Incidence of adverse events during treatment with verapamil for suspected acute myocardial infarction

Calcium channel antagonists should be among the first-line drugs in the management of cardiovascular disease

There are a number of cardiovascular conditions in which calcium channel antagonists (CCAs) are accepted as first-line therapy, including Prinzmetal's angina and Raynaud's phenomenon. The real issue is whether symptomatic relief of angina or effective reduction of blood pressure (BP) is matched by a good safety record. In effort angina, verapamil is as safe as metoprolol, and nifedipine (tablet form) is as safe as atenolol. In unstable angina, intravenous diltiazem is better than intravenous nitroglycerin; there are no similar data on beta-blockade. Short-acting nifedipine is contraindicated in unstable angina. There is no place for CCAs in acute phase myocardial infarction and short-acting nifedipine is contraindicated. In the post-MI phase, two specific groups of patients benefit from diltiazem or verapamil: (1) those who had non-Q-wave infarcts and (2) those who are hypertensive. The DAVIT studies argue for the safety and efficacy of verapamil but do not allow comparisons with standard beta-blocker therapy. In the treatment of hypertension, the recommendation often made that a low-dose diuretic should be first-line therapy holds for the elderly with systolic hypertension but is not based on prospective studies in the case of younger patients. High-dose diuretics may have adverse effects, as reported in two case-controlled studies. Prospective outcome data favoring beta-blocker monotherapy as first-line therapy are limited, especially in the elderly, while case-control studies suggest an increased incidence of cardiac death in those treated by beta-blockers. CCAs may be the preferred first-line antihypertensive treatment for those groups in whom low-dose diuretics are unlikely to work as monotherapy.

N-acetylcysteine in combination with nitroglycerin and streptokinase for the treatment of evolving acute myocardial infarction. Safety and biochemical effects

BACKGROUND

N-acetylcysteine (NAC) has been shown to potentiate the effects of nitroglycerin (NTG) and to have antioxidant activity. This is the first study to assess the safety and effect of NAC in the treatment of evolving acute myocardial infarction (AMI).

METHODS AND RESULTS

Patients with AMI received either 15 g NAC infused over 24 hours (n = 20) or no NAC (n = 7), combined with intravenous NTG and streptokinase. Peripheral venous plasma malondialdehyde (MDA), reduced (GSH) and oxidized (GSSG) glutathione concentrations, and rate of reperfusion (using continuous ST-segment analysis) were measured. Cardiac catheterization was performed between days 2 and 5. No significant adverse events occurred. Less oxidative stress occurred in patients treated with NAC than in patients not receiving NAC (GSH to GSSG ratio 44 +/- 25 versus 19 +/- 13 at 4 hours, P < .05). NAC concentration (mean 172 +/- 79 mumol/L at 4 hours) was correlated to GSH concentration (P = .006). MDA concentrations were lower (P = .001) over the first 8 hours of treatment with NAC. There was a trend toward more rapid reperfusion (median 58 minutes, 95% confidence interval [CI] 48 to 98 minutes versus median 95 minutes, 95% CI 59 to 106 minutes; P = .17) and better preservation of left ventricular function (cardiac index 3.4 +/- 0.8 versus 2.6 +/- 0.27 L.min.m2, P = .009) with NAC treatment.

CONCLUSIONS

NAC in combination with NTG and streptokinase appeared to be safe for the treatment of evolving AMI and was associated with significantly less oxidative stress, a trend toward more rapid reperfusion, and better preservation of left ventricular function.

Streptokinase-induced transient aggravation of myocardial injury

We examined the relationship between streptokinase infusion, intensity of myocardial injury and systemic hypotension in patients receiving streptokinase for treatment of evolving acute myocardial infarction. Twenty consecutive patients treated with streptokinase for evolving acute myocardial infarction received continuous blood pressure and S-T segment monitoring of the 12 lead electrocardiogram (ECG) for at least 5 h, commencing prior to commencement of the streptokinase infusion. Aggravation of injury, manifested both by episodic increases in S-T segment elevation on the electrocardiogram (ECG) (P < 0.001), and in mean S-T segment elevation (P < 0.05) occurred within the first 20 min after initiation of streptokinase infusion. Hypotension also occurred transiently in most patients, with a mean minimum systolic blood pressure of 92 +/- 22 (S.D.) mmHg occurring 16 +/- 5 min after commencement of streptokinase. There was no correlation between the extent of aggravation of injury and that of hypotension. All patients showed ECG evidence of reperfusion, with a reduction of S-T elevation in the reference lead to 50% of maximal value, after a median of 62 min (range 9-174 min). It is concluded that streptokinase aggravates injury prior to reperfusion, although probably not via the induction of hypotension: It is possible that this effect contributes to the 'early hazard' of thrombolytic therapy.