Choice of calcium-channels blockers after RA grafting and side effect
There is a wide range of CB; however, there are three main chemically divergent groups: dihydropyridines (eg, nifedipine, amlodipine, nicardipine, clevidipine and nicorandil), phenylalkylamines (eg, verapamil), and benzothiazepines (eg, diltiazem)26.
The choice of CB to prevent RA spasm has been empirical.
At least theoretically, all CB derivatives can be used to prevent RA graft spasm; nevertheless it has been demonstrated that dihydropyridine are the most potent vasodilator27. However, the vast majority of the studies published in literature used diltiazem as antispasmodic agent (table 1).
He and colleagues in a in-vitro study found that nifedipine was 19.5-fold more potent than verapamil and 31.6-fold more potent than diltiazem in RA precontracted with potassium; also, its efficacy on prevention of RA spasm was shown by the observation that at the usual plasma concentration, nifedipine significantly reduced RA contraction, whereas neither verapamil nor diltiazem had any effect on the RA contraction at equal concentration26.
Diltiazem may have significant negative chronotropic and inotropic effects. Its early use can increase the requirement for temporary cardiac pacing in the post-operative period.
Amlodipine is a more selective CB, thereby with less effect on the myocardium.
However, Kloner et al.28 reported that in patients with amlodipine, edema occurred in 24%, headache in 8.8% and in fatigue and dizziness in >4%.
Notably, the potential hypotensive effect of the CB may preclude the use of other secondary prevention therapies such as beta-blockers or angiotensin-converting enzyme inhibitors.
Polypharmacy is also an important concern and has been associated with increased risk of cardiac events29.