The effect of morphine on blood pressure and cardiac output in patients with acute myocardial infarction

Morphine in acute coronary syndrome: systematic review and meta-analysis

OBJECTIVE

Morphine is frequently used in acute coronary syndrome (ACS) due to its analgesic effect, it being recommended in the main cardiology guidelines in Europe and the USA. However, controversy exists regarding its routine use due to potential safety concerns. We conducted a systematic review of randomised-controlled trials (RCTs) and observational studies to synthesise the available evidence.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

CENTRAL, MEDLINE, EMBASE and trial registries.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included RCTs and observational studies evaluating the impact of morphine in cardiovascular outcomes or platelet reactivity measures.

DATA EXTRACTION AND SYNTHESIS

Data were screened, extracted and appraised by two independent reviewers. The data were pooled results using a random-effects model. Outcomes included in-hospital mortality, major adverse cardiovascular events (MACE), platelet reactivity (using VerifyNow) and bleeding, reported as relative risk (RR) with 95% CI. We assessed the confidence in the evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. We followed the Meta-analysis Of Observational Studies in Epidemiology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Five RCTs and 12 observational studies were included, enrolling 69 993 participants. Pooled results showed an increased risk of in-hospital mortality (RR 1.45 [95% CI 1.10 to 1.91], low GRADE confidence), MACE (RR 1.21, 95% CI 1.02 to 1.45) and an increased platelet reactivity at 1 and 2 hours (59.37 platelet reactivity units [PRU], 95% CI 36.04 to 82.71; 68.28 PRU, 95% CI 37.01 to 99.55, high GRADE confidence) associated with morphine. We found no significant difference in the risk of bleeding. We found no differences in subgroup analyses based on study design and ACS subtype.

CONCLUSIONS

Morphine was associated with an increased risk of in-hospital mortality and MACE but the high risk of bias leads to low result confidence. There is high confidence that morphine decreases the antiplatelet effect of P2Y12 inhibitors.

PROSPERO REGISTRATION NUMBER

CRD42016036357.

Analgesic treatment in acute myocardial infarction. A double-blind comparison of ketobemidone + the spasmolytic A29 (Ketogan) and morphine

The analgesic effect of ketobemidone hydrochloride + the spasmolytic component A29 (Ketogan) and morphine hydrochloride was compared double-blindly in patients with suspect acute myocardial infarction. The test drugs were administered i.v. in an initial dose of 0.5 ml (2.5 mg Ketogan, 5 mg morphine) followed, if necessary, by additional injections of 0.25 ml. Altogether, 309 patients participated in the trial. The total consumption of the test drugs showed that 5 mg Ketogan was equipotent with 10 mg of morphine. Treatment with Ketogan resulted in a significantly higher proportion of patients who were completely free of pain 15 and 30 min after the initial injection: 16% and 15% more, respectively, compared to morphine. Within 2 hours after the initial injection, approximately 15% of the patients in both treatment groups had reported nausea and about 7% had vomited (patients who vomited or were nauseated before treatment were not included in this analysis). The frequency of other side-effects was low, with no differences between the two treatment groups. Morphine caused a greater reduction of the systolic blood pressure than Ketogan. The effect of both drugs on pulse rate and respiration was the same.

Double-blind study of the effect of cardioselective beta-blockade on chest pain in acute myocardial infarction

A double-blind study including three different cardioselective beta-blockers, practolol, H 87/07 and metoprolol, was performed in 54 patients with acute myocardial infarction and chest pain shortly after onset of symptoms. Transmural infarctions were found in 42 patients while 12 patients had nontransmural infarctions. Chest pain and the product of heart rate and systolic blood pressure were significantly reduced in the beta-blocker groups whereas no changes were seen after saline. All patients with nontransmural infarctions and 14 out of 29 with transmural infarctions got pain relief lasting for at least 30 min. None of the patients developed signs of left ventricular backward failure, shock, or bradycardia. A decrease in ST segment elevation was observed in all the transmural infarctions after beta-blockade. No changes in ST segment elevation were found after analgesics when given after saline, but in some cases an increase was seen in this parameter when analgesics were given due to insufficient pain relief after beta-blockers or due to return of chest pain. It is suggested that pain relief by beta-blockers indicates decrease of myocardial ischemia.

Association of intravenous morphine use and outcomes in acute coronary syndromes: results from the CRUSADE Quality Improvement Initiative

BACKGROUND

Although intravenous morphine is commonly used for the treatment of chest pain in patients presenting with non-ST-segment elevation acute coronary syndromes (NSTE ACS), its safety has not been evaluated. The CRUSADE Initiative is a nonrandomized, retrospective, observational registry enrolling patients with NSTE ACS to evaluate acute medications and interventions, inhospital outcomes, and discharge treatments.

METHODS

The study population comprised patients presenting with NSTE ACS at 443 hospitals across the United States from January 2001 through June 2003 (n = 57,039). Outcomes were evaluated in patients receiving morphine versus not and between patients treated with morphine versus intravenous nitroglycerin.

RESULTS

A total of 17,003 patients (29.8%) received morphine within 24 hours of presentation. Patients treated with any morphine had a higher adjusted risk of death (odds ratio [OR] 1.48, 95% CI 1.33-1.64) than patients not treated with morphine. Relative to those receiving nitroglycerin, patients treated with morphine also had a higher adjusted likelihood of death (OR 1.50, 95% CI 1.26-1.78). Utilizing a propensity score matching method, the use of morphine was associated with increased inhospital mortality (OR 1.41, 95% CI 1.26-1.57). The increased risk of death in patients receiving morphine persisted across all measured subgroups.

CONCLUSIONS

Use of morphine either alone or in combination with nitroglycerin for patients presenting with NSTE ACS was associated with higher mortality even after risk adjustment and matching on propensity score for treatment. This analysis raises concerns regarding the safety of using morphine in patients with NSTE ACS and emphasizes the need for a randomized trial.

Adverse effects due to morphine sulfate. Challenge to previous clinical doctrine

Despite a lack of clinical data in this area, conventional wisdom holds that morphine sulfate induces vagally mediated conduction defects, especially in patients with inferior myocardial infarction. To assess the accuracy of this "clinical pearl," the records of 244 patients admitted to the Barnes Hospital Cardiac Care Unit with suspected acute myocardial infarction were reviewed to determine the frequency of deleterious cardiovascular effects related to the administration of morphine sulfate. Of 184 patients (156 subsequently documented to have infarction) who received morphine sulfate, four patients had symptomatic hypotension temporally associated with morphine sulfate administration. This represented a frequency of 2.2 percent for all patients treated with morphine sulfate and a frequency of 2.6 percent in those with proved infarction. In each instance, the heart rate response was inappropriate, i.e., decreased or less markedly accelerated than might be expected given the reduced blood pressure, suggesting a vagal mechanism for the adverse effects. Only one of the four patients had inferior infarction, and in three of four instances, the adverse effect occurred after the first dose. All patients subsequently received morphine sulfate without evidence of toxicity. No case of narcotic-induced conduction abnormality was identified. This series, which is the most extensive evaluation of the topic, documents that adverse cardiovascular effects due to morphine sulfate are rare and do not conform to preconceived clinical doctrine. They consist of inappropriate heart rate responses to hypotension rather than conduction defects and are not particularly associated with inferior myocardial infarction.

Ischemic pain relief in patients with acute myocardial infarction by intravenous atenolol

Pain relief in acute myocardial infarction (AMI) by the beta-adrenoceptor antagonist, atenolol, was demonstrated by three separate studies. First, 18 patients were randomized to double-blind intravenous atenolol (5 mg) or saline immediately after admission, followed by oral atenolol (50 mg) or placebo 10 minutes later. In patients receiving atenolol, pain relief coincided with reduction in heart rate (HR), systolic blood pressure (SBP), and HR X SBP product (p less than 0.05); however, pain and these parameters were unchanged by placebo. The degree of pain relief was related to the reduction in cardiac work achieved (r = 0.725; p less than 0.001). A second open study involving 22 patients receiving intravenous atenolol (5 to 15 mg) early after AMI showed ischemic pain relief in 17 patients. They achieved a more significant reduction in HR X SBP product than those whose pain remained unchanged (p = 0.004). Finally, a retrospective study of 163 patients randomized to either atenolol or no beta blockade early after AMI revealed that patients receiving atenolol needed less opiate analgesia after admission (p less than 0.001). The safety of this therapy was illustrated by a decreased incidence of left heart failure and atrial fibrillation and no tendency to second- and third-degree heart block.

Effects of morphine on left ventricular dimensions and function in patients with previous myocardial infarction

To assess the effects of morphine sulfate on left ventricular function and dimensions we administered 15 mg of this agent to 11 stable patients with previous transmural myocardial infarction. All studies were carried out in the supine position. Before morphine administration an echocardiogram was obtained, and this procedure was repeated at 15, 30, 60, 120, and 240 min after morphine. Heart rate decreased from a control value of 69 +/- 4 to 62 +/- 5 beats/min 2 h after morphine (p less than 0.01, analysis of variance); this slower heart rate persisted for 4 h after morphine. Serial measurements of blood pressure, echocardiographic ejection fraction, percent of fractional shortening, and mean normalized velocity of circumferential fiber shortening also showed no significant alterations after morphine. We conclude that in stable patients with chronic ischemic heart disease studied in the supine position, 1) morphine exerts no effect on left ventricular dimensions, an observation which does not support the concept that this agent acts in humans by producing a 'pharmacologic phlebotomy'; and 2) morphine does not alter left ventricular function at rest. Whether different results will be found in patients with increased sympathetic activity, such as occurs in the setting of an acute myocardial infarction or during an episode of acute pulmonary edema, remains to be investigated.

Comparative effects of morphine, meperidine and pentazocine on cardiocirculatory dynamics in patients with acute myocardial infarction

The cardiocirculatory effects of the commonly used parenteral analgesics, morphine sulfate 15 mg, meperidine hydrochloride 100 mg and pentazocine 60 mg, each administered intravenously, were compared in 12 patients with acute myocardial infarction during cardiac catheterization and by echocardiogram. No untoward hemodynamic effects occurred following the administration of morphine or meperidine. In contrast, pentazocine produced significant (p less than 0.01 to less than 0.05) increases in systemic and pulmonary arterial pressures, left ventricular filling pressure, systemic vascular resistance, and systolic and diastolic dimensions; and decreases in left ventricular ejection fraction and mean velocity of circumferential fiber shortening. These deleterious actions of pentazocine appeared due to peripheral vasoconstriction and negative inotropic properties. Further, pentazocine-induced increases in left ventricular preload and afterload increased myocardial oxygen demands. Since this study demonstrates that pentazocine is hazardous in myocardial infarction, morphine and meperidine are the preferred analgesics in this condition.