (+0.9 cs, p < 0.05), significantly related to the plasma levels of diltiazem.

In conclusion, the plasma levels of diltiazem were not clearly related to the induced changes at the ECG during antihypertensive treatment.

Key Words:

• calcium
• antagonist
• diltiazem
• electrocardiogram
• hypertension